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Atkins, P. (2000). The elements of physical chemistry. 3. ed. Oxford: Oxford University

Press. ISBN 9780198792901.

Bakker, H. J. (2008). Structural dynamics of aqueous salt solutions. Chemical Reviews

108(4), 1456-1473.

Huheey, J. (1993). Inorganic chemistry : principles of structure and reactivity. 4. ed. New

York NY: HarperCollins College Publishers. ISBN 9780060429959.

Kristiansson, O. & Lindgren, J. (1991). Infrared spectroscopic studies of concentrated

aqueous electrolyte solutions. The Journal of Physical Chemistry 95(3), 1488-1493.

Marcus, Y. (2009). Effect of Ions on the Structure of Water: Structure Making and

Breaking. Chemical Reviews 109(3), 1346-1370.

Nič, M., Jirát, J., Košata, B., Jenkins, A. & McNaught, A. (Eds.) (2009a). coordination

entity. IUPAC Compendium of Chemical Terminology. 2.1.0. ed. Research Triagle Park,

NC: IUPAC. ISBN 0-9678550-9-8.

Nič, M., Jirát, J., Košata, B., Jenkins, A. & McNaught, A. (Eds.) (2009b). coordination

number. IUPAC Compendium of Chemical Terminology. 2.1.0. ed. Research Triagle Park,

NC: IUPAC. ISBN 0-9678550-9-8.

Persson, I. (1984). X-ray scattering on liquids, solutions,melts and nonchrystaline solids.

Rode, B. M. & Hofer, T. S. (2006). How to access structure and dynamics of solutions: The

capabilities of computational methods (Special Topic Article). Pure and Applied Chemistry

78(3), 525-539.

Rode, B., Hofer, T., Randolf, B., Schwenk, C., Xenides, D. & Vchirawongkwin, V. (2006).

Ab initio quantum mechanical charge field (QMCF) molecular dynamics: a QM/MM – MD

procedure for accurate simulations of ions and complexes. Theoretical Chemistry Accounts:

Theory, Computation, and Modeling (Theoretica Chimica Acta) 115(2), 77-85.

Ι

1

On the Structure and Dynamics of the Hydrated Sulfite Ion in Aqueous Solution

– An ab initio QMCF MD Simulation and Large Angle X-ray Scattering Study

Lars Eklund,a Tomas S. Hofer,b Andreas Pribill,b Bernd M. Rode b and Ingmar Persson a,*

a Department of Chemistry, Swedish University of Agricultural Sciences, P.O.Box 7015, SE-750 07

Uppsala, Sweden.

b Theoretical Chemistry Division, Institute of General, Inorganic and Theoretical Chemistry,

University of Innsbruck, Innrain 52a, A-6020 Innsbruck, Austria,

Graphical Abstract

Synopsis

The sulfite ion has an asymmetric hydration sphere with three water molecules hydrogen bound to each of the sulfite oxygen, and with 3-4 water molecules clustered outside the lone electron-pair. An angular radial distribution analysis has shown that the water exchange only takes place between the water molecules clustered outside the lone electron-pair and the aqueous bulk. This is opposite to the hydrated sulfate ion where the three water molecules, symmetrically hydrogen bound to each sulfate oxygen, exchange directly with the aqueous bulk.

2

Abstract

Theoretical ab initio quantum mechanical charge field molecular dynamics (QMCF MD) formalism

has been applied in conjunction with experimental large angle X-ray scattering to study the

structure and dynamics of the hydrated sulfite ion in aqueous solution. The results show that there

is a considerable effect of the lone electron-pair on sulfur concerning structure and dynamics in

comparison with the sulfate ion with higher oxidation number and symmetry of the hydration shell.

The S-O bond distance in the hydrated sulfite ion has been determined to 1.53(1) Å by both

methods. The hydrogen bonds between the three water molecules bound to each sulfite oxygen are

only slightly stronger than in bulk water, and the sulfite ion can therefore be regarded as a weak

structure maker. The water exchange rate is somewhat slower for the sulfite ion than for the sulfate

ion, �0.5 = 3.2 and 2.6 ps, respectively. An even more striking observation in the angular radial

distribution (ARD) functions is that the for sulfite ion the water exchange takes place in close

vicinity of the lone electron-pair directed at its sides, while in principle no water exchange did take

place of the water molecules hydrogen bound to sulfite oxygens during the simulation time. On the

other hand, for the hydrated sulfate ion in aqueous solution one can clearly see from the ARD that

the distribution of exchange events is symmetrical around the entire hydration sphere.

3

Introduction

The hydration of anions is essential due to its immense importance in chemical and biological

reactions. When a reaction takes place in an aqueous solution the reaction is influenced by the

exchange between the reactants and the solvent molecules. The effects of hydration is however not

limited to the local effect of interactions with the hydrated ion itself but also with the macroscopic

properties of the solution. Studies of partially reduced hydrated anions such as sulfite have been

scarce, especially the effects comparing anions with different hydration symmetry.

Sulfite plays a major role in the production of many chemicals among the most important is the

production of sulfuric acid. There is a large number of registered patents involving the sulfite ion in

aqueous systems.1 Clearly, knowledge of the structure and dynamics of the hydrated sulfite ion in

aqueous solution is vital in many aspects, but poorly studied so far. The use of theoretical

simulations in combination with experimental structure determination is particularly powerful as it

gives complementary information from different starting points at different timescales. The time

average structure found with the X-ray scattering can verify the theoretical model with the lowest

energy state in the simulation and the simulation gives information about short time events at the

sub femto-second level unattainable by present experimental methods. This information is

especially valuable in systems with weak interactions since these are particularly affected by high

exchange rates.

The aim of the present study is to determine the structure and dynamics of the hydrated sulfite

ion in aqueous solution by both experimental and theoretical methods. The sulfite ion has a lone

electron-pair on the central sulfur atom which is expected to influence both structure and the

dynamics in comparison to the symmetric sulfate ion.2 The sulfite oxygens have three free electron-

pairs, which is of importance for the hydrogen bonding acceptor properties. The structure of the

hydrated sulfite ion in aqueous solution will be discussed in terms of how strong the hydrogen

bonds of the hydrating water molecules are in comparison with the strength of hydrogen bonds in

the aqueous bulk. Thus, what is the structural relationship of the thermodynamically determined

properties in regard to the structure making or breaking properties3,4 .Comparisons are made with

the.sulfate ion to study the effects of decreasing the symmetry of the hydration shell of hydrated

4

oxosulfur anions.

Experimental

Chemicals. Sodium sulfite, Na2SO3 (pro analysis, Merck), and sodium hydroxide, NaOH (reagent

grade, Sigma-Aldrich), were used without further purification.

Solution. The solution for the LAXS experiment was prepared by dissolving a weighed amount of

sodium sulfite in deionized Milli Q filtered water, and pH was adjusted to 12.0 by addition of a

small amount of sodium hydroxide to a final concentration of 1.5987 mol∙dm-3, and a density of

1190.4 g/L. The water concentration in this solution was 54.892 mol∙dm-3.

LAXS. The scattering of MoKα X-ray radiation, λ=0.7107 Å, from the free surface of the aqueous

sodium sulfite solution was measured in a large angle Θ-Θ goinometer described elsewhere.5 The

solution was contained in a teflon cup filled until a positive meniscus was observed generating a flat

surface in the irradiated region. The container was placed inside an air-tight radiation shield with

beryllium windows. The scattered radiation was monchromatised using a LiF(200) single crystal

focusing monochromator. The scattering was determined at 446 angles in the angle range of 0.5 < Θ

< 65º, where the scattering angle is 2Θ. At each angle 100,000 X-ray quanta where counted, and the

entire angle range was scanned twice corresponding to a statistical error of about 0.3 %. The

divergence of the x-rays was defined through combination of divergence-collecting-focal slits of

¼o-½o-0.2 mm and 1o-2o-0.2 mm. Three different Θ-regions where scanned to get a suitable

counting rate and change in angle, with overlapping regions to enable scaling of the data. The data

collection and treatment are described in detail elsewhere.5 All data treatment was carried out using

the KURVLR program,6 and the structural parameters in the theoretical model where refined by

minimizing U = w(s)Σs2[iexp(s)-icalc(s)]² using the STEPLR program.7,8 The experimental data were

normalized to a stoichiometric unit containing one sulfur atom, using the scattering factors f for

neutral atoms, including corrections for anomalous dispersion, Δf' and Δf'',9 Compton scattering10,11

and multiple scattering events. The latter is especially important as it plays a significant role since

the molar absorption coefficient of the solution was low, μ = 2.113 cm-1.

5

QM/MD through QMCF. In this study the simulation was divided into two steps. In the initial

step the system was equilibrated for 6.5 ps, where the system momentum, energy and temperature

were closely monitored, and the molecular geometry was analyzed each 0.8 ps. After this initial

equilibrium simulation a data sampling was started which lasted for 14 ps. A step size of 0.2 fs was

used in both the equilibrium and sampling phase. The flexible BJH-CF2 water model12 was used

enabling the study of explicit hydrogen motion of the water molecule. The simulation of the

hydrated sulfite ion in aqueous solution used ab initio quantum mechanical charge field molecular

dynamics (QMCF).13 The QMCF approach employs the Hartree-Fock (HF) level to evaluate the

intermolecular forces in the quantum mechanical region containing the solute molecule and two

layers of hydration. In the past the HF approach was successfully employed in QMCF MD

simulation studies of hydrated sulphate.3 During the computation of the interaction between

particles in the QM and MM regions, the QM region is further separated into an inner core and

outer layer region. Particles located in the layer zone interact with the MM atoms via a Coulombic

and a non-Coulombic term. Due to the large distance between particles in the core region and the

QM/MM interface, atoms in the core region interact with particles in the MM region only via a

Coulombic potential as the non-Coulombic contribution is negligible14. This is of particular

advantage in the case of complex solute species such as the sulfite ion. The QM core radius was set

to 4.5 Å, the total QM radius was 7.2 Å. The QM region contained roughly 45 water molecules

throughout the simulation. The simulation box used was the same as reported elsewhere.15 The

phosphate anion was replaced by sulfite which had been structure optimized together with 10 water

molecules using Gaussian.16 A periodic boundary box with the edge length of 31.4 Å was used

containing 1000 water molecules, with a density of 0.997 g∙cm-3 at the target temperature 298 K,

and thermostated via the Berendsen weak coupling algorithm.17 The reaction field approach was

employed to account for the error associated to the application of a Coulombic cutoff set to 12.0 Å.

The simulation was carried out using the DZP -dunning basis sets18,19 and TURBOMOLE 6.00.20

Analysis methods of the QMCF simulation. Radial distribution functions (RDFs) with different

6

kind of atoms as origin were used for the radial population analyses. This can be expressed as

g(r) = V/N2 <n(r,Δr)>M /4�r2Δr. The main difference between an experimental RDF expressed as

D(r)-4�r2ρo from scattering experiment and the RDF generated from a simulation is that in the first

case the center of increased electron density in space is regarded as atoms and the distance between

such centra as an atom-atom distance as determined in the experiment, while in the simulations the

position of the atom centres is known and the distribution of the atoms is calculated.

By constraining the analysis of the RDF within overlapping conical regions with a central

vector defined as the sum of the three sulfur bound oxygens, the distribution around the ion can be

probed as a function of distance and angle, a so called angular radial distribution (ARD) function

which is dependent of the distance from a given center D(r,α). In this analysis of the simulation α

was 22.5°. By giving a radial criteria a population analysis inside a given band can be made, or

sphere of affected waters. If this is done over the entire simulation time the coordination number

distribution over time can be calculated. The mean residence time, MRT, τi, was calculated in a

radial sphere of 2 to 5 Å from the central sulfur atom. The MRT is the time a given atom spends

inside a given region over the entire simulation. The exchange rate analysis which counts the

number of crossings of the region border is related to this analysis. By counting the number of

exchange events with a residence time of at least 0.0 and 0.5 ps defines the sustainability of

exchange Sex=N0.5ex/N0

ex and is related to the strength of the interactions between the ligand and

central ion. The higher Sex value the lower the probability of exchange given the same ligand

availability. This means stronger interactions with the ligands in that coordination shell. Density

plots were created by population analysis in a rotating periodic box centered on the sulfur within the

simulation box. In order to analyse the angular distributions of Ow···S·· ·Ow the system was

hemispherically partitioned with a plane perpendicular to the dipole moment of the sulfite ion and

passing through the sulfur atom, Figure 1. The angular distribution functions could then be

separated based on in which hemisphere the oxygen resides. Further studies on the sulfur oxygen,

OSO3, water oxygen, Ow, was done through analysis of the tilt of the OSO3···Ow vector, here denoted

7

OO, with respect to the plane of the water molecule. The angle between the dipole vector of the

water molecules and OO was also analysed. For both the tilt and the dipole calculations a sphere of

3 Å around the OSO3 was probed. The tilt shows the out- of- plane angle of the OO irrespectively of

the in-plane orientation of the water, and the dipole angle takes in consideration the in plane

movement of the waters dipole orientation. These two analysis methods thereby describe the

orientations of waters in the hydration shell as relevant for hydrogen bonding to the OSO3.

