INDIAN J. CHEM., VOL. 20A, JANUARY 1981

""-oeMJ:l[

The electronic spectra recorded in chloroformand acetone show a single band in the region 24528-24380 cm". Absence of d-d transitions rules outthe presence of any unpaired electron in the titaniumion'",

On the basis of elemental analysis, electricalconductance, electronic and infrared spectral studiesthe structures III, IV and V may be assigned to thecomplexes of the type Cp2T(OCM)Cl, Cp2Ti(OCM)2and CP2(02CM), respectively.In all these complexes the Cp groups occupy cornersof a tetrahedron which accords with the literaturefindings~11-23.

Two of the authors (RS and GG) thank the CSIR,New Delhi for the award of Junior Research Fellow-ships.

References1. BRAT,A. N. & JAIN,B. D., Proc. Indian Acad. sa., 53 (1961),

147.2. JAIN, B. D. & SINGH,H. B., Indian J. Chem., 2 (1964), 246.3. RASTOGI,D. K., SRIVASTAVA,A. K. & AGGARWAL,B. R.,

Indian J. Chem., 7 (1969), 732.4. JAIN, B. D. & SINGH, H. B., J. less-common Metals, 7

(1964), 464.5. JAIN, B. D. & SINGH, H. B., Indian J. Chem., 1 (1963), 317.6. JAIN, B. D. & KUMAR, R., Proc. Indian Acad. Sci., 60A

(1964), 265.7. PATROVSKY,V., Colin Czech. Chem. Commun., 27 (1962),

1824.8. ELSCH, J. J. & KING, R. B., Organomet. Synth., Vol. 1

(Academic Press, N.Y.), 1965.9. WILKINSON,G., Corrox, F. A. & BIRMINGHAM,J. M., J,

inorg: nucl. Chem., 2 (1966), 95.10. PECHMANN,H. Von., Ber dt chem. Ges., 17 (1884), 929.11. SHAH, N. M. & MEHTA, D. H., J. Indian chem. Soc., 31

(1954), 784.12. JAIN, B. D. & SINGH,H. B., Indian J. Chem., 1 (1963),369.13. RAMASWAMY,K. K., JOSE, C. 1. & SEN, D. N., Indian J.

Chem., 5 (1967), 156.14. RAMSHARAN,GUPTA,G. & KApOOR,R. N., J. less-common

Metals, 60 (1978), 171.15. PRABHAKARAN,C. P. & PATIL,C. C., J. inorg. nucl. Chem.,

31 (1969), 3316.16. ROSHCHUPKINA,O. S., DUBOVITSKII,V. A. & BOROD'KO,

Yu. G., zt; strukt, Khim., 12 (1971), 1007.17. FRITZ, H. P., Advan. organometal. Chem., 1 (1960), 262.18. BRAININE,E. M., MINACHEVA,M. Kh. & LIKSHINI,B. V.,

Izv. Akad. Nauk SSSR, Ser. Khim., (1968),817.19. MASLOWSKY,Jr., E. & NAKAMOTO,K., Appl. Spectrosc.,

25 (1971), 187.20. CHIEN, J. C. W., J. phys. Chem., 67 (1963), 2477.21. KING, R. B., J. Am. chem. Soc., 91 (1969), 721.22. GIDDINGS,S. A. & BEST,R. J., J. Am. chem. Soc., 83 (1961),

2393.23. ALEKSCEV,N. V. & RONOVA,I. A., Zh. strukt. Khim., 7

(1966), 103.

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{

Preparation & Characterization of La2 TiMn06

K. V. RAMANUJACHARY& C. S. SWAMY*Department of Chemistry, Indian Institute of Technology,

Madras 600 036

Received 16 January 1980; revised and accepted 5 April 1980

.•.•. The compound LazTiMnO. has been prepared by solid statereaction of the component ions in suitable form. X-ray analysisshows it to be orthorhombic and the cell constants are a =5.506 A, b = 5.950A and c = 7.636 A. It is found to be essential-ly a p-type semiconductor with ex = 150!l.V K-l. Weiss constanthas a value -88 K and it shows IR bands at 400-450 and. 575-600 cm-1 characteristic of Va and v, modes of the Ti'+ O. octa-hedra.

