Synthesis, spectroscopic, and structural studies of dimethyltellurium(IV) alkylene and diphenyl dithiophosphates. Crystal structures of and

Dimethyltellurium alkylene dithiophosphates of the type where G = CMe 2 CMe 2 , CHMeCHMe, CH 2 CMe 2 CH 2 , and CH 2 CEt 2 CH 2 , have been synthesized in 80-90% yields by reaction of the corresponding sodium or ammonium salts of the appropriate dithiophosphoric acids with dimethyltellurium dichloride in toluene. Me 2 Te[S 2 P(OPh) 2 ] 2 was also prepared in a similar fashion. The compounds have been characterised by elemental analyses and 1 H, 13 C, 31 P, and 125 Te NMR, infrared and Raman spectroscopy. The crystal structures of and were determined. 1 , crystallizes in space group P2 1 /c (No. 14) with the cell parameters a = 12.707(3) Å, b = 11.482(2) Å, c = 16.782(2) Å, β = 98.00(1)°, V = 2424(1) Å 3 , Z = 4, R = 0.0399, R w = 0.0343. 4 , crystallizes in space group (No. 2) with the cell parameters a = 12.580(3) Å, b = 13.313(3) Å, c = 8.206(1) Å, α = 91.28(2)°, β = 104.94(2)°, γ = 78.52(2)°, V = 1301(1) Å 3 , Z = 2, R = 0.0364, R w = 0.0295. The immediate environment about tellurium in both molecules is that of the saw-horse structure typical of tellurium(IV) compounds with the two methyl groups equatorial and one sulfur atom from each dithiophosphate group occupying the axial positions. The consideration of the second sulfur atom as part of the coordinating sphere is discussed in terms of a modification of Pauling's approach to partial bond orders. The 1 H NMR spectra suggest that these dithiophosphates may be fluxional in solution and/or that there is rapid exchange of the sulfur atoms.