Results and Discussion

Large Angle X-ray scattering

The experimental radial distribution function RDF for the aqueous sulfite solution shows four

peaks at 1.5, 3.0, 3.7 and 4.2 Å, Figure 2. The peak at 1.5 Å corresponds to the mean S-O bond

distance in the sulfite ion, and has been refined to 1.53(1) Å. This S-O bond distance is slightly

longer than in the solid structures of sulfite salts only electrostatically interacting with monovalent

counter ions, mean 1.513 Å, but it is identical to the S-O bond distances observed in salts there the

metal ion has a complete hydration shell allowing hydrogen bonding to the sulfite ion, mean 1.534,

Table S1. Furthermore, in the latter salts each sulfite oxygen atom accepts hydrogen bonds to three

neighboring water molecules. This shows that the hydrogen bonding to the sulfite oxygens increases

the mean S-O bond length with 0.015-0.02 Å as it has been found in similar systems.3 The main

peak at 3.0 Å corresponds to the Ow···Ow distances in aqueous bulk, Ow·· ·Ow, and between sulfite

oxygens and hydrating water molecules, OSO3···Ow. It has not been possible to separate these

distances due to their similar values, and the mean value of these distances has been refined to

2.878(4) Å. This is just slightly shorter than the mean Ow···Ow distance in aqueous solutions, 2.89

Å.3,21 This strongly indicates that the OSO3···Ow distances are slightly shorter and the hydrogen

bonding slightly stronger than in the aqueous bulk. The weak peaks at 3.7 and 4.2 Å are assigned to

S···Ow distances to the water oxygens hydrogen binding to sulfite and the water molecules outside

the lone electron-pair, respectively. These have been refined to 3.68(3) and 4.16(4) Å, respectively.

The S···Ow distance corresponds to a tetrahedral S-OSO3···Ow angle strongly supporting that three

8

water molecules hydrogen bind to each sulfite oxygen, as also found in the solid state, see above,

and in the QMCF simulation, see details in next section. The longer S···Ow distance to the water

molecules is assumed to be located outside the lone electron-pair shows that the hydration shell

around the sulfite ion is irregular and that the lone electron-pair takes up significant space. The

structure of the hydrated sodium ion is in good agreement with previous studies.3 The structure

parameters of the aqueous sodium sulfite solution studied are summarized in Table 1.

QMCF Simulations

Radial distribution functions, RDFs, of individual atom-atom distances were calculated from

the final result of the QMCF/MD simulation, Figures 3a-e, the distances determined in the hydrated

sulfite ion in the simulation are compared with those from the LAXS data in Table 1. Each sulfite

oxygen bind three water molecules through hydrogen bonding. The peaks at 3.73 and 4.11 Å with

FWHM values of 0.530 and 0.370 Å, respectively, correspond to the mean S···OSO3p and S···OSO3d

distances, Figure 3d1; SO3p and SO3d refer to water molecules interacting with sulfite oxygens and

the water molecules outside the lone electron-pair, respectively. However, these distances are

influenced by long-range S···H and O···H interactions and the given values are therefore somewhat

uncertain. By studying the RDF of the S·· ·H distances in detail, Figures 3b and 3b1, the S···HSO3p1

is determined to 2.79 Å and S···HSO3d 2.99 Å. There is a third distance in the detailed

distinguishable in the S·· ·H plot at 4.2 Å which corresponds to HSO3p2. HSO3p1 and HSO3p2 represent

hydrogens closer to the sulfur than the water oxygen to which it is bound (SO3p1) and further away

(SO3p2). HSO3d is hydrogen bound to water molecules in the vicinity of the sulfur lone pair.

Contrary to the experimental LAXS data the RDF from simulation is built up by separable pair

functions and can therefore be resolved, for the OSO3···Ow and Ow···Ow, with the distances at 2.77

Å and 2.83 Å respectively, Figure 3e, in dilute solution. The contribution of the hydration sphere

to the total interactions is small, in this simulation about 300 times less that the bulk contribution.

The contribution increases with concentration of the solute of course and at the concentrations used

in the LAXS measurement it becomes quite significant. The difference between oxygen oxygen

distances for bulkwater (Ow···Ow) and the waters of the first hydration shell (OSO3···Ow ) is 0.06 Å

9

wich is consistent with the geometries of the LAXS measurments. The S-O bond distance obtained

from the QMCF simulation, Figure 3b, is in full agreement with the experimental LAXS study, as

well as the distances to the proximal and distal waters Tables 1 and 2. The S···H and Osulfite· · ·H

distances, Figures 3c and 3d, shows shorter distances than the S-O and Osulfite· · ·Oaq distances,

Figure 3e, which show that the orientation of the hydrogens is towards the anion.

The distribution of coordination number (CN) is shown in Figure 4 giving an average of 12.5

showing the presence of only one coordination sphere of water molecules different from those in

the bulk, which is in full agreement with the observations made by LAXS, see above.

An ARD function was constructed in order to study the structure and dynamics of the

hydrated sulfite in more detail, Figure 5. Figure 6,left panel, shows that there are areas outside of

the hydration sphere that show zero occupation of oxygen throughout the duration of the simulation

time except for a small area diametrically to the lone pair. This means that apart from a small

exchange diametrically across from the sulfur lone-pair no exchange between the bulk water

molecules and the water molecules hydrogen bound to the sulfite oxygen takes place. In principle

all water exchange is directed through a cone of water molecules outside the lone electron pair. This

means that a water exchange event of the water hydrogen bound to sulfite oxygen requires that it

must be transferred from a point in the hydration sphere and across the spherical boundary. If

D(r,α)sulfur-oxygen = 0 for a given r,α on the spherical boundary, no trajectory may have passed

through that coordinate and no exchange have taken place along that trajectory. The ARD of the

hydrated sulfate ion, SO42- (aq), Figure 6 right panel, in aqueous solution clearly show that sulfate

has a symmetric hydration sphere with water exchange taking place uniformly over the entire

sphere. If we compare this with the sulfite ion which has an asymmetrical behavior as discussed

above, we can conclude that a centrosymmetric analysis, such as the MRT analysis, will not give

the correct picture of the exchange flux mechanism.

The angular density functions(ADF) of the sulfite ion in aqueous solution of OSO3─ S···Ow,

Figure 7. For the oxygens OB, interacting with the sulfite oxygens, OSO3 there are three distinct

maxima at 36, 77, 130 , Figure 7 c. In contrast the OA oxygens interacting with the sulfur only has

a minor distinctive peak at 48 degrees and then a broad band covering the mayor part of the angular

10

space, Figure 7 b. This implicates that there is a higher order of the water molecules clustered

around the OSO3 than for the water molecules clustered outside the lone electron pair on the sulfur

atom. Examining the tilt for the sulfite OSO3···Ow bond Figure 8a we can see that there is a slight

out-of-plane tilt of the angle ±30 degrees which means that the orientation of the bond to the OSO3 is

mostly in-plane-oriented which is consistent with hydrogen bonding of the water molecules.

Furthermore the dipole angle of sulfite oxygens to water, Figure 8b, the orientation is limited to

three peaks at 30, 135 and 155. The 30 degree peak is consistent with waters in the transition area

and the other two peaks represent an orientation consistent with hydrogen bonding.

A comparison of first shell MRT for sulfate, phosphate, sulfite and bulk water at Hartree-

Fock level is presented in Table 2. The residence time of the first shell of water molecules of the

hydrated sulfite ion is, 3.2 ps, which is intermediate of the sulfate ion, 2.6 ps, and the phosphate ion,

3.9 ps,2,3,15 By calculating the sustainability coefficient, which is the number of exchange events

longer than 0.5 ps over the total number of events, Sex = N0.5ex/N0.0

ex = 0.171. For pure water22,23 Sex

= 0.089 making the hydration shell about twice as stable as that of pure water. This structure

making ability is concurrent with previous reports calculated on the free energy of hydrogen bonds

based on the viscosity coeficients.4,5 The MRT and the Sex are inherently symmetric and the

behavior of the sulfite ions hydration is asymmetric. This generates a problem when comparing

symmetrically behaving ions with asymmetric ones since almost all flux water exchange takes place

through the water molecules clustered outside the lone pair side and almost no exchange takes place

outside this region. This means that the rate determining step might not be the exchange between

hydration shell and bulk but rather the transfer of water molecules inside the hydration shell, while

for a symmetric system, such as hydration of sulfate ion, the water exchange mechanism takes place

directly between a water molecule hydrogen bound to the sulfate oxygen and a bulk water molecule.

Conclusions

The sulfite ion has an asymmetric hydration sphere with three water molecules hydrogen bound

to each sulfite of the oxygen, and with 3-4 water molecules clustered outside the lone electron-pair.

The spatial density plot, Figure 9, illustrate that there is a considerable asymmetry in the hydration

sphere generated by the lone pair. An angular radial distribution (ARD) analysis did show that the

11

water exchange rate of the water molecules hydrogen bound to sulfite oxygens is very slow within

the time of the simulation, 20 ps, except for a minor exchange taking place diametrically opposite to

the lone electron pair. The water exchange of hydrated water molecules takes in principle only place

between the water molecules clustered outside the lone electron-pair and the aqueous bulk. The

water molecules hydrogen bound to the sulfite oxygens can be transferred to the region of the lone

electron-pair, and there be exchanged. On the other hand, in the hydrated sulfate ion, with higher

symmetry, the water molecules, hydrogen bound in the very same way as in the sulfite ion, are

readily exchanged directed with surrounding bulk water molecules in a completely different

mechanism.

Acknowledgments

We gratefully acknowledge the financial support from the Swedish Research Council and the

Austrian Science Foundation.

Supporting Information Available: Additional information as noted in the text and a complete

reference 16. This material is available free of charge via the Internet at http://pubs.acs.org.

12

References

(1) The United States Patent and Trademark Office (USPTO). http://www.uspto.gov/index.jsp

(accessed Dec 3, 2010)

(2) Vchirawongkwin, V.; Rode, B. M.; Persson, I. J. Phys. Chem. B 2007, 111, 4150-4155.

(3) Marcus, Y. J Solution Chem. 1994, 23, 831-848.

(4) Marcus, Y. Chem. Rev. 2009, 109, 1346-1370.

(5) Stålhandske, C. M. V.; Persson, I.; Sandström, M.; Kamienska-Piotrowicz, E. Inorg. Chem.

1997, 36, 3174-3182.

(6) Johansson, G.; Sandström, M. Chem. Scr. 1973, 4, 195-198.

(7) Molund, M.; Persson, I. Chem. Scr. 1985, 25, 197-197.

(8) Chandler, J. P. Behavioral Science 1969, 14, 81-82.

(9) Wilson, A. J. C., Ed. International Tables for Crystallography; Kluwer Academic Publishers:

Dordrecht, The Netherlands, 1995; Vol. C.

(10) Cromer, D. T. J. Chem. Phys. 1969, 50, 4857-4879.

(11) Cromer, D. T. J. Chem. Phys. 1967, 47, 1892-1893.

(12) Bopp, P.; Jancsó, G.; Heinzinger, K. Chem. Phys. Lett. 1983, 98, 129-133.

(13) Rode, B.; Hofer, T.; Randolf, B.; Schwenk, C.; Xenides, D.; Vchirawongkwin, V. Theoretical

Chemistry Accounts: Theory, Computation, and Modeling (Theor. Chim. Acta) 2006, 115, 77-

85.

(14) Hofer, T. S.; Pribil, A. B.; Randolf, B. R.; Rode, B. M. In Combining Quantum Mechanics

and Molecular Mechanics. Some Recent Progresses in QM/MM Methods; Academic Press,

2010; Vol. 59, pp. 213-246.

(15) Pribil, A. B.; Hofer, T. S.; Randolf, B. R.; Rode, B. M. J. Comput. Chem. 2008, 29, 2330-

2334.

(16) Frisch, M. J. et al. Gaussian 03, Revision E.01.

(17) Berendsen, H. J. C.; Grigera, J. R.; Straatsma, T. P. J. Phys. Chem. 1987, 91, 6269-6271.

(18) Dunning, T. H. J. Chem. Phys. 1970, 53, 2823-2833.

(19) Magnusson, E.; Schaefer, H. F. J. Chem. Phys. 1985, 83, 5721-5726.

(20) Ahlrichs, R.; Bä, M.; Häser, M.; Horn, H.; Kölmel C. ; Chem. Phys. Lett. 1989, 162, 165-169.

(21) Torapava, N.; Persson, I.; Eriksson. L.; Lundberg, D. Inorg. Chem. 2009, 48, 11712-11723.

(22) Hofer, T. S.; Tran, H. T.; Schwenk, C. F.; Rode, B. M. J. Comput. Chem. 2004, 25, 211-217.

(23) Xenides, D.; Randolf, B. R.; Rode, B. M. J. Chem. Phys. 2005, 122, 174506.

13

Table 1. The distances determined for the different model atom complexes in LAXS experiments

followed by the center and fwhh of the analytical peaks found in RDF from simulation.

Complex Distance(Å) fwhh Method

S−OSO3 1.53 0.128 LAXS

S∙∙∙Ow 3.68 0.219

S∙∙∙Olp 4.16 0.232

water(Ow∙∙∙Ow) 2.878 0.210

Na∙∙∙Ow 2.407 0.224

O-H 0.98 0.058 QMCF

S-OSO3 1.53 0.074

Bulk water Ow∙∙∙H 1.921 0.418

water(Ow∙∙∙Ow) 2.828 0.299

OSO3∙∙∙Ow 2.770 0.340

S∙∙∙Ow 3.73 0.530

S∙∙∙Olp 4.11 0.370

Table 2. Mean residence times, MRTs, and the sustainability coefficients, Sex, of water molecules in the hydrated sulfite, sulfate, phosphate ions and in bulk water from simulations on HF theory level.