MULTIPLE ion substituted perovskites of thetype A2BB06 with transition metal ions at

B site, are found to have interesting solid state anduseful catalytic properties. Perovskites having theformulae La2TiMOs (M=Cu, Ni, Zn and Co) withthe divalent transition metals occupying octahedralsites have been prepared and characterized byRamadas et al), The catalytic activity of the firstthree compounds of the above series towards N20decomposition has been determined+". As a part ofa detailed study on the series La2TiMn06, we reportin this communication the preparation and charac-terization of the compound La2 TiMn06•

Lanthanum oxide (99.99 % pure, Indian RareEarths Limited), titanium dioxide (M & B chemicals)and manganese oxalate were used for preparing thecompound. X-ray powder diffraction was obtainedusing CuKex.radiation in a Philips diffractometer unit.Thermogravimetric analysis was carried out in aStanton thermobalance upto 1273 K. Electricalconductivity was determined in a conventional two-probe cell, by applying known amount of constantvoltage across the pellatized sample and measuringthe current at various temperatures using Hewlett-Packard microvolt ammeter. Seebeck potentialswere determined in a conventional Seebeck coefficientmeasurement apparatus described elsewhere+ Mag-netic susceptibility was determined employing aCahn RG electromicrobalance to measure theweight changes and a Brucker magnet to vary thefield. Infrared spectra was recorded in 100-500 cm-1and 400-800 em"! regions using Poly tech Far IR-30and Beckman IR-12 spectrometers respectively.Chemical analysis of the sample established the oxi-dation state of the manganese to be +2.

The compound La2TiMn06 was prepared asfollows: Stoichiometric amounts of La203, TiOaand manganese oxalate were thoroughly mixed andfired at 1223 K for 16 hr. The resulting intermediatecomposition on reduction in an atmosphere ofhydrogen at 1173 K for 24 hr, yielded the finalproduct.

Various interplanar distances and correspond-ing hkl values obtained by the analysis of the X-raydiffractogram are listed in Table 1. This data hasbeen successfully indexed on the basis of orthorhom-

\

TABLE 1 - X-RAy ANALYSIS DATA FOR THE CoMPOUNDLa.TiMn06t

hkl IntensityCalcObs

3.9753.5473.1732..8082.6742.3062.2841.7801.7511.6281.6191.4091'268

3.8173.571

2.7752.6172.346

1.7821.7531.6091.6061.4111.265

00211l

112120022

213310230024141412

mWvwvsvwm

wmwmww

ta = 5.506 A; b = 5.950 A; c = 7.636 A.

bic unit cell and the cell parameters were refinedusing a standard computer programme and the valuesare also reported in Table 1. When the X-ray ana-lysis of the compound was carried out before thereduction in hydrogen atmosphere few extra lines,'characteristic of LalP3' albeit weak at d=2.985,2.265 and 1.966 A were observed. These lines werenot found after re-heating in hydrogen atmosphereindicating the formation of single phase. The extralines in the intermediate composition may be due tothe presence of various oxidation states of manganese,which favour the separation of LaP3 phase. Thistype of binary phase formation has been observedby Ramadas et aU while preparing the compoundLazTiCo06, wherein Co exists in +2 and +3 states.

Thermogravimetric analysis of the compoundshowed a gain in mass starting from 633 K onwards.This could be due to the uptake of oxygen, leadingto the formation of higher valent manganese ions.X-ray analysis of the compound obtained after TGanalysis revealed the presence of separate La203phase. This could be due to the re-oxidation of thecompound LazTiMn06•

The Seebeck potential measurements showed thatLa2TiMnOGisessentiallyp-type with 1X=150",VK-l.Activation energy for electrical conduction obtainedfrom the log <1 versus liT plot was found to be0.69 eV. Interestingly this compound did not showany polarization unlike the other compounds of thesame series'.

