Dimethyltellurium(IV) derivatives with mixed 1,1-dithio ligands.: Crystal structures of Me2Te[S2CNMe2][S2COEt] and Me2Te[S2CNEt2][S2COMe]

Mixed ligand derivatives of Me2TeLL2', where L = N,N-dialkyl dithiocarbamate or O,O-alkylene dithiophosphate and L' = O-alkyl dithiocarbonate, have been synthesized and characterized by elemental analysis, H-1, C-13, P-31 and Te-125 NMR spectroscopy and infrared and Raman spectroscopy, and X-ray crystallography. Me2Te[S2CNMe2][S2COEt], 8: P (1) over bar (no. 2), with cell parameters a = 10.073(3) Angstrom, b = 10.139(2) Angstrom, c = 9.108(2) Angstrom, alpha = 92.36(2)degrees, beta = 115.55(2)degrees, gamma = 111.19(2)degrees, V = 760.7(4) Angstrom(3), Z = 2, R = 0.0343, R-w = 0.0296. Me2Te[S2CNEt2][S2COMe], 9: P2(1)/c (no. 14) with cell parameters a = 9.881(4) Angstrom, b = 17.671(3) Angstrom, c = 10.149(4) Angstrom, beta = 113.65(3)degrees, V= 1623.3(10) Angstrom(3), Z = 4, R = 0.0567, R-w = 0.0514. The immediate environment about tellurium in both molecules is essentially that of a saw-horse structure in which the lone pair is apparently stereochemically active and occupying an equatorial position in a distorted trigonal bipyramid. The S-Te-S angles in the two molecules are 166.87(6)degrees and 162.0(1)degrees for 8 and 9, respectively. In both molecules, the Te-S bonds to the dithiocarbamate groups are slightly shorter than those to dithiocarbonates. The dithiocarbamate groups are oriented to give secondary interactions involving the apparently terminal sulfur atoms resulting in Te-S distances of 3.205(2) and 3.277(4) Angstrom, respectively, in 8 and 9. However, only in 9 is there a similar Te-S distance of 3.346(5) Angstrom involving the S2COMe group because in 8, the Oft group of S2COEt, rather than the terminal 8 atom, is oriented toward Te.