Solvated ion τ0.5 Nex0.5 Nex

0.0 1/Sex Reference

Sulfite 3.2 59 346 5.9 This work

Sulfate 2.6 54 399 7.4 15

Phosphate 3.9 42 132 3.1 10

Bulk water 1.7 24 269 11.2 16

14

Legends to Figures

Figure 1. Describing the hemispherical portioning of water oxygens based on the dipole vector of

the sulfite ion in aqeous solution

Figure 2. LAXS. (a) The individual peak shapes for all contributing species in the 1.5987

mol∙dm-3 aqueous solution of sodium sulfite: the hydrated sulfite ion (orange line), the

hydrated sodium ion (brown line), and aqueous bulk (green line). (b) Experimental D(r)

– 4�r2ρo (black line); model (red line), the modelled distances are given in table 1;

difference (blue line). (c) Reduced LAXS intensity function, s·iexp(s) (black line); model

s·icalc(s) (red line).

Figure 3. RDF’s constructed from simulation data, a) linear summation of b)-e), b) S···H distances,

c) O-H distances, d) S-O distances, the gray help lines shows N= 3 and 12 which

corresponds to ionic oxygens and coordinated oxygens, e) O∙∙∙O. Subplots b.1) to e.1)

show the interesting regions in more detail. In e.1) three different contributions red, blue

and green reperesenting total O∙∙∙O, Ow∙∙∙Ow and OSO3∙∙∙Ow respectively, the OSO3∙∙∙Ow

curve(green line) is scaled 300 times.

Figure 4 CND, coordination number distribution. The CN numbers calculated from mean

residence time at the HF level, The HF level always over estimates CN and the average

CN 12.48 well agrees with the experimental value.

Figure 5. Contour plots of sulfur centered Angular Radial Distribution (ARD) functions, showing

oxygens top left, hydrogen top right, and superimposed image. The superimposed image

shows that the hydrogens of coordinated waters are oriented inwards, and the intensity

of the path of exchange can be seen as dark blue intensity indicating zero in the

normalized distribution function, i.e. no atoms are encountered, while brighter colors

represents a non zero value.

Figure 6 Mesh plots viewed along the z axis showing water oxygen occupancy of sulfite, sulfate

ion. The occupancy of a given angle, distance pair is given by intensity of the colors

ranging from no occupancy, black, low medium occupancy, blue, to high occupancy

yellow or red. The zero points are equal in intensity, the zero-point alignment shows the

difference in transportation properties as one can determine which regions contain no

exchange events

15

Figure 7. ADF:s, angular distribution functions, The Angular distribution over the simulation for

the angle between the vectors as described by the figures adjacent to each curve for case

a,b and c. The ADF:s show that there is a preferred region of occupancy for water

molecules in the first hydration shell.

Figure 8. The tilt, out of plane angle of the OsOw vector, show that there is two preferred angle

ranges 30° out of plane on both sides of the plane and the Θ, angle of dipole moment

vector and the OsOw vector, show preference of 4 angular states during a time average

for the water molecules over the simultation.

Figure 9. Density plots generated using a rotating box and fixed axes. The density plot illustrates

the cavity created in the solution around the sulfite ion

16

Figure 1

17

Figure 2

a)

b)

c)

18

Figure 3

a)

b)

c)

d)

e) e.1)

d.1)

c.1)

b.1)

19

Figure 4

N

%

20

Figure 5

21

Figure 6

r(Å) r(Å)

r(Å)

22

Figure 7

Angle/° S-OSO3∙∙∙Ow

%

a)

b)

c)

23

Figure 8

b) a)

24

Figure 9

25

Graphical Abstract

Synopsis

The sulfite ion has an asymmetric hydration sphere with three water molecules are hydrogen bound to each of the sulfite oxygen, and with 3-4 water molecules clustered outside the lone electron-pair. An angular radial distribution analysis has shown that the water exchange takes only place between the water molecules clustered outside the lone electron-pair and the aqueous bulk. This is opposite to the hydrated sulfate ion where the water molecules, symmetrically hydrogen bound to the sulfate oxygens, exchange directly with the aqueous bulk.

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1

A Comparative Structural Study of Sodium Selenite and Selenate Using

Large Angle X-ray Scattering and Double Difference Infrared Spectroscopy

Lars Eklund and Ingmar Persson

Department of Chemistry, Swedish University of Agricultural Sciences, P.O.Box 7015, SE-

750 07 Uppsala, Sweden.

Graphical Abstract

Synopsis

The structures of the hydrated selenite and selenate ions have been studied in aqueous

solution by LAXS and DDIR. The Se-O bond distances are 1.709(2) and 1.657(2) Å,

respectively, which are slightly longer than the mean distances found in the solid state. Each

of the selenite and selenate oxygens hydrogen binds on average 2.5 and two water molecules,

respectively, which is a lower number than observed for the sulfite and sulfate ions, three. In

addition, ca. three water molecules are clustered outside the lone electron-pair on selenium at

long distance, 4.3 Å, as also found for the sulfite ion, showing asymmetric hydration for the

selenite ion.

2

Abstract

The structures of the hydrated selenite and selenate ions have been studied in aqueous

solution by large angle X-ray scattering, LAXS, and double difference infrared (DDIR)

spectroscopy. The Se-O bond distances are 1.709(2) and 1.657(2) Å, respectively, which are

slightly longer than the mean distances found in the solid state. The distances found for the

first hydration shell of hydrated selenite ion were 3.87(2) Å for Se∙∙∙Ow, and 4.36(4) Å for the

waters clustered outside the selenium lone electron-pair. The selenate ion has a symmetric

hydration shell with only one distance, Se∙∙∙Ow, 3.94(2) Å. The O∙∙∙O distances for the selenite

and selenate oxygens to water oxygens, O∙∙∙Ow, were not distinguishable from the Ow∙∙∙Ow

distance in the aqueous bulk, giving mean values of 2.873(4) and 2.861(4) Å, respectively.

Assuming a mean Ow∙∙∙Ow distance in the aqueous bulk of 2.89 Å, an estimated O∙∙∙Ow

distance of 2.83-2.86 and 2.81-2.85 Å for the selenite and selenate ions is obtained,

respectively. The mean Se-O∙∙∙Ow angle is 114.5 and 120 o for the selenite and selenate ions,

respectively. The double difference infrared (DDIR) spectra show peaks for affected water

bound to the selenite and selenate ions at 2491±2 cm-1 and 2480±39 cm-1, respectively. As

these are observed below the peak of bulk water, 2509 cm-1, the selenite and selenite ions are

both regarded as weak structure makers.

3

Introduction

The selenium oxo acids and their salts have many similarities with the corresponding sulfur

oxo acids, including similar physico-chemical parameters.1 The structure and hydrogen

bonding of the hydrated sulfite and sulfate ions has been studied previously.2-4 Three water

molecules are hydrogen bound to each oxygen atom in both ions. Furthermore, some water

molecules are clustered outside the lone electron-pair of the sulfite ion at a fairly well-defined

distance. The sulfite and sulfate ions are both weak structure makers, thus the hydrogen bond

between the sulfite/sulfate oxygens and the hydrating water molecules is slightly shorter and

stronger than between water molecules in the aqueous bulk. It is of fundamental interest to

compare the hydration of the corresponding selenium oxo anions with the sulfur ones from

both structural and hydrogen bond strength point of view. An overview of the structures of the

selenous acid-hydrogenselenite ion-selenite ion and the selenic acid-hydrogenselenate ion-

selenate ion system will be presented and analyzed.

Experimental

Chemicals. Sodium selenate, Na2SeO4 (analytical grade, Fluka), sodium selenite, Na2SeO3

(analytical grade, Fluka) and heavy water, D2O, (99.96 atom % D, Aldrich) were used without

further purification.

Solutions. The solutions for the LAXS experiments were prepared by dissolving weighed

amount of sodium selenite and selenate, respectively, in deionized Milli Q filtered water. The

compositions of the studied solutions are given in Table 1.

For IR measurements matched concentration series in both pure water and 4% w/w D2O/H2O

where prepared for both sodium selenate and sodium selenite.

LAXS. The scattering of MoKα X-ray radiation, λ=0.7107 Å, from the free surface of the

aqueous sodium selenite and selenate solutions were measured in a large angle Θ-Θ goino-

meter described elsewhere.5 The solution was contained in a teflon cup filled until a positive

meniscus was observed generating a flat surface in the irradiated region. The container was

placed inside an air-tight radiation shield with beryllium windows. The scattered radiation

was monchromatised using a LiF (200) single crystal focusing monochromator. The scattering

was determined at 446 angles in the angle range of 0.5 < Θ < 65º, where the scattering angle

is 2 Θ. At each angle 100,000 X-ray quanta where accumulated, and the entire angle range

was scanned twice corresponding to a statistical error of about 0.3 %. The divergence of the

x-rays was defined through combination of divergence-collecting-focal slits of ¼ o-½ o-0.2

4

mm and 1 o-2 o-0.2 mm. Three different Θ-regions were scanned to get a suitable counting rate

and change in angle, with overlapping regions to enable scaling of the data. The data

collection and treatment is described in detail elsewhere.5 All data treatment was carried out

using the KURVLR program,6 and the structural parameters in the theoretical model where

refined by minimizing U = w(s)Σs2[iexp(s)-icalc(s)]² using the STEPLR program.7,8 The

experimental data was normalized to a stoichiometric unit containing one selenium atom,

using the scattering factors f for neutral atoms, including corrections for anomalous

dispersion, Δf' and Δf'', 9 Compton scattering10,11 and multiple scattering events.

Double differential FTIR. The IR measurements were performed in a continuous series on a

Perklin-Elmer Spectrum 100 FT-IR Spectrophotometer with matched concentrations of the

two solutions in a temperature controlled liquid cell using 3mm CaF2 windows (PIKE

Technologies), the cell was heated to 25ºC ± 0.5 ºC.

Each spectrum was measured for 256 scans with 4 cm-1 resolution in the range 4000-900 cm-1.

The path length was 0.035280 mm determined through interference.12 By measuring the same

concentration of salt in both H2O and HDO solution and then subtracting pure solutions

without solute one gets an infrared spectrum of the HDO molecules different from those in the

aqueous bulk. By taking the derivative of these spectra Ϭϵ/Ϭm where ϵ is the spectra and m

the molality of the solution then subtracting (1/N*M)*Ϭϵ/Ϭm from the spectrum of pure

water, where N is the affected number of water and M is the mean molar mass in kg/mol of

water and partially heavy water, as described by Kristiansson et al. and in Gampe et al.,13,14,15

the affected water peaks ascribed to water molecules bound to cations or anions can be found

through PCA. All calculations of the spectra was carried out using GRAMS AI version 8.0

(Thermo-Fisher Scientific) and RAZOR tools(Spectrum Square Associates), and the Array

Basic program YANUZ.AB16 was used to calculate derivatives of spectra.

Results and Discussion

Large angle X-ray scattering

The experimental radial distribution function (RDF) of the aqueous solution of sodium

selenate shows three peaks at 1.657(4), 2.861(8) and 3.94(4) Å, after refinement,

corresponding the Se-O bond distance in the hydrated selenate ion, the O∙∙∙O distances in the

aqueous bulk and between selenate oxygens and hydrating water molecules, and Se∙∙∙O

distances between selenium atom and the hydrating water molecules, respectively, Figure 1.

5

The hydrated sodium ion is observed as a weak shoulder at 2.43(4) Å, after refinement, Figure

1, is in complete agreement with previous studies.17 The observed Se-O bond distance in

aqueous solution is slightly longer, 0.023 Å than the mean Se-O bond distance in solid

selenate salts, Table S1. This is within the expected range as the hydration through the

hydrogen bonding electrostatically interact with the selenate oxygens. The increase in the Se-

O bond length is the same order as previously observed for the sulfate and perchlorate ions.2,18

The distance between the central Se atom the oxygens of the hydrating water molecules,

Se∙∙∙Oaq, 3.94 Å, shows that the �Se-O-Oaq angle of 120 o assuming an O∙∙∙Oaq distance of

2.83 Å (see below). As the water molecules hydrating the selenate oxygens are electrostatic

the �Se-O-Oaq angle of 120 o strongly indicates that on average two water molecules are

hydrogen bound to each selenate oxygen. This is in contradiction to the sulfate and

perchlorate ions where three water molecules are hydrogen bound to each sulfate and

perchlorate oxygen. The O∙∙∙O distances in the aqueous bulk and between selenate oxygens

and hydrating water molecules are not possible to separate, and a mean O∙∙∙O distance of

2.861(8) Å was obtained. This mean O∙∙∙O distance is slightly shorter than normally observed

for the aqueous bulk, 2.89 Å. This strongly indicates that the O∙∙∙Oaq distance is in the range

2.81-2.85 Å, showing that the selenate ion is a structure maker as also shown in the DDIR

measurements, see below.