The plot of l/XM versus T (XM is molar magneticsusceptibility) was linear starting from 77 K onwards.As the values of magnetic susceptibility could not beobtained below 77 K (liquid N, temp.) it was difficultto confirm whether the compound was antiferro-magnetic or ferrimagnetic The Weiss constant wasevaluated to be -88 K.

The IR spectrum showed two strong broad peaks,one centered at 400-450 and other at 575-600 cm".According to Blasse et al.5,6 these peaks can beattributed to the \13 and \14 modes of TiH06 octa-hedra as this acts as a highly charged ion octahedra.This is further supported by the fact that these twobands occur-v at the same position in all La2 TiM06,

,.

/

(

irrespective of the identity of M ion. The bandsare broad and this may be ascribed to various factorslike incomplete ordering of Mn2+ and TiH ionslowering of crystal symmetry and lowering of sit~symmetry, at the cation.

Financial support from Indian Institute of Tech-nology, Madras for one of us (K.V.R) is gratefully

. - acknowledged.

References1. RAMADAS, N., GOPALAKRISHNAN, J. & SASTRY, M. V. C.,

J. inorg. nucl. Chem., 40 (1978), 1453.2. VINOD RAM SASTRI, PITCHAI, R. & SWAMY, c. S., Curro

Sci., 48 (1979), 10.3. SASTRI, V. RAM, PITCHAI, R. & SWAMY, C. S., Indian J.

Chem., 18A (1979), 213.4. NARAMSIMHAN, C. S., Ph. D. Thesis, IlT Madras (1977).5. BLASSE, G. & CORSMIT, A. F., J. Solid State Chern. 6

(1973), 513. '6. CORSMIT, A. F., HOEFDRAAD, H. E. & BLASSE, G., J.

inorg. nucl. Chem., 34 (1972), 3401.

Unsymmetrical Chelate Complexes of CobaIt(UI):Isomeric Forms of cis-Hydroxoaquoglycinatobiguani-decobaIt(IU) & cis-(~)-Dichloroglycinatobiguanideco-

baIt(UI) Complexes

B. CHAKRAVARTY·, S. MODAK & P. K. DASDepartment of Chemistry, University of Kalyani,

Kalyani 741 235

Received 27 March 1980; accepted 15 May 1980

A few cis-disubstituted glycinatobiguanide complexes ofcobalt(ID) have been isolated in the solid state. Because of thepresence of an unsymmetrical ligand (glycinate ion), the cis-isomer itself exists in two isomeric 0(- and fl- forms, whichhave been separated and characterised.

In this note we describe the isolation and charac-terization of a few cis(IX-) and cis(f3-) complexes of

cobalt(III) with the unsymmetrical glycinato ligand.The corresponding trans-complexes could not beisolated.

The starting complex, glycinatobisbiguanideco-balt(III) perchlorate was obtained by the metathesisof the corresponding sulphate, prepared accordingto literature', with barium perchlorate in aqueoussolution.

cis(IX-)and cis (f3- )-Hydroxoaquoglycinatobiguani-decobalt(/II) perchlorates as violet and reddish pinkcomplexes respectively ~ These were obtained by thetreatment of glycinatobisbiguanidecoba1t(III) perchlo-rate with a dilute solution of perchloric acid (0.5 M)on a water bath. When the whole solution turneddeep purple, it was just neutralized with potassiumbicarbonate (the colour changed from purple to violetat this stage) and cooled. The violet colouredsolution was separated from solid potassium per-chlorate by decantation and passed through a silicacolumn. The complex species adsorbed only froma neutral solution, since in acidic or in basic medium,all the complex species passed through the column.When the adsorbtion was complete, the column waseluted with a dilute (pH,.... 5.0) acidic solution. The

97