Dimethyltellurium(IV) derivatives with mixed 1,1-dithio ligands. Crystal structures of Me 2 Te[S 2 CNMe 2 ][S 2 COEt] and Me 2 Te[S 2 CNEt 2 ][S 2 COMe]

Mixed ligand derivatives of Me 2 TeLL' 2 , where L = N,N-dialkyl dithiocarbamate or O,O-alkylene dithiophosphate and L' = O-alkyl dithiocarbonate, have been synthesized and characterized by elemental analysis, 1 H, 13 C, 31 P, and 125 Te NMR spectroscopy and infrared and Raman spectroscopy, and X-ray crystallography. Me 2 Te[S 2 CNMe 2 ][S 2 COEt], 8: P[Formula: see text] (no. 2), with cell parameters a = 10.073(3) Å, b = 10.139(2) Å, c = 9.108(2) Å, α = 92.36(2)°, β = 115.55(2)°, γ = 111.19(2)°, V = 760.7(4) Å 3 , Z = 2, R = 0.0343, R w = 0.0296. Me 2 Te[S 2 CNEt 2 ][S 2 COMe], 9: P2 1 /c (no. 14) with cell parameters a = 9.881(4) Å, b = 17.671(3) Å, c = 10.149(4) Å, β = 113.65(3)°, V = 1623.3(10) Å 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)° and 162.0(1)° 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) Å, respectively, in 8 and 9. However, only in 9 is there a similar Te—S distance of 3.346(5) Å involving the S 2 COMe group because in 8, the OEt group of S 2 COEt, rather than the terminal S atom, is oriented toward Te. Key words: structure, tellurium, methyl, dithiocarbamates, dithiocarbonates, dithiophosphates.