The RDF of the aqueous solution of sodium selenite shows three peaks at 1.709(4),

2.873(8) and 3.87(4) Å, after refinement, corresponding the Se-O bond distance in the

hydrated selenite ion, the Oaq∙∙∙Oaq and O∙∙∙Oaq distances, and Se∙∙∙O distances between

selenium atom the hydrating water molecules, respectively, Figure 2. The latter peak is

unusually broad strongly indicating an additional Se∙∙∙O distance at 4.36(8) Å, as also found in

the hydrated sulfite ion.4 Assuming an O∙∙∙Oaq distance of 2.85 Å, see below, the �Se-O-Oaq

angle becomes 114 o, thus between the expected values of 109.47 and 120.0 for tetrahedral

and trigonal configuration around the selenite oxygens. Furthermore, the temperature

coefficient is very large, twice the value observed for the selenate ion, Table 2, which shows a

very broad distance distribution. It seems therefore likely that the selenite oxygen hydrogen

bind to two or three water molecules, and that the observed Se∙∙∙Oaq distance and the large

temperature coefficient are average values. The additional Se∙∙∙Oaq distance at 4.36(8) Å does

most probably belong to the water molecules clustered outside the lone electron-pair on the

selenium.

The mean value of the O∙∙∙O distance in the aqueous bulk and between selenate oxygens

6

and hydrating is slightly shorter, 2.873(4) Å, than in the aqueous bulk, 2.89 Å. The observed

mean O∙∙∙O distance indicate that the O∙∙∙Oaq distance is in the range 2.83-2.86 Å, showing

that the selenate ion is a structure maker but as such weaker than the selenate ion as also

shown in the DDIR measurements, see below.

Fourier transform infrared spectroscopy

Analysis of the affected spectra of selenite, Figure 3, through spectral decomposition

generates number of affected waters as N=15.7 and a sodium peak at 2534±9 cm-1 in good

agreement with earlier work.15,19,20,21,22,23 The main anionic peak of the hydrated selenite ion

is at 2491±2 cm-1. The position of the anionic peak indicates that selenite ion is a weak

structure maker with molecular interaction energy of water ΔUw= -45.2 kJ mol-1 derived from

υOD using the Badger-Bauer rule 24 and the calculations detailed in earlier work14,15

The selenate affected DDIR spectra are given in Figure 4, and it was possible to separate the

contributions from the sodium and selenate ions. The peak ascribed to the selenate ion has a

maximum at 2480±39 cm-1. Transforming the υOD for the affected water peak to molecular

interaction energy of water ΔUw= -47.4 kJ∙mol-1calulated as above. The peak ascribed to the

sodium ion is observed at 2539±18 cm-1. The peak is a slightly wider peak than earlier work,

but the peak position is within expected range.

Structure of selenate and selenite ions in solid state and aqueous solution

The Se-O bond distances in available data bases for the selenous acid-hydrogenselenite ion-

selenite ion and the selenic acid-hydrogenselenate ion-selenate ion systems are summarized in

Table S1. The selenite and selenate ions have regular truncated tetrahedral and tetrahedral

structure, respectively, with all Se-O bond distances the same or almost the same, mean 1.691

and 1.634 Å, Table S1. As shown above, the Se-O bond distances increase by about 0.02 Å at

hydration in aqueous solution. The structures of selenous acid, hydrogenselenite ion, selenic

acid and hydrogenselenate ion display a different pattern with the Se-O bonds where the

oxygen is protonated significantly longer than oxygens without any proton. The difference in

mean Se-O bond distance in these two kinds of oxygens in the hydrogenselenite and hydro-

genselenate ions is 0.107 and 0.090 Å, respectively, and about the same differences are found

for the selenous and selenic acid, 0.118 and 0.089 Å, respectively. This difference is expected

to be maintained also in aqueous solution as the difference in hydrogen bond strength when

the selenite/selenate oxygen is a hydrogen bond acceptor or the OH group as a hydrogen bond

donor is expected to be small. It is not possible to distinguish such small differences with the

7

structural methods applicable on aqueous solution available today. However, the mean Se-O

bond distance for the hydrogenselenite ion, selenous acid, hydrogenselenate ion and selenic

acid is very close to the mean Se-O bond distance in the selenite and selenate ions with 1.691,

1.699 and 1.700 Å for SeO32-, HSeO3

- and H2SeO3, respectively, and 1.634, 1.638 and 1.642

Å for SeO42-, HSeO4

- and H2SeO4, respectively, Table S1.

Conclusions

The structures of the hydrated selenite and selenate ions in aqueous solution show a single

shell of water molecules hydrogen bound to the oxygen atoms. In addition, outside the lone

electron-pair of the selenite ion about three water molecules are clustered at long distance. To

the oxygens of the hydrated selenite and selenate ions on average ca. 7.5 and eight water

molecules are coordinated, respectively. These numbers are lower than for the corresponding

sulfuroxo-anions where three water molecules are hydrogen bound to each of the oxygen.

Additionally around the selenium lone-pair of selenite three water molecules are clustered at a

longer distance. Selenite and selenate ions are both weak structure makers as shown by O-D

stretching frequencies of the hydrating water molecules in comparison with the value in pure

water. The symmetric and more oxidized selenate is a stronger structure maker than selenite

but a weaker than the sulfate and fluoride anions4, 23. For more information on the influence of

asymmetric hydration mechanism of the selenite ion on the difference in coordination further

studies using computer simulations would be needed.

Acknowledgment

The financial support from the Swedish Research Council is gratefully acknowledged.

8

References

1. Greenwood, N. N.; Earnshaw, A. The Chemistry of the Elements, 2nd Ed., Elsevier,

Oxford, Chap. 16.2.6.

2. Vchirawongkwin, V.; Rode; B. M.; Persson, I. J. Phys. Chem. B 2007, 111, 4150-4155.

3. Bergström, P.-Å.; Lindgren, J.; Kristiansson, O. J. Phys. Chem. 1991, 95, 8575-8580.

4. Eklund, L. ; Hofer, T. S. ; Pribil, A. ; Rode, B. M. ; Persson, I., submitted for publication

to Inorg. Chem.

5. Stålhandske, C. M. V.; Persson, I.; Sandström, M.; Kamienska-Piotrowicz, E. Inorg.

Chem. 1997, 36, 3174-3182.

6. Johansson, G.; Sandström, M. Chem. Scr. 1973, 4, 195.

7. Molund, M.; Persson, I. Chem. Scr. 1985, 25, 197.

8. Chandler, J. P. Behav. Sci. 1969, 14, 81-82.

9. Wilson, Ed. International Tables for Crystallography; Kluwer Academic Publishers:

Dordrecht, The Netherlands, 1995; Vol. C.

10. Cromer, D. T. J. Chem. Phys. 1967, 47, 1892-1894.

11. Cromer, D. T. J. Chem. Phys. 1969, 50, 4857-4859.

12. Pike Technologies application note -0501.

13. Kristiansson, O.; Lindgren, J.; De Villepin, J. J. Phys. Chem. 1988, 92, 2680-2685

14. Stangret, J.; Gampe, T. J. Phys. Chem. 1999, 103, 3778-3783.

15. Stangret, J.; Gampe, T. J. Phys. Chem. A 2002, 106, 5393-5402.

16. Array Basic program YANUZ.AB provided by M. Smiechowski, Technical University of

Gdansk, Poland

17. Mähler, J.; Persson, I., submitted to J. Am. Chem. Soc.

18. Persson, I.; Lyczko, K.; Lundberg, D.; Eriksson, L.; Placzek, A. Inorg. Chem. 2011, 50,

1058-1072.

19. Eriksson, A.; Kristiansson, O.; Lindgren, J. J. Mol. Struct. 1984, 114, 455.

20. Stangret, J.; Kamien´ska-Piotrowicz, E. J. Chem. Soc., Faraday Trans. 1997, 93, 3463.

21. Lindgren, J.; Kristiansson, O.; Paluszkiewicz, C. Interactions of Water in Ionic and

Nonionic Hydrates; Kleeberg, H., Ed.; Springer-Verlag: Berlin, Heidelberg, 1987; p 43.

22. Kristiansson, O.; Eriksson, A.; Lindgren, J. Acta Chem. Scand. 1984, A38, 613

23. Kristiansson, O.; Lindgren, J. J. Mol. Struct., 1988, 177, 537.

24. Badger, R. M.; Bauer, S. H. J. Chem. Phys. 1937, 5, 839-851.

9

Table 1. Concentrations (mol�dm-3) of the aqueous sodium selenite and selenate solutions

used in the LAXS measurements.

Sample [SeOx2-] [Na+] [water] �/g�cm-3 �/cm-1

Na2SeO3 in water 1.5006 3.0012 49.2073 1.170 10.27

Na2SeO4 in water 1.5066 3.0132 50.2768 1.1904 10.33

Table 2. Mean bond distances, d/Å, number of distances, N, and temperature coefficients,

b/Å2, the half-height full width, l/Å, in the LAXS study of aqueous sodium selenite and

selenate solutions at room temperature.

Species Interaction N d b l

1.5066 mol·dm-3 Na2SeO4 in water

[SeO4(H2O)12]2- Se-O 4 1.657(2) 0.0022(3) 0.21

Se···OII 8 3.94(2) 0.028(2) 0.24

Na(H2O)6+ Na-O 6 2.43(2) 0.022(2) 0.21

Aqueous bulk O···O 2 2.861(4) 0.018(4) 0.19

1.5006 mol·dm-3 Na2SeO3 in water

[SeO3(H2O)9(H2O)~3]2- Se-O 3 1.709(2) 0.0031(3) 0.079

Se···OII 7.5 3.87(2) 0.050(2) 0.33

Se···OII ~3 4.36(4) 0.027(2) 0.23

Na(H2O)6+ Na-O 6 2.42(2) 0.023(2) 0.21

Aqueous bulk O···O 2 2.873(4) 0.025(1) 0.22

10

Table 3. O-D stretching frequencies of the water molecules

hydrating the selenate, sulfate, selenite and sulfite ions.

Ion �(O-D)/cm-1 Ref.

[SeO3(H2O)9(H2O)~3]2- TBD a

[SeO3(H2O)7.5(H2O)~3]2- 2491 a

[SO4(H2O)12]2- 2477 3

[SeO4(H2O)8]2- 2480 a

a This work.

11

Legends to Figures

Figure 1 LAXS. SeO42-(aq) (a) Individual peak shapes for all theoretical contributing specis

in the 1.5006 mol•dm-3aqeous solution of hydrated selenate. The hydrated selenate ion (blue

line), hydrated sodium ion(purple line) and the aqueous bulk (green line). (b) Experimental

D(r) - 4Πr2ρ0 (blue line); model (purple line),the modelled distances are given in table 1;

difference (green line). (c) Reduced LAXS intensity function, si(s) (blue line); model sicalc(s)

(purple line).

Figure 2 LAXS SeO32-(aq). (a) Individual peak shapes for all theoretical contributing specis

in the 1.5006 mol•dm-3aqeous solution of hydrated selenite, the hydrated selenite ion (blue

line), hydrated sodium ion(black line) and the aqueous bulk (red line). (b) Experimental D(r) -

4Πr2ρ0 (blue line); model (red line),the modelled distances are given in table 1; difference

(green line). (c) Reduced LAXS intensity function, si(s) (blue line); model sicalc(s) (purple

line).

Figure 3 Double differential FTIR SeO32-(aq). By PCA analysis using gaussian peak shapes

of the affected spectra. The analytical peaks could be found at the affected spectra (black)

where N=15.7, the anionic peaks yellow and green at 2408±6 and 2491±2, where yellow

represents the asymmetric contributions. The sodium peak is represented by represents the

red main peak at 2534 ± 9 and peak number blue at 2656 ± 2 which is well in agreement with

earlier work. The tail at lower wavenumbers than 2300 is not associated with the O-D stretch

of affected water.

12

Figure 4 Double differential FTIR SeO42-(aq). By PCA analysis using gaussian peak shapes

of the affected spectra. The analytical peaks could be found at the affected spectra (black)

where N=12.9, the anionic peaks green, purple and yellow, where purple and yellow

represents the asymmetric contributions. For the sodium peak red represents the main peak

which is well in agreement with erlier work and the blue is a asymmetric peak cointribution.

13

Figure 1

-15

-10

-5

0

5

10

15

20

25

30

0 1 2 3 4 5 6 7 8 9 10

r /Å

(D (r )-4�r 2� o)·10-3/e2·Å-1

-1

-0.5

0

0.5

1

0 2 4 6 8 10 12 14 16

s ·i (s )·10-3/e.u.·Å-1

s /Å-1

a)

b)

c)

14

Figure 2

-15

-10

-5

0

5

10

15

20

25

30

0 1 2 3 4 5 6 7 8 9 10

(D (r )-4�r 2� o)·10-3/e2·Å-1

r /Å

-1.0

-0.5

0.0

0.5

1.0

0 2 4 6 8 10 12 14 16

s ·i (s )·10-3/e.u.·Å-1

s /Å-1

a)

b)

c)

15

Figure 3

Figure 4

16

Tab

le S

1. S

umm

ary

of S

e-O

bon

d di

stan

ces s

olid

stat

e st

ruct

ures

of s

elen

ate

ion,

hyd

roge

nsel

enat

e io

n, se

leni

c ac

id, s

elen

ite io

n,

hydr

ogen

sele

nite

and

sele

nous

aci

d fr

om th

e In

orga

nic

Cry

stal

Stru

ctur

e D

atab

ase

(IC

SD) a

nd C

ambr

idge

Stru

ctur

e D

atab

ase

(CSD

). R

efer

ence

s in

red

are

not i

nclu

ded

in th

e av

erag

e va

lue.

