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The Crystal and Molecular Structure of(//-Oxo)bis{chloro(methyl)thienyI-tellurium(IV)}Raija O ilunkaniem i*3, Risto S. Laitinen3, and M arkku A hlgrénba Department of Chemistry, P. O. Box 3000,

FIN-90014 University of Oulu, Finland b Department of Chemistry, University of Joensuu,

P. O. Box 111, FIN-80101 Joensuu, Finland* Reprint requests to Dr. Raija Oilunkaniemi.

Tel. +368-8-553-1686. Fax. +358-8-553-1608. E-mail: Raija.Oilunkaniemi@oulu.fi

Z. Naturforsch. 56b, 215-217 (2001); received October 26, 2000Methyl Thienyl Telluride, Tellurium(IV)

The formation and the crystal and molecular structure of (//-oxo)bis{chloro(methyl)thienyl- tellurium(IV)}, [Me(Th)TeCl]20 , are described. The compound is orthorhombic, space group Pbcn, a = 1893.30(2), b = 891.96(2), c = 966.24(5) pm; Z - 4. The tellurium atom shows trigonal bi- pyramidal coordination with chlorine and the bridging oxygen atoms in axial, and methyl and thienyl groups in equatorial positions. The two close intermolecular Te(l) —Cl(l) contacts ex­pand the coordination sphere around tellurium to an almost regular octahedron.

The preparation of anhydrides of diaryltellu- rium hydroxide chlorides (R 2TeCl)20 is long- known [1], but structural inform ation is largely lacking. The heating of R 2TeCl(O H ) to 150-180° results in the loss of w ater with the subsequent form ation of (R 2TeCl)20 . In some cases the tre a t­m ent of diaryltellurium dihalogenide with boiling w ater also leads to the anhydride, as does the reac­tion of R 2TeX2 with aqueous base or with aqueous solutions of potassium halides [1].

In this paper we report the form ation of [Me(Th)TeCl]20 (Th = thienyl, C4H 3S) by the re ­action of Me(Th)Te with potassium tetrachlo- roaurate K[AuC14] in ethanol.* The aim of this study was to prepare gold complexes with methyl-

* 0.100 mg (0.27 mmol) K[AuCl4] was dissolved in 15 ml ethanol and an excess of Me(Th)Te was added dropwise into the resulting solution. During the addi­tion a white precipitate was formed. The colour of the precipitate rapidly changed first to grey and then to black.

(thienyl) telluride as part of a systematic investiga­tion of synthesis, structures, and bonding charac­teristics of transition metal complexes with chalcogen containing ligands [2-7]. However, the reaction led to reduction and precipitation of gold that was filtered from the solution. Slow evapora­tion of the filtrate produced colourless plate-like crystals of [M e(Th)TeCl]20 , which were suitable for crystal structure determ ination. There are a few related species for which the X-ray structure is known [8-13].

D iffraction data were collected on a Nonius kappa CCD diffractom eter at 293 K using graphite m onochrom ated M o -K a radiation (A = 0.71073 A ) by recording 360 frames via ^ -ro ta tion (Aq) - 1°; two times 20 s per frame). Crystal data and the details of the structure determ ination are shown in Table 1.** The reflection data were corrected for L orentz and polarization effects and the em ­pirical absorption correction was applied for the net intensities. All structures were solved by direct m ethods using SHELXS-97 [14] and refined using SHELXL-97 [15]. A fter the full-matrix least- squares refinem ent of the non-hydrogen atoms with anisotropic therm al param eters the hydrogen atom s were placed in calculated positions in the thiophene rings (C-H = 93 pm) and in the methyl groups (C-H = 96 pm ). In the final refinem ent the hydrogen atom s were riding with the carbon atom they were bonded to. The isotropic therm al param eters of the hydrogen atom s in the thienyl groups were fixed at 1.2 times and in the methyl groups at 1.5 tim es that of the corresponding car­bon atom . The scattering factors for the neutral atom s were those incorporated with the programs.

