516 [PhCHENMea] 2+ .[Pd(B,oH,2)2] 2_2CHaCN ligand in the present compound are as follows: B(c)--B(d) 1.8249 (19), B(h)--B(/) 1.9837 (19), B(a)--.B(b) 3.352 (2) /~; height of Pd above the B(a)B(h)B(i)B(b) plane 0.5693 (22) A. We thank the SERC for support (SAM), and the Callery Chemical Company for a generous gift of decaborane. References BRILL, R., DmTmCn, H. & Dw_a~KS,H. (1971). Acta Cryst. B27, 2003-2018. FmTCmE, C. J. (1967). lnorg. Chem. 6, 1199-1203. GouLo, R. O. & Smaaa, D. E. (1986). CADABS. Program for data reduction. Univ. of Edinburgh, Scotland. GOULD, R. O. & TAYLOR,P. (1986). CALC. Program for molecu- lar geometry calculations. Univ. of Edinburgh, Scotland. GUGGENBERGER,L. J. (1972). J. Am. Chem. Soc. 94, 114-119. KLANBERG, F., WEGNER, P. A., PARSHALL, G. W. & MUETT-ERTIES, E. L. (1968). Inorg. Chem. 7, 2072-2077. MACGREGOR, S. A., YELLOWLEES,L. J. & WELCH, A. J. (1990a). Acta Cryst. C46, 551-554. MACGREGOR, S. A., YELLOWLEES, L. J. & WELCH, A. J. (1990b). Acta Cryst. C46, 1399-1402. MALLINSON,P. & MUIR, K. W. (1985). J. Appl. Cryst. 18, 51-53. SrmLDRICK, G. M. (1976). SHELX76. Program for crystal struc- ture determination. Univ. of Cambridge, England. WALKER, N. G. & STUART,D. (1983). Acta Cryst. A39, 158-166. WYNI), A. J., MACGREGOR, S. A., GOULD, R. O., TAYLOR, P., YELLOWLEES,L. J. & WELCH, A. J. (1990). Work in progress. WYND, A. J. & WELCH, A. J. (1987). J. Chem. Soc. Chem. Commun. pp. 1174-1176. WYND, A. J., WELCH, A. J. & PARISH, R. V. (1990). J. Chem. Soc. Dalton Trans. pp. 2185-2193. Acta Cryst. (1991). C47, 516-519 Structure of Di-#-bromo-(tetrabromo-lK4Br)bis(N,N-dimethylselenourea-2~Se) - ditellurium(ll,lV)--Acetonitrile--Methanol (2/3/1) BY H. M. K. K. PAa~mRANA, J. H. REIBENSPIES, E. A. MEYERS* AND R. A. ZINGARO Department of Chemistry, Texas A & M University, College Station, TX 77843, USA (Received 30 April 1990; accepted 28 August 1990) Abstract. 2[TeEBr6(C3HsNESe)E].3CEH3N.CH3OH, M,=2228.7, monoclinic, P21, a=9.973 (3), b = 16.659 (6), c= 16-930 (6) A, fl = 101-03 °, V = 2760.8 (16)/~3, Z = 2, Dx = 2.681 Mg m -3, Mo Kt~, A = 0.71073 A,/z = 13.11 mm -1, F(000) = 2016, T = 193 K, R = 0-053 for 3379 reflections and 305 param- eters. The structure consists of two crystallo- graphically distinct units. In each of them, a Te TM species has a sixfold, nearly octahedral configuration of Br atoms around it. Two of these Br atoms are shared (cis) with a TeII atom to which are also attached two molecules of N,N-dimethylselenourea, producing a distorted square-planar configuration of ligands around Te n. The two crystallographically distinct units are similar, but one of them is coordi- nated by two CH3CN moieties and the other by one CH3CN and one CH3OH moiety. Introduction. During the preparation of thin films of Te-Se alloys, a number of products of the reactions between Te TM halides and substituted selenoureas have been isolated. One of these, the title compound, is unusual in that both Te TM and Te n are present in the same molecule and share two Br atoms. There * To whom inquiries should be directed. 0108-2701/91/030516-04503.00 appear to be no previously reported cases of such structures involving tellurium, although the com- pound [(C2Hs)EN]2Se2Br8 contains an anion with Se n and Se TM sharing two Br atoms, which is remarkably similar to the uncharged species found here (Hauge, Maroy & Odegard, 1988). The purpose of the present study is to compare the structure of this mixed valence compound with those that contain TeII and Te TM in more conventional materials and also to compare the structure with that of the anala- gous selenium compound mentioned above. Experimental. When TeBr4 was reacted with N,N- dimethylselenourea (DMSeU) in C2HsOH, an insol- uble product was formed. After separating the solid, refluxing in CH3OH and filtering, a few orange crystals of the title compound grew from solution upon standing. A single crystal was selected, attached with Dow stopcock grease to a glass fiber, mounted on a Nicolet R3m/V diffractometer and cooled to T = 193 K with a stream of N2 gas. Unit- cell dimensions were obtained from measurements of 20 for 25 reflections, 8 _< 20 _< 30 °, using graphite- monochromatized Mo Ka radiation. Intensities were measured for reflections in the range 4.0 _< 20 _< 50 °, -ll_<h_<9, -19_<k_<0, -20_<l<__0, using a © 1991 International Union of Crystallography