Sele

nate

ion,

SeO

42-

ICSD

/ C

SD c

ode

d(Se

-O)/Å

R

efer

ence

For

mul

a of

com

poun

d 73

411

1.

600

Å

Fabr

y, J.

; Bre

czew

ski,

T. A

cta

Cry

stal

logr

., Se

ct. C

199

3, 4

9, 1

724-

1727

. Tl

2SeO

4

4197

75

1.61

7 Å

G

rzec

hnik

, A.;

Bre

czew

ski,

T.; F

riese

, K. J

. Sol

id S

tate

Che

m. 2

008,

181

, 291

4-29

17.

Tl2S

eO4

9938

2

1.61

8 Å

Fr

iese

, K.;

Goe

ta, A

. E.;

Leec

h, M

. A.;

How

ard,

J. A

. K.;

Mad

aria

ga, G

.; Pe

rez-

Mat

o, J.

M.;

Bre

czew

ski,

T. J

. Sol

id S

tate

Che

m. 2

004,

177

, 112

7-11

36.

Tl2S

eO4

2104

7

1.62

0 Å

K

rugl

ik, A

. I.;

Sim

onov

, V. I

.; Y

uzva

k, V

. I. K

rist

allo

graf

iya

1973

, 18N

, 287

-292

. (N

H4)

NaS

eO4∙2

H2O

1573

71

1.62

0 Å

D

amm

ak, M

.; Li

taie

m, H

.; G

rave

reau

, P.;

Mhi

ri, T

.; K

olsi

, A. W

. J. A

lloys

Com

pd. 2

007,

442

, 316

-31

9. R

b 2Se

O4∙T

e(O

H) 6

4193

38

1.62

1 Å

G

hedi

a, S

.; D

inne

bier

, R.;

Jans

en, M

. Sol

id S

tate

Sci

. 200

9, 1

1, 7

2-76

. R

b 2Se

O4

1429

8

1.62

2 Å

K

alm

an, A

.; St

ephe

ns, J

. S.;

Cru

icks

hank

, D. W

. J. A

cta

Cry

stal

logr

., Se

ct. B

197

0, 2

6, 1

451-

1454

. K

2SeO

4

1076

20

1.62

2 Å

M

alch

us, M

.; Ja

nsen

, M. Z

. Nat

urfo

rsch

., Te

il B

1998

, 53,

704

-710

. (N

(CH

3)4)

2SeO

4

2005

39

1.62

2 Å

N

ozik

, Y. Z

.; Fy

kin,

L. E

.; D

uder

ov, V

. Y.;

Mur

adya

n, L

. A.;

Ros

tunt

seva

, A. I

. Kri

stal

logr

afiy

a 19

78,

23N

, 617

-619

. N

a(N

H4)

SeO

4∙2H

2O

7346

4

1.62

4 Å

Fa

bry,

J.; B

recz

ewsk

i, T.

; Pet

ricek

, V. A

cta

Cry

stal

logr

., Se

ct. B

199

3, 4

9, 8

26-8

32.

K3N

a(Se

O4)

2

8168

8

1.62

4 Å

G

onza

lez-

Silg

o, C

.; So

lans

, X.;

Rui

z-Pe

rez,

C.;

Mar

tinez

-Sar

rion,

M. L

.; M

estre

s, L.

Fer

roel

ectr

ics

1996

, 177

, 191

-199

. K

2SeO

4

9938

3

1.62

5 Å

Fr

iese

, K.;

Goe

ta, A

. E.;

Leec

h, M

. A.;

How

ard,

J. A

. K.;

Mad

aria

ga, G

.; Pe

rez-

Mat

o, J.

M.;

17

Bre

czew

ski,

T. J

. Sol

id S

tate

Che

m. 2

004,

177

, 112

7-11

36.

Tl2S

eO4

8168

9

1.62

6 Å

G

onza

lez-

Silg

o, C

.; So

lans

, X.;

Rui

z-Pe

rez,

C.;

Mar

tinez

-Sar

rion,

M. L

.; M

estre

s, L.

Fer

roel

ectr

ics

1996

, 177

, 191

-199

. K

2SeO

4

8169

0

1.62

6 Å

G

onza

lez-

Silg

o, C

.; So

lans

, X.;

Rui

z-Pe

rez,

C.;

Mar

tinez

-Sar

rion,

M. L

.; M

estre

s, L.

Fer

roel

ectr

ics

1996

, 177

, 191

-199

. K

2SeO

4

5416

8

1.62

7 Å

Fu

kam

i, T.

; Che

n, R

.-H. A

cta

Phys

. Pol

., Se

r. A

1998

, 94,

795

-801

. K

3Na(

SeO

4)2

1587

90

1.62

8 Å

K

rivov

iche

v, S

. V. U

krai

n. D

okl.

Kri

stal

logr

. 200

6, 1

35, 1

06-1

13.

[Al(H

2O) 6

] 2(S

eO4)

3(N

O3)

∙4H

2O

2503

16

1.62

8 Å

K

rivov

iche

v, S

. V. Z

apis

ki V

sero

ssijs

kogo

Min

eral

ogic

hesk

ogo

Obs

hche

stva

200

6, 1

35, 1

06-1

13.

[Al(H

2O) 6

] 2(S

eO4)

3∙4H

2O

4197

76

1.62

8 Å

G

rzec

hnik

, A.;

Bre

czew

ski,

T.; F

riese

, K. J

. Sol

id S

tate

Che

m. 2

008,

181

, 291

4-29

17.

Tl2S

eO4

8169

1

1.63

0 Å

G

onza

lez-

Silg

o, C

.; So

lans

, X.;

Rui

z-Pe

rez,

C.;

Mar

tinez

-Sar

rion,

M. L

.; M

estre

s, L.

Fer

roel

ectr

ics

1996

, 177

, 191

-199

. K

2SeO

4

9451

7

1.63

0 Å

Tr

oyan

ov, S

. I.;

Kos

terin

a, E

. V.;

Kem

nitz

, E. Z

h. N

eorg

. Khi

m. 2

001,

46,

149

6-15

02.

Cs 4

(SeO

4)(H

SeO

4)2∙H

F

1606

81

1.63

0 Å

Sm

irnov

, L. S

.; M

elny

k, G

.; Zi

nk, N

.; W

ozni

ak, K

.; D

omin

iak,

P.;

Paw

luko

jc, A

.; Lo

ose,

A.;

Shuv

alov

, L. A

. Pov

erkh

nost

nye

Fizi

ka, K

him

iya,

Mek

hani

ka 2

007,

73-

79.

(NH

4)2(

SeO

4)2

2812

76

1.63

0 Å

Jo

hnst

on, M

. G.;

Har

rison

, W. T

. A. A

cta

Cry

stal

logr

., Se

ct. E

200

3, 5

9, i2

5-i2

7. L

i 2SeO

4∙H2O

7100

13

1.63

0 Å

Eu

ler,

H.;

Bar

bier

, B.;

Mee

nts,

A.;

Kirf

el, A

. Z. K

rist

allo

gr. -

New

Cry

stal

Str

uct.

2009

, 224

, 360

-364

. Tl

2[Zn

(H2O

) 6](

SeO

4)2

RU

XW

IQ

1.63

0 Å

N

emec

, I.;

Gye

pes,

R.;

Mic

ka, Z

.; Tr

ojan

ek, F

. Mat

. Res

. Soc

. Sym

p. P

roc.

200

2, 7

25, 2

13.

(C5H

12N

O2)

2SeO

4∙2H

2OM

.K.M

arch

ewka

, J.Ja

ncza

k, S

.Deb

rus,

J.Bar

an, H

.Rat

ajcz

ak

6092

8

1.63

1 Å

Ta

kaha

shi,

I.; O

node

ra, A

.; Sh

ioza

ki, Y

. Act

a C

ryst

allo

gr.,

Sect

. C 1

987,

43,

179

-182

. R

b 2Se

O4

7346

3

1.63

1 Å

Fa

bry,

J.; B

recz

ewsk

i, T.

; Pet

ricek

, V. A

cta

Cry

stal

logr

., Se

ct. B

199

3, 4

9, 8

26-8

32.

K3N

a(Se

O4)

2

1500

83

1.63

1 Å

W

ildne

r, M

.; St

oilo

va, D

.; G

eorg

iev,

M.;

Kar

adjo

va, V

. J. M

ol. S

truc

t. 20

04, 7

07, 1

23-1

30.

[Be(

H2O

) 4]S

eO4

18

7100

12

1.63

1 Å

Eu

ler,

H.;

Bar

bier

, B.;

Mee

nts,

A.;

Kirf

el, A

. Z. K

rist

allo

gr. -

New

Cry

stal

Str

uct.

2009

, 224

, 360

-364

. Tl

2[N

i(H2O

) 6](

SeO

4)2

PRA

CSE

10

1.63

1 Å

M

oros

in, B

.; H

owat

son,

J. A

cta

Cry

stal

logr

., Se

ct. B

197

0, 2

6, 2

062.

[C

u(H

2N(C

H2)

NH

2)2]

SeO

4∙H2O

2765

6

1.63

2 Å

M

ehro

tra, B

. N.;

Hah

n, T

.; Ey

sel,

W.;

Roe

pke,

H.;

Illgu

th, A

. Neu

es J

ahrb

uch

fuer

Min

eral

ogie

. M

onat

shef

te 1

978,

408

-421

. N

a 2Se

O4

6118

3

1.63

2 Å

K

rugl

ik, A

. I. D

okl.

Akad

. Nau

k SS

SR 1

976,

229

, 853

-855

. N

a(N

H4)

(SeO

4)∙2

H2O

1584

80

1.63

2 Å

K

rivov

iche

v, S

. V. U

krai

n. D

okl.

Kri

stal

logr

. 200

6, 1

35, 8

0-87

. [M

g(H

2O) 4

] 2(S

eO4)

2∙H2O

2009

12

1.63

2 Å

M

ukht

arov

a, N

. N.;

Ras

tsve

taev

a, R

. K.;

Ilyuk

hin,

V. V

.; B

elov

, N. V

. Kri

stal

logr

afiy

a 19

79, 2

4N,

1184

-119

2. N

a[In

(H2O

) 6](

SeO

4)2

2503

70

1.63

2 Å

K

rivov

iche

v, S

. V. Z

apis

ki V

sero

ssijs

kogo

Min

eral

ogic

hesk

ogo

Obs

hche

stva

200

6, 8

0-87

. [M

g(H

2O) 4

] 2(S

eO4)

2∙H2O

7100

08

1.63

2 Å

Eu

ler,

H.;

Bar

bier

, B.;

Mee

nts,

A.;

Kirf

el, A

. Z. K

rist

allo

gr. -

New

Cry

stal

Str

uct.

2009

, 224

, 360

-364

. Tl

2[M

g(H

2O) 6

](Se

O4)

2

RA

NY

EK

1.63

2 Å

H

avlic

ek, D

.; Pl

ocek

, J.;

Nem

ec, I

.; G

yepe

s, R

.; M

icka

, Z. J

. Sol

id S

tate

Che

m. 2

000,

150

, 305

. (C

6H16

N2)

SeO

4∙2H

2O

WU

YX

IX

1.63

2 Å

M

arch

ewka

, M. K

.; Ja

ncza

k, J.

; Deb

rus,

S.; B

aran

, J.;

Rat

ajcz

ak, H

. Sol

id S

tate

Sci

. 200

3, 5

, 643

. (C

3H7N

6)4(

SeO

4)2∙3

H2O

8275

7

1.63

3 Å

M

icka

, Z.;

Prok

opov

a, L

.; C

isar

ova,

I.; H

avlic

ek, D

. Col

l. C

zech

. Che

m. C

omm

un. 1

996,

61,

129

5-13

06. R

b 2[M

g(H

2O) 6

](Se

O4)

2

1741

15

1.63

3 Å

Sa

wae

, S.;

Nak

ashi

ma,

T.;

Shig

emat

su, H

.; K

asan

o, H

.; M

ashi

yam

a, H

. J. P

hys.

Soc.

Jpn

. 200

5, 7

4,

2748

-275

3. (

K0.

52R

b 0.4

8)2S

eO4

2406

71

1.63

3 Å

Li

ng, J

.; A

lbre

cht-S

chm

itt, T

. E. I

norg

. Che

m. 2

007,

46,

346

-347

. K

2SeO

4∙2H

IO3

7100

09

1.63

3 Å

Eu

ler,

H.;

Bar

bier

, B.;

Mee

nts,

A.;

Kirf

el, A

. Z. K

rist

allo

gr. -

New

Cry

stal

Str

uct.

2009

, 224

, 360

-364

. Tl

2[C

o(H

2O) 6

](Se

O4)

2

RA

NY

AG

1.

633

Å

Hav

licek

, D.;

Ploc

ek, J

.; N

emec

, I.;

Gye

pes,

R.;

Mic

ka, Z

. J. S

olid

Sta

te C

hem

. 200

0, 1

50, 3

05.