The m olecular structure and the num bering of the atom s are shown in Fig. 1 and the selected bond param eters in Table 1. The tellurium atom shows trigonal bipyram idal coordination with chlorine and the bridging oxygen atom s occupying axial positions [the C l(l)-T e (l)-0 (1 ) bond angle is 173.35(11)°]. M ethyl and thienyl groups lie at two of the th ree equatorial positions the third position being occupied by the tellurium lone-pair [C (ll)-

** Crystallographic information (excluding structure factors) has been deposited with the Cambridge Crystallographic Data Centre as supplementary pub­lication no. CCDC 151373. Copies of the data can be obtained free of charge on application to CCDC, 12 Union Road, Cambridge CB2 1EZ, UK (Fax: +44- 1223-336-033; E-mail: deposit@ccdc.cam.ac.uk).

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216 Notizen

Table 1. Details of the structure determination of [Me(Th)TeCl]20.

Crystal dataCompoundRelative molecular mass Crystal system Space group a (pm) b (pm) c (pm)V (pm3)ZF(000)Dc (g cm '3),a(Mo-Ka) (mm-1)0-Range for data collection

Structure determinationCrystal size (mm)Number of reflections collected Number of unique reflections Number of observed reflections Number of parameters/restrainsINT

(all data) 3 wR2 (all data) b Goodness-of-fitMax and min heights in final difference Fourier synthesis (e A -3)

a R} = ZIIF0 I - I F CII/ZIF0 I; b wR2 = [2w (IF0l - IFcl)2/Z w F 02]1/2.

Fig. 1. The molecular structure of [Me(Th)TeCl]20 indi­cating the numbering of the atoms. TTie thermal ellip­soids have been drawn at the 50% probability level. The two halves of the molecule are related by a twofold axis.

Te(l)-C (15) 98.55(19)°]. Consequently, the two equatorial Te-C bonds are quite norm al single bonds with the Te-Calkyl bond [Te(l)-C (15) = 211.2(4) pm] expectedly slightly longer than the Te- Caryi bond [T e (l)-C (ll) = 209.6(4) pm]. The axial T e(l)-C l(l) distance of 271.9(1) pm is longer than that of a standard single bond (the sum of the cova-

Table 2. Selected bond distances (pm) and angles (°) for [Me(Th)TeCl]20.

Bond length Bond angle

T e(l)-0 (1 ) 198.8(2) T e(l)-0(1)-T e(l)# 120.4(2)T e(l)-C l(l) 271.9(1) C l(l)-T e(l)-0(1) 173.35(11)T e(l)-C (ll) 209.6(4) C (ll)-Te(l)-C (15) 98.55(19)Te(l)-C(15) 211.2(4) C (ll)-T e(l)-0 (1 ) 88.44(15)

C(15)-Te(l)-0(1) 89.99(16)C (ll)-T e(l)-C l(l) 88.39(13)C( 15 )-Te-( 1 )-Cl (1) 84.70(14)

lent radii of tellurium and chlorine is 236 pm [16]), as expected for an axial bond in trigonal bipyrami- dal coordination. This is also seen for the Te-Cl bond lengths in TeCl4 as determ ined by electron diffraction [17]. The equatorial bonds show a length of 229.4(5) pm and the axial bonds of 243.5(5) pm. The T e (l)-0 (1 ) bond length of 198.8(2) pm is com ­parable to 198.5(4) and 197.2(3) pm found in (Ph2TeNCS)20 [11] and (Ph2TeN3)20 [8], respec­tively. These values are slightly shorter than what is expected for single bonds (the sum of the covalent radii is 203 pm [16]). W hen com paring these values to the Te-O bond lengths in a -T e 0 2 that also shows trigonal bipyram idal coordination around tellu­rium , it can be seen that the equatorial bonds in the oxide are som ewhat shorter, but the axial bonds are longer (190 and 208 pm, respectively [18]) than in the present com pound and its analogues. The Te-O- Te bond angle in [Me(Th)TeCl]20 is 120.4(2)°. It can be com pared with the Te-O-Te bond angle in (Ph2TeNCS)20 (121.7(4)° [11]} and in (Ph2TeN3)20 {126.2(4)° [8]} as well as in Ph6Te30 2[AC0}2 (ACO= nitrosocarbam yl cyanm ethanide) that contains two oxygen bridges (both ca. 124.2(2)°) [19]. The rela­tively large Te-O-Te angle can either be taken as in­dicative of the 7r-bond character of the Te-O bond, or as the result of the steric effects of the equatorial groups bonded to tellurium.

