Synthesis of diphenylantimony(III) dialkyldithio- and diaryldithio-phosphinates and -arsinates; crystal structures of Ph2SbS2MPh2(M = P or As)

Abstract

Diphenylantimony(III) dithiophosphinates and dithioarsinates, Ph₂SbS₂MR₂(M = P, R = Me, Et, Pr, or Ph; M = As, R = Me or Ph), have been synthesised and characterised by their i.r. and ¹H n.m.r. spectra. Structures have been determined for Ph₂SbS₂MPh₂(M = P or As). The compounds crystallise in the triclinic space group P1cmb.macr; (Z= 2), with a= 9.099(3), b= 11.397(3), c= 12.382(4)Å, α= 114.54(2), β= 106.93(2), and γ= 75.41(2)° for M = P and a= 9.1 55(3), b= 11.518(3), c= 12.390(4)Å, α= 115.07(2), β= 106.39(2), and γ= 75.48(2)° for M = As. In each compound there is one short Sb–S contact at 2.490(1)Å for M = P and 2.486(2) for M = As but there are two longer Sb ⋯ S contacts (3.440 and 3.474 Å for M = P and 3.590 and 3.369 Å for M = As). This leads to dimerisation and the formation of eight-membered Sb₂S₄M₂ rings with transannular Sb ⋯ S interactions. Antimony is thus in five-fold, distorted square-pyramidal co-ordination.