19

(C4H

12N

2)Se

O4∙H

2O

8275

6

1.63

4 Å

M

icka

, Z.;

Prok

opov

a, L

.; C

isar

ova,

I.; H

avlic

ek, D

. Col

l. C

zech

. Che

m. C

omm

un. 1

996,

61,

129

5-13

06. K

2[M

g(H

2O) 6

](Se

O4)

2

1527

20

1.63

4 Å

Li

taie

m, H

.; D

amm

ak, M

.; M

hiri,

T.;

Cou

sson

, A. J

. Allo

ys C

ompd

. 200

5, 3

96, 3

4-39

. (N

H4)

2SeO

4∙Te(

OH

) 6

1584

79

1.63

4 Å

K

rivov

iche

v, S

. V. U

krai

n. D

okl.

Kri

stal

logr

. 200

6, 1

35, 9

6-10

1. [

Al(H

2O) 6

](Se

O4)

(NO

3)∙H

2O

2503

69

1.63

4 Å

K

rivov

iche

v, S

. V. Z

apis

ki V

sero

ssijs

kogo

Min

eral

ogic

hesk

ogo

Obs

hche

stva

200

6, 9

6-10

1.

[Al(H

2O) 6

] 2(S

eO4)

(NO

3)∙H

2O

7100

10

1.63

4 Å

Eu

ler,

H.;

Bar

bier

, B.;

Mee

nts,

A.;

Kirf

el, A

. Z. K

rist

allo

gr. -

New

Cry

stal

Str

uct.

2009

, 224

, 360

-364

. Tl

2[C

u(H

2O) 6

](Se

O4)

2

7100

11

1.63

4 Å

Eu

ler,

H.;

Bar

bier

, B.;

Mee

nts,

A.;

Kirf

el, A

. Z. K

rist

allo

gr. -

New

Cry

stal

Str

uct.

2009

, 224

, 360

-364

. Tl

2[M

n(H

2O) 6

](Se

O4)

2

5107

9

1.63

5 Å

Tr

oyan

ov, S

. I.;

Mor

ozov

, I. V

.; R

ybak

ov, V

. B.;

Stie

we,

A.;

Kem

nitz

, E. J

. Sol

id S

tate

Che

m. 1

998,

14

1, 3

17-3

22.

Cs 4

(SeO

4)(H

SeO

4)2∙

H3P

O4

6723

4

1.63

5 Å

Pi

etra

szko

, A.;

Luka

szew

icz,

K.;

Aug

usty

niak

, M. A

. Act

a C

ryst

allo

gr.,

Sect

. C 1

992,

48,

206

9-20

71.

Li2S

eO4

7178

6

1.63

5 Å

B

aran

, J.;

Lis,

T.; M

arch

ewka

, M.;

Rat

ajcz

ak, H

. J. M

ol. S

truc

t. 19

91, 2

50, 1

3-45

. N

a 4(S

eO4)

(SeO

3)∙H

2O

8275

8

1.63

5 Å

M

icka

, Z.;

Prok

opov

a, L

.; C

isar

ova,

I.; H

avlic

ek, D

. Col

l. C

zech

. Che

m. C

omm

un. 1

996,

61,

129

5-13

06. C

s 2[M

g(H

2O) 6

](Se

O4)

2

8275

9

1.63

5 Å

M

icka

, Z.;

Prok

opov

a, L

.; C

isar

ova,

I.; H

avlic

ek, D

. Col

l. C

zech

. Che

m. C

omm

un. 1

996,

61,

129

5-13

06. (

NH

4)2[

Mg(

H2O

) 6](

SeO

4)2

4097

19

1.63

5 Å

Eu

ler,

H.;

Mee

nts,

A.;

Bar

bier

, B.;

Kirf

el, A

. Z. K

rist

allo

gr. -

New

Cry

st. S

truc

t. 20

03, 2

18, 2

65-2

68.

Rb 2

[Mg(

H2O

) 6](

SeO

4)2

4097

50

1.63

5 Å

Eu

ler,

H.;

Bar

bier

, B.;

Mee

nts,

A.;

Kirf

el, A

. Z. K

rist

allo

gr. -

New

Cry

st. S

truc

t. 20

03, 2

18, 4

05-4

08.

Rb 2

[Zn(

H2O

) 6](

SeO

4)2

20

4110

02

1.63

5 Å

Tr

oyan

ov, S

. I.;

Mor

ozov

, I. V

.; R

ybak

ov, V

. B.;

Kem

nitz

, E. K

rist

allo

graf

iya

2000

, 45,

441

-447

. R

b 2Se

O4∙H

3PO

4

6652

6

1.63

6 Å

Zu

niga

, F. J

.; B

recz

ewsk

i, T.

; Arn

aiz,

A. A

cta

Cry

stal

logr

., Se

ct. C

199

1, 4

7, 6

38-6

40.

Cs 2

SeO

4

4097

22

1.63

6 Å

Eu

ler,

H.;

Mee

nts,

A.;

Bar

bier

, B.;

Kirf

el, A

. Z. K

rist

allo

gr. -

New

Cry

st. S

truc

t. 20

03, 2

18, 2

65-2

68.

Rb 2

[Zn(

H2O

) 6](

SeO

4)2

4097

47

1.63

6 Å

Eu

ler,

H.;

Bar

bier

, B.;

Mee

nts,

A.;

Kirf

el, A

. Z. K

rist

allo

gr. -

New

Cry

st. S

truc

t. 20

03, 2

18, 4

05-4

08.

Rb 2

[Mn(

H2O

) 6](

SeO

4)2

4097

48

1.63

6 Å

Eu

ler,

H.;

Bar

bier

, B.;

Mee

nts,

A.;

Kirf

el, A

. Z. K

rist

allo

gr. -

New

Cry

st. S

truc

t. 20

03, 2

18, 4

05-4

08.

Rb 2

[Co(

H2O

) 6](

SeO

4)2

1712

81

1.63

7 Å

Si

mm

ons,

C. J

.; St

rate

mei

er, H

.; H

itchm

an, M

. A.;

Rile

y, M

. J. I

norg

. Che

m. 2

006,

45,

102

1-10

31.

K2[

Cu(

H2O

) 6](

SeO

4)2

1712

82

1.63

7 Å

Si

mm

ons,

C. J

.; St

rate

mei

er, H

.; H

itchm

an, M

. A.;

Rile

y, M

. J. I

norg

. Che

m. 2

006,

45,

102

1-10

31.

K2[

Cu(

H2O

) 6](

SeO

4)2

2463

02

1.63

7 Å

Pe

rtlik

, F.;

Fuith

, A. H

. Act

a C

ryst

allo

gr.,

Sect

. C 1

989,

45,

158

-159

. Li

2SeO

4

4095

91

1.63

7 Å

Fl

eck,

M.;

Kol

itsch

, U. Z

. Kri

stal

logr

. - N

ew C

ryst.

Str

uct.

2002

, 217

, 15-

16.

Rb 2

[Ni(H

2O) 6

](Se

O4)

2

4095

91

1.63

7 Å

Fl

eck,

M.;

Kol

itsch

, U. Z

. Kri

stal

logr

. - N

ew C

ryst.

Str

uct.

2002

, 217

, 15-

16.

Rb 2

[Cu(

H2O

) 6](

SeO

4)2

4096

69

1.63

7 Å

Eu

ler,

H.;

Mee

nts,

A.;

Bar

bier

, B.;

Kirf

el, A

. Z. K

rist

allo

gr. -

New

Cry

st. S

truc

t. 20

03, 2

18, 9

-10.

[M

n(H

2O) 4

]SeO

4∙H2O

4097

20

1.63

7 Å

Eu

ler,

H.;

Mee

nts,

A.;

Bar

bier

, B.;

Kirf

el, A

. Z. K

rist

allo

gr. -

New

Cry

st. S

truc

t. 20

03, 2

18, 2

65-2

68.

Rb 2

[Co(

H2O

) 6](

SeO

4)2

4097

49

1.63

7 Å

Eu

ler,

H.;

Bar

bier

, B.;

Mee

nts,

A.;

Kirf

el, A

. Z. K

rist

allo

gr. -

New

Cry

st. S

truc

t. 20

03, 2

18, 4

05-4

08.

Rb 2

[Ni(H

2O) 6

](Se

O4)

2

QIX

PES

1.63

7 Å

M

aube

rt, B

. M.;

Nel

son,

J.;

McK

ee, V

.; To

wn,

R. M

.; Pa

l, I.

J.C

hem

.Soc

., D

alto

n Tr

ans.

2001

, 139

5.

(C36

H60

N8)

SeO

4(C

lO4)

4∙H2O

8944

0

1.63

8 Å

Pi

etra

szko

, A.;

Bro

now

ska,

W. S

olid

Sta

te C

omm

un. 1

999,

111

, 205

-209

. R

b 2Li

4(Se

O4)

3∙2H

2O

21

1500

84

1.63

8 Å

W

ildne

r, M

.; St

oilo

va, D

.; G

eorg

iev,

M.;

Kar

adjo

va, V

. J. M

ol. S

truc

t. 20

04, 7

07, 1

23-1

30.

[Be(

H2O

) 4]S

eO4

1507

06

1.63

8 Å

Fu

kam

i, T.

; Che

n R

ueyh

ong

J. P

hys.

Soc.

Jpn

. 200

3, 7

2, 3

299-

3300

. N

a 2Se

O4

1712

80

1.63

8 Å

Si

mm

ons,

C. J

.; St

rate

mei

er, H

.; H

itchm

an, M

. A.;

Rile

y, M

. J. I

norg

. Che

m. 2

006,

45,

102

1-10

31.

K2[

Cu(

H2O

) 6](

SeO

4)2

4096

48

1.63

8 Å

Fl

eck,

M.;

Kol

itsch

, U. Z

. Kri

stal

logr

. - N

ew C

ryst.

Str

uct.

2002

, 217

, 471

-473

. (N

H4)

2[C

o(H

2O) 6

](Se

O4)

2

4097

21

1.63

8 Å

Eu

ler,

H.;

Mee

nts,

A.;

Bar

bier

, B.;

Kirf

el, A

. Z. K

rist

allo

gr. -

New

Cry

st. S

truc

t. 20

03, 2

18, 2

65-2

68.

Rb 2

[Mn(

H2O

) 6](

SeO

4)2

4097

46

1.63

8 Å

Eu

ler,

H.;

Bar

bier

, B.;

Mee

nts,

A.;

Kirf

el, A

. Z. K

rist

allo

gr. -

New

Cry

st. S

truc

t. 20

03, 2

18, 4

05-4

08.

Rb 2

[Mg(

H2O

) 6](

SeO

4)2

4197

76

1.63

8 Å

G

rzec

hnik

, A.;

Bre

czew

ski,

T.; F

riese

, K. J

. Sol

id S

tate

Che

m. 2

008,

181

, 291

4-29

17.

Tl2S

eO4

1545

12

1.63

9 Å

D

amm

ak, M

.; M

hiri,

T.;

Cou

sson

, A. J

. Allo

ys C

ompd

. 200

6, 4

07, 1

76-1

81.

K2S

eO4∙T

e(O

H) 6

2001

56

1.63

9 Å

M

ukht

arov

a, N

. N.;

Ras

tsve

taev

a, R

. K.;

Ilyuk

hin,

V. V

.; B

elov

, N. V

. Dok

l. Ak

ad. N

auk

SSSR

197

7,

235,

575

-577

. N

a[In

(H2O

) 6](

SeO

4)2

2018

93

1.63

9 Å

Y

amad

a, N

.; O

no, Y

.; Ik

eda,

T. J

. Phy

s. So

c. J

pn. 1

984,

53,

256

5-25

74.

K2S

eO4

2807

88

1.63

9 Å

K

olits

ch, U

. Act

a C

ryst

allo

gr.,

Sect

. E 2

002,

58,

3-5

. [M

g(H

2O) 6

]SeO

4

4096

49

1.63

9 Å

Fl

eck,

M.;

Kol

itsch

, U. Z

. Kri

stal

logr

. - N

ew C

ryst.

Str

uct.

2002

, 217

, 471

-473

. (N

H4)

2[Zn

(H2O

) 6](

SeO

4)2

2017

40

1.64

0 Å

M

asch

erpa

-Cor

ral,

D.;

Duc

oura

nt, M

. B.;

Four

cade

, R.;

Mas

cher

pa, G

.; A

lber

ola,

S. J

. Sol

id S

tate

C

hem

. 198

6, 6

3, 5

2-61

. K

2SeO

4∙2Sb

F 3∙H

2O

6092

9

1.64

1 Å

Ta

kaha

shi,

I.; O

node

ra, A

.; Sh

ioza

ki, Y

. Act

a C

ryst

allo

gr.,

Sect

. C 1

987,

43,

179

-182

. R

b 2Se

O4

1712

79

1.64

1 Å

Si

mm

ons,

C. J

.; St

rate

mei

er, H

.; H

itchm

an, M

. A.;

Rile

y, M

. J. I

norg

. Che

m. 2

006,

45,

102

1-10

31.