There are two close interm olecular T e(l) — C l(l) contacts of 333.7(1) and 337.1(1) pm. They expand the coordination sphere around tellurium to an al­m ost regular octahedron and tie the [Me(Th)- TeCl]20 molecules into a continuous three-dim en- sional netw ork (see Fig. 2). This kind of attractive interaction commonly takes place between the lone-pairs of chlorine atom s and positively charged hypervalent tellurium atoms, as exempli­fied by the dim er form ation in [MCl2{TeMe(Th)}2] (M = Pd, Pt) [2],

A possible route of form ation of [Me(Th)- TeCl]20 is illustrated in Scheme 1. It is well-estab­lished that divalent organic tellurides are easily

CioHi2Cl2OS2Te2538.42orthorhombicPbcn1893.30(2) 891.96(2) 966.24(5)

1631.74(9) * 106 410002.1924.1423.29-27.13

0.25 * 0.15 * 0.10 24179 1808 1636 80/0 0.0535 0.0435 0.0612 1.2570.467 -0.714

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Fig. 2. Intermolecular tellurium-chlorine interactions in [Me(Th)TeCl]20.

chlorinated {see for instance the preparation of [(M e3Si)2N]2TeCl2 from [(M e3Si)2N]2Te and S 0 2C12 [20]}. Potassium tetrachloroaurate is likely to act as an oxidizing and chlorinating agent with sim ultaneous form ation of metallic gold and po­tassium chloride. M e(Th)TeCl2 thus form ed is then converted into M e(Th)Te(O H )Cl and finally to the end product [M e(Th)TeCl]20 in the aqueous ethanol solution containing potassium chloride. This schem e is consistent with that presented by L ederer alm ost one hundred years ago [1].

A cknow ledgem entsFinancial support from Academy of Finland is

gratefully acknowledged.

Me

T h 'Te

K |A uC l4]/EtOH

-KC1, -Au

M e

T h'

Cl

Cl

-H ,0

M e......

T h " "

Cl

-T e

O ------T e------ Cl

M e Th

Scheme 1.

[1] K. J. Irgolic, The Organic Chemistry of Tellurium, Gordon and Breach Science Publishers, New York, 1974. p. 187, and references therein.

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[6] M. S. Hannu, R. Oilunkaniemi, R. S. Laitinen, M. Ahlgren, Inorg. Chem. Commun. 3, 397 (2000).

[7] R. Oilunkaniemi, R. S. Laitinen, M. Ahlgren, Inorg. Chem. Commun. 3, 8 (2000).

[8] P. Magnus, M. B. Roe, V. Lynch, C. Hulme, J. Chem. Soc., Chem. Commun. 1609 (1995).

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[10] N. W. Alcock, W. D. Harrison, C. Howes, J. Chem. Soc., Dalton Trans. 1709 (1984).

[11] C. S. Mancinelli, D. D. Titus, R. F. Ziolo, J. Organo­met. Chem. 140, 113 (1977).

[12] M. M. Mangion, M. R. Smith, E. A. Meyers, J. Het- erocycl. Chem. 10, 543 (1973).

[13] J. H. Drake, M. B. Hursthouse, M. Kulcsar, M. E. Light, A. Silvestru, Program and Abstracts, The Ninth International Conference on Inorganic Ring Systems, Saarbrücken 23.-28.7.2000, P-129.

[14] G. M. Sheldrick, SHELXS-97. Program for Crystal Structure Solution, University of Göttingen (1997).

[15] G. M. Sheldrick, SHELXL-97. Program for Crystal Structure Refinement, University of Göttingen(1997).

[16] J. Emsley, The Elements, 3rd Ed., Clarendon Press, Oxford (1998).

[17] A. Koväcs, K.-G. Martinsen, R. J. Konings, J. Chem. Soc., Dalton Trans. 1037 (1997).

[18] O. Lindqvist, O., Acta Chem. Scand. 22, 977 (1968).[19] K. V. Domasevitch, V. V. Skopenko, E. B. Rusanov,

Z. Naturforsch. 51b, 832 (1996).[20] J. Pietikäinen, R. S. Laitinen, J. Valkonen, Acta

Chem. Scand. 53, 963 (1999).

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