K2[

Cu(

H2O

) 6](

SeO

4)2

2807

83

1.64

1 Å

K

olits

ch, U

. Act

a C

ryst

allo

gr.,

Sect

. E 2

001,

57,

104

-105

. [C

u(H

2O) 4

]SeO

4∙H2O

22

1634

55

1.64

2 Å

A

mri,

M.;

Zoua

ri, N

.; M

hiri,

T.;

Gra

vere

au, P

. J. A

lloys

Com

pd. 2

009,

477

, 68-

75.

Cs 4

(SeO

4)(H

SeO

4)2)

∙H3A

sO4

2018

82

1.64

2 Å

Y

amad

a, N

.; Ik

eda,

T. J

. Phy

s. So

c. J

pn. 1

984,

53,

255

5-25

64.

K2S

eO4

DEH

QIR

1.

642

Å

Jun-

Jieh

Wan

g; T

essi

er, C

.; H

olm

, R. H

. Ino

rg. C

hem

. 200

6, 4

5, 2

979.

(C

8H20

N) 2

SeO

4∙CH

3CN

838

1.

644

Å

Car

ter,

R.;

Koe

rntg

en, C

.; M

argu

lis, T

. N. A

cta

Cry

stal

logr

., Se

ct. B

197

7, 3

3, 5

92-5

93.

(NH

4)2S

eO4

1546

71

1.64

4 Å

D

amm

ak, M

.; Li

taie

m, H

.; M

hiri,

T. J

. Allo

ys C

ompd

. 200

6, 4

16, 2

28-2

35.

Na 2

SeO

4∙Te(

OH

) 6∙0

.5H

2O

1712

83

1.64

4 Å

Si

mm

ons,

C. J

.; St

rate

mei

er, H

.; H

itchm

an, M

. A.;

Rile

y, M

. J. I

norg

. Che

m. 2

006,

45,

102

1-10

31.

K2[

Cu(

H2O

) 6](

SeO

4)2

DG

LYSE

1.

645

Å

Ole

jnik

, S.;

Luka

szew

icz,

K.;

Lis,

T. A

cta

Cry

stal

logr

., Se

ct. B

197

5, 3

1, 1

785.

(C

2H6N

O2)

2SeO

4

2026

59

1.64

6 Å

M

asch

erpa

-Cor

ral,

D.;

Duc

oura

nt, M

. B.;

Alb

erol

a, S

. J. S

olid

Sta

te C

hem

. 198

8, 7

6, 2

76-2

83.

K2S

eO4∙2

SbF 3

∙0.5

H2O

LATU

MS

1.64

8 Å

K

ono,

Y.;

Take

uchi

, S.;

Yon

ehar

a, H

.; M

arum

o, F

.; Sa

ito, Y

. Act

a C

ryst

allo

gr.,

Sect

. B 1

971,

27,

23

41.

(C10

H12

NO

)SeO

4

1581

6

1.64

9 Å

N

aray

-Sza

bo, I

.; A

rgay

, G. A

cta

Chi

m. A

cad.

Sci

. Hun

g. 1

963,

39,

85-

92.

Na 2

SeO

4

9938

4

1.65

3 Å

Fr

iese

, K.;

Goe

ta, A

. E.;

Leec

h, M

. A.;

How

ard,

J. A

. K.;

Mad

aria

ga, G

.; Pe

rez-

Mat

o, J.

M.;

Bre

czew

ski,

T. J

. Sol

id S

tate

Che

m. 2

004,

177

, 112

7-11

36.

Tl2S

eO4

1604

2

1.65

4 Å

K

alm

an, A

.; C

ruic

ksha

nk, D

. W. J

. Act

a C

ryst

allo

gr.,

Sect

. B 1

970,

26,

436

-436

. N

a 2Se

O4

1606

82

1.67

1 Å

Sm

irnov

, L. S

.; M

elny

k, G

.; Zi

nk, N

.; W

ozni

ak, K

.; D

omin

iak,

P.;

Paw

luko

jc, A

.; Lo

ose,

A.;

Shuv

alov

, L. A

. Pov

erkh

nost

nye

Fizi

ka, K

him

iya,

Mek

hani

ka 2

007,

73-

79.

(NH

4)2(

SeO

4)2

Mea

n 1.

634

Å/9

7

Hyd

roge

nsel

enat

e io

n, H

SeO

4-

SAQ

HO

H

1.58

7+1.

695

Å B

aran

, J.;

Bar

nes,

A. J

.; M

arch

ewka

, M. K

.; Pi

etra

szko

, A. J

.; R

ataj

czak

, H. J

. Mol

. Str

uct.

1997

, 416

, 33

. (C

5H12

NO

2)(H

SeO

4)2(

C5H

11N

O2)

∙H2O

23

1634

55

1.59

6+1.

730

Å A

mri,

M.;

Zoua

ri, N

.; M

hiri,

T.;

Gra

vere

au, P

. J. A

lloys

Com

pd. 2

009,

477

, 68-

75.

Cs 4

(SeO

4)(H

SeO

4)2)

∙H3A

sO4

SUV

QA

B

1.59

7+1.

685

Å S

louf

, M.;

Cis

arov

a, I.

Act

a C

ryst

allo

gr.,

Sect

. C 1

999,

55,

990

0003

. (C

13H

10N

)(H

SeO

4)3∙H

2O

3199

7

1.60

3+1.

714

Å W

asko

wsk

a, A

.; C

zapl

a, Z

. Act

a C

ryst

allo

gr.,

Sect

. B 1

982,

38,

201

7-20

20.

RbD

SeO

4

LEJC

IN

1.60

7+1.

696

Å H

amilt

on, E

. E.;

Fanw

ick,

P. E

.; W

ilker

, J. J

. J. A

m. C

hem

. Soc

. 200

6, 1

28, 3

388.

(C

24H

20P)

3(C

H2O

8Se 2

)(H

SeO

4)

NA

SQIH

1.

608+

1.68

8 Å

Bar

an, J

.; D

rozd

, M.;

Lis,

T.; S

ledz

, M.;

Bar

nes,

A. J

.; R

ataj

czak

, H. J

. Mol

. Str

uct.

1995

, 372

, 29.

(C

5H12

NO

2)(H

SeO

4)2)

∙H2O

5107

9

1.60

9+1.

735

Å T

roya

nov,

S. I

.; M

oroz

ov, I

. V.;

Ryb

akov

, V. B

.; St

iew

e, A

.; K

emni

tz, E

. J. S

olid

Sta

te C

hem

. 199

8,

141,

317

-322

. C

s 4(S

eO4)

(HSe

O4)

2∙H3P

O4

HES

NA

V

1.60

9+1.

716

Å F

leck

, M. A

cta

Cry

stal

logr

., Se

ct. E

200

6, 6

2, o

4939

. C

H6N

3(H

SeO

4)

5108

0

1.61

0+1.

670

Å T

roya

nov,

S. I

.; M

oroz

ov, I

. V.;

Ryb

akov

, V. B

.; St

iew

e, A

.; K

emni

tz, E

. J. S

olid

Sta

te C

hem

. 199

8,

5915

0141

, 317

-322

. C

s 3(H

SeO

4)2(

H2P

O4)

XIN

BEB

1.

610+

1.72

5 Å

Zak

haro

v, M

. A.;

Troy

anov

, S. I

.; R

ybak

ov, V

. B.;

Asl

anov

, L. A

.; K

emni

tz, E

. Kri

stal

logr

afiy

a 20

01,

46, 1

057.

(C

4H12

N)(

HSe

O4)

XIN

BEB

01

1.61

0+1.

725

Å Z

akha

rov,

M. A

.; Tr

oyan

ov, S

. I.;

Ryb

akov

, V. B

.; A

slan

ov, L

. A.;

Kem

nitz

, E. K

rist

allo

graf

iya

2001

, 46

, 105

7. (

C4H

12N

)(H

SeO

4)

3545

6

1.61

1+1.

692

Å B

rach

, I.;

Jone

s, D

. J.;

Roz

iere

, J. J

. Sol

id S

tate

Che

m. 1

983,

48,

401

-406

. R

bHSe

O4

HES

NA

V01

1.

611+

1.71

2 Å

Dro

zd, M

.; B

aran

, J.;

Piet

rasz

ko, A

. Spe

ctro

chim

. Act

a, P

art A

200

5, 6

1, 2

775.

CH

6N3(

HSe

O4)

8508

2

1.61

5+1.

718

Å H

anas

hiro

, K.;

Koy

ano,

N.;

Mac

hida

, M. K

yoto

Dai

gaku

Gen

shir

o Ji

kken

sko

Gak

ujut

su K

oenk

ai

Hob

unsh

u 19

97, 3

1, 1

89-1

92.

KH

SeO

4

8888

3

1.61

5+1.

700

Å T

roya

nov,

S. I

.; M

oroz

ov, I

. V.;

Zakh

arov

, M. A

.; K

emni

tz, E

. Kri

stal

logr

afiy

a 19

99, 4

4, 6

07-6

11.

Cs(

HSe

O4)

∙H2S

eO4

8888

2

1.61

6+1.

719

Å T

roya

nov,

S. I

.; M

oroz

ov, I

. V.;

Zakh

arov

, M. A

.; K

emni

tz, E

. Kri

stal

logr

afiy

a 19

99, 4

4, 6

07-6

11.

K(H

SeO

4)∙H

2SeO

4

24

8889

3

1.61

7+1.

727

Å Z

akha

rov,

M. A

.; Tr

oyan

ov, S

. I.;

Ryb

akov

, V. B

.; A

slan

ov, L

. A.;

Kem

nitz

, E. K

rist

allo

graf

iya

1999

, 44

, 448

-453

. N

aHSe

O4

5108

1

1.61

7+1.

635

Å T

roya

nov,

S. I

.; M

oroz

ov, I

. V.;

Ryb

akov

, V. B

.; St

iew

e, A

.; K

emni

tz, E

. J. S

olid

Sta

te C

hem

. 199

8,

141,

317

-322

. C

s 5(H

SeO

4)3(

H2P

O4)

2

6581

0

1.61

8+1.

715

Å M

akar

ova,

I. P

.; R

ider

, E. E

.; Sa

rin, V

. A.;

Ale

ksan

drov

a, I.

P.;

Sim

onov

, V. I

. Kri

stal

logr

afiy

a 19

89,

34, 8

53-8

61.

RbH

SeO

4

7253

4

1.61

8+1.

715

Å M

akar

ova,

I. P

. Act

a C

ryst

allo

gr.,

Sect

. B 1

993,

49,

11-

18.

RbH

SeO

4

7253

5

1.61

9+1.

693

Å M

akar

ova,

I. P

. Act

a C

ryst

allo

gr.,

Sect

. B 1

993,

49,

11-

18.

NH

4HSe

O4

3000

18

1.62

0+1.

707

Å W

asko

wsk

a, A

.; O

lejn

ik, S

.; Lu

kasz

ewic

z, K

.; C

zapl

a, Z

. Cry

st. S

truc

t. C

omm

un. 1

980,

9, 6

63-6

69.

Rb(

HSe

O4)

3199

8

1.62

1+1.

715

Å W

asko

wsk

a, A

.; C

zapl

a, Z

. Act

a C

ryst

allo

gr.,

Sect

. B 1

982,

38,

201

7-20

20.

(ND

4)D

SeO

4

6580

9

1.62

2+1.

694

Å M

akar

ova,

I. P

.; R

ider

, E. E

.; Sa

rin, V

. A.;

Ale

ksan

drov

a, I.

P.;

Sim

onov

, V. I

. Kri

stal

logr

afiy

a 19

89,

34, 8

53-8

61.

RbH

SeO

4

7119

8

1.62

2+1.

694

Å M

akar

ova,

I. P

.; M

urad

yan,

L. A

.; R

ider

, E. E

.; Sa

rin, V

. A.;

Ale

xand

rova

, I. P

.; Si

mon

ov, V

. I.

Ferr

oele

ctri

cs 1

990,

107

, 281

-286

. R

bHSe

O4

7253

3

1.62

2+1.

694

Å M

akar

ova,

I. P

. Act

a C

ryst

allo

gr.,

Sect

. B 1

993,

49,

11-

18.

RbH

SeO

4

4112

82

1.62

2+1.

723

Å Z

akha

rov,

M. A

.; Tr

oyan

ov, S

. I.;

Kem

nitz

, E. Z

. Kri

stal

logr

. 200

1, 2

16, 1

72-1

75.

Cs(

HSe

O4)

7253

6

1.62

4+1.

690

Å M

akar

ova,

I. P

. Act

a C

ryst

allo

gr.,

Sect

. B 1

993,

49,

11-

18.

NH

4HSe

O4

2079

4

1.62

6+1.

694

Å K

rugl

ik, A

. I.;

Mis

yul',

S. V

.; A

leks

andr

ov, K

. S. D

okl.

Akad

. Nau

k SS

SR 1

980,

255

, 344

-348

. (N

H4)

HSe

O4

2082

9

1.62

6+1.

686

Å A

leks

andr

ov, K

. S.;

Kru

glik

, A. I

.; M

isyu

l', S

. V.;

Sim

onov

, M. A

. Kri

stallo

graf

iya

1980

, 25N

, 114

2-11

47.

(NH

4)H

SeO

4

9451

7

1.62

6+1.

715

Å T

roya

nov,

S. I

.; K

oste

rina,

E. V

.; K

emni

tz, E

. Zh.

Neo

rg. K

him

. 200

1, 4

6, 1

496-

1502

. C

s 4(S

eO4)

(HSe

O4)

2∙HF

2437

1.63

1+1.

712

Å W

asko

wsk

a, A

.; O

lejn

ik, S

.; Lu

kasz

ewic

z, K

.; G

lovy

ak, T

. Act

a C

ryst

allo

gr.,

Sect

. B 1

978,

34,

334

4-

25

3346

. R

bHSe

O4

5915

0

1.63

1+1.

735

Å B

aran

, J.;

Lis,

T. A

cta

Cry

stal

logr

., Se

ct. C

198

6, 4

2, 2

70-2

72. K

HSe

O4

Mea

n

1.61

5+1.

705

Å/3

3 (M

ean

1.63

8 Å

/33)

Sele

nic

acid

, H2S

eO4

8888

3 1.

590+

1.68

7 Å

Tr

oyan

ov, S

. I.;

Mor

ozov

, I. V

.; Za

khar

ov, M

. A.;

Kem

nitz

, E. K

rist

allo

graf

iya

1999

, 44,

607

-611

. C

s(H

SeO

4)∙H

2SeO

4

8888

2 1.

603+

1.68

5 Å

Tr

oyan

ov, S

. I.;

Mor

ozov

, I. V

.; Za

khar

ov, M

. A.;

Kem

nitz

, E. K

rist

allo

graf

iya

1999

, 44,

607

-611

. K

(HSe

O4)

∙H2S

eO4

Mea

n 1.

597+

1.68

6 Å

/2

(Mea

n 1.

642

Å)

Sele

nite

ion,

SeO

32-

VEX

CA

D

1.67

6 Å

W

iech

ocze

k, M

.; Jo

nes,

P. G

. Z. N

atur

fors

ch.,

Teil

B 20

06, 6

1, 1

401.

(C

4H12

N) 2

(SeO

3)

TUY

MO

P 1.

686

Å

Hav

licek

, D.;

Chu

doba

, V.;

Nem

ec, I

.; C

isar

ova,

I.; M

icka

, Z. J

. Mol

. Str

uct.

2002

, 606

, 101

. (C

4H12

N2)

(SeO

3)∙H

2O

YA

SHA

C

1.68

7 Å

To

dd, M

. J.;

Har

rison

, W. T

. A. A

cta

Cry

stal

logr

., Se

ct. E

200

5, 6

1, o

1538

. (C

3H12

N2)

(SeO

3)∙H

2O

BA

YB

UZ

1.68

9 Å

C

hudo

ba, V

.; M

icka

, Z.;

Hav

licek

, D.;

Cis

arov

a, I.

; Nem

ec, I

.; R

obin

son,

W. T

. J. S

olid

Sta

te C

hem

. 20

03, 1

70, 3

90.

(C4H

14N

2)(S

eO3)

∙H2O

4201

79

1.69

1 Å

B

urns

, W. L

.; Ib

ers,

J. A

. J. S

olid

Sta

te C

hem

. 200

9, 1

82, 1

457-

1461

. C

s(U

O2)

(SeO

3)(H

SeO

3)∙3

H2O

BA

YC

EK

1.69

2 Å

C

hudo

ba, V

.; M

icka

, Z.;

Hav

licek

, D.;

Cis

arov

a, I.

; Nem

ec, I

.; R

obin

son,

W. T

. J. S

olid

Sta

te C

hem

. 20

03, 1

70, 3

90.

(C3H

12N

2)(S

eO3)

∙2H

2O

2809

81

1.69

8 Å

W

ickl

eder

, M. S

. Act

a C

ryst

allo

gr.,

Sect

. E 2

002,

58,

103

-104

. N

a 2Se

O3

26

VEX

CEH

1.

698

Å

Wie

choc

zek,

M.;

Jone

s, P.

G. Z

. Nat

urfo

rsch

., Te

il B

2006

, 61,

140

1. (

C4H

12N

) 2(S

eO3)

∙1.5

H2O

BA

YC

IO

1.70

0 Å

C

hudo

ba, V

.; M

icka

, Z.;

Hav

licek

, D.;

Cis

arov

a, I.

; Nem

ec, I

.; R

obin

son,

W. T

. J. S

olid

Sta

te C

hem

. 20

03, 1

70, 3

90.

(C2H

10N

2)(S

eO3)

Mea

n 1.

691

Å/9

Hyd

roge

nsel

enite

ion,

HSe

O3-

ZOK

ZEE

1.64

0+1.

760

Å d

e M

atos

Gom

es, E

.; M

atos

Bej

a, A

.; Pa

ixao

, J. A

.; de

Vei

ga, L

. A.;

Ram

os S

ilva,

M.;

Mar

tin-G

il, J.

; M

artin

-Gil,

F. J

. Z. K

rist

allo

gr. 1

995,

210

, 929

. (C

10H

16N

)(H

SeO

3)∙H

2SeO

3

XU

JDU

B

1.65

2+1.

787

Å L

ukev

ics,

E.; A

rsen

yan,

P.;

Shes

tako

va, I

.; D

omra

chev

a, I.

; Kan

epe,

I.; B

elya

kov,

S.;

Pope

lis, J

.; Pu

dova

, O. A

ppl.

Org

anom

et. C

hem

. 200

2, 1

6, 2

28.

(C6H

16N

O3)

(HSe

O3)

2027

18

1.65

3+1.

801

Å M

icka

, Z.;

Dan

ek, M

.; Lo

ub, J

.; St

rauc

h, B

.; Po

dlah

ova,

J.; H

asek

, J. J

. Sol

id S

tate

Che

m. 1

988,

77,

30

6-31

5. C

s(H

SeO

3)

AD

AV

AC

1.

654+

1.79

1 Å

de

Mat

os G

omes

, E.;

Nog

ueira

, E.;

Fern

ande

s, I.;

Bel

sley

, M.;

Paix

ao, J

. A.;

Mat

os B

eja,

A.;

Ram

os

Silv

a, M

.; M

artin

-Gil,

J.; M

artin

-Gil,

F.;

Man

o, J.

F. A

cta

Cry

stal

logr

., Se

ct. B

200

1, 5

7, 8

28.

(C6H

15N

4O2)

(HSe

O3)

∙0.1

5H2O

7333

2

1.65

7+1.

757

Å L

oub,

J.; M

icka

, Z.;

Podl

ahov

a, J.

; Mal

y, K

.; K

opf,

J. C

oll.

Cze

ch. C

hem

. Com

mun

. 199

2, 5

7, 2

309-

2314

. N

a(H

SeO

4)∙3

H2S

eO3

RES

NEI

1.

657+

1.76

8 Å

Pai

xao,

J. A

.; M

atos

Bej

a, A

.; R

amos

Silv

a, M

.; de

Mat

os G

omes

, E.;

Mar

tin-G

il, J.

; Mar

tin-G

il, F

. J.

Acta

Cry

stal

logr

., Se

ct. C

199

7, 5

3, 1

113.

(C13

H14

N3)

(HSe

O3)

∙H2O

JIV

WEQ

1.

658+

1.78

4 Å

Nem

ec, I

.; C

isar

ova,

I.; M

icka

, Z. J

. Sol

id S

tate

Che

m. 1

998,

140

, 71.

(C

2H6N

O2)

(HSe

O3)

∙C2H

5NO

2

8255

1.65

9+1.

791

Å C

hom

nilp

an, S

.; Li

min

ga, R

. Act

a C

ryst

allo

gr.,

Sect

. B 1

979,

35,

301

1-30

13.

Li(H

SeO

3)

2022

66

1.65

9+1.

783

Å H

iltun

en, L

.; H

olsa

, J.;

Mic

ka, Z

. J. S

olid

Sta

te C

hem

. 198

7, 6

8, 3

07-3

13.

Cs(

HSe

O4)

∙2H

2SeO

3

DEH

QO

X

1.65

9+1.

758

Å J

un-J

ieh

Wan

g; T

essi

er, C

. T.;

Hol

m, R

. H. I

norg

. Che

m. 2

006,

45,

297

9. (

C8H

20N

)(H

SeO

3)

27

XO

RB

UB

1.

659+

1.76

9 Å

Nem

ec, I

. Chu

doba

, V.;

Hav

licek

, D.;

Cis

arov

a, I.

; Mic

ka, Z

. J. S

olid

Sta

te C

hem

. 200

1, 1

61, 3

12.

(C6H

16N

2)(H

SeO

3)2

4030

78

1.66

0+1.

782

Å E

ichh

orn,

K. D

.; K

ek, S

. Z. K

rist

allo

gr. 1

997,

212

, 724

-731

. Li

(HSe

O3)

EKIB

AB

1.

667+

1.76

3 Å

Ritc

hie,

L. K

.; H

arris

on, W

. T. A

. Act

a C

ryst

allo

gr.,

Sect

. E 2

001,

59,

o12

96.

(C2H

7N4O

)(H

SeO

3)

KEL

KA

O

1.66

8+1.

765

Å P

aixa

o, J.

A.;

Silv

a, M

. R.;

Bej

a, A

. M.;

Euse

bio,

E. P

olyh

edro

n 20

06, 2

5, 2

021.

(C

11H

13N

2O2)

(HSe

O3)

2502

86

1.67

0+1.

749

Å K

rivov

iche

v, S

. V.;

Tana

naev

, I. G

.; K

ahle

nber

g, V

.; M

yaso

edov

, B. F

. Dok

l. Ak

ad. N

auk

2005

, 403

, 34

9-35

2. (

(C5H

11)N

H3)

(UO

2)(S

eO4)

(HSe

O3)

6233

5

1.67

1+1.

781

Å B

anno

va, I

. I.;

Vin

ogra

dova

, I. S

.; K

uz'm

in, A

. M.;

Roz

hdes

tven

skay

a, I.

V.;

Uso

v, O

. A.

Kri

stal

logr

afiy

a 19

87, 3

2N, 8

3-85

. R

b(H

SeO

3)

1713

72

1.67

2+1.

761

Å W

eil,

M. A

cta

Cry

stal

logr

., Se

ct. E

200

6, 6

2, i3

8-i4

0. N

H4(

HSe

O3)

6228

9

1.67

6+1.

750

Å R

ider

, E. E

.; Sa

rin, V

. A.;

Byd

anov

, N. N

.; V

inog

rado

va, I

. S. K

rist

allo

graf

iya

1986

, 31N

, 264

-269

. N

a(D

SeO

3)

6228

8

1.67

9+1.

746

Å R

ider

, E. E

.; Sa

rin, V

. A.;

Byd

anov

, N. N

.; V

inog

rado

va, I

. S. K

rist

allo

graf

iya

1986

, 31N

, 264

-269

. N

a(H

SeO

3)

4201

79

1.67

9+1.

767

Å B

urns

, W. L

.; Ib

ers,

J. A

. J. S

olid

Sta

te C

hem

. 200

9, 1

82, 1

457-

1461

. C

s(U

O2)

(SeO

3)(H

SeO

3)∙3

H2O

KEL

KA

O01

1.

679+

1.76

3 Å

Pai

xao,

J. A

.; Si

lva,

M. R

.; B

eja,

A. M

.; Eu

sebi

o, E

. Pol

yhed

ron

2006

, 25,

202

1.

(C11

H13

N2O

2)(H

SeO

3)

Mea

n

1.66

3+1.

770

Å/2

1 (

Mea

n 1.

699

Å)

Sele

nous

aci

d, H

2SeO

3

ZOK

ZEE

1.61

2+1.

739

Å d

e M

atos

Gom

es, E

.; M

atos

Bej

a, A

.; Pa

ixao

, J. A

.; de

Vei

ga, L

. A.;

Ram

os S

ilva,

M.;

Mar

tin-G

il, J.

; M

artin

-Gil,

F. J

. Z. K

rist

allo

gr. 1

995,

210

, 929

. (C

10H

16N

)(H

SeO

3)∙H

2SeO

3

7333

2

1.61

8+1.

735

Å L

oub,

J.; M

icka

, Z.;

Podl

ahov

a, J.

; Mal

y, K

.; K

opf,

J. C

oll.

Cze

ch. C

hem

. Com

mun

. 199

2, 5

7, 2

309-

2314

. N

a(H

SeO

4)∙3

H2S

eO3

28

NIR

SIQ

1.

622+

1.73

5 Å

Pai

xao,

J. A

.; M

atos

Bej

a, A

.; R

amos

Silv

a, M

.; A

lte d

a V

eiga

, L.;

Mar

tin-G

il, J.

; Mar

tin-G

il, F

.; de

M

atos

Gom

es, E

. Z. K

rista

llogr

. - N

ew C

ryst

. Str

uct.

1997

, 212

, 51.

C5H

11N

O2∙H

2SeO

3

2022

66

1.63

2+1.

748

Å H

iltun

en, L

.; H

olsa

, J.;

Mic

ka, Z

. J. S

olid

Sta

te C

hem

. 198

7, 6

8, 3

07-3

13.

Cs(

HSe

O4)

∙2H

2SeO

3

7178

6

1.66

6+1.

740

Å B

aran

, J.;

Lis,

T.; M

arch

ewka

, M.;

Rat

ajcz

ak, H

. J. M

ol. S

truc

t. 19

91, 2

50, 1

3-45

. N

a 2Se

O4∙H

2SeO

3

Mea

n

1.62

1+1.

739

Å/4

(M

ean

1.70

0 Å

)