The reaction of the tertiary phosphine sulfides R3PS (R = Ph, Me2N or C6H11) with X2 (X2 = I2, Br2, IBr or ICl);: structural characterisation of the CT complexes (Me2N)3PSI2 and Ph3PS(I0.89Br0.11)Br and the ionic compound [{(Me2N)3PS}2S]2+ 2[Br3]-

The reactions of the tertiary phosphine sulfides R3PS (R=Ph, Me2N or C6H11) with X-2 (X=I or Br) and IX (X=Br or Cl) have been studied. Reaction of R3PS with I-2 or IX results in quantitative isolation of the CT complexes R3PSIX (X=I, Br or Cl), except for Ph3PS with I-2 which produces the unusual compound (Ph3PSI2)(2)I-2, which has been crystallographically characterised by earlier workers. The crystal structure of (Me2N)(3)PSI2 has been determined and compared to Ph3PSI2, previously described. The greater d(I-I) for (Me2N)(3)PSI2, 2.856(1) Angstrom, compared to that of 2.823(1) Angstrom for Ph3PSI2 clearly illustrates that d(I-I) in R3PSI2 compounds is sensitive to R, although this effect is less pronounced when compared to that of analogous R3PSeI2 compounds. The crystal structure of the product from the reaction of Ph3PS with IBr has also been determined and represents the first example of a tertiary phosphine sulfide interhalogen CT complex. It has the formula Ph3PS(I0.89Br0.11)Br and is isomorphous with Ph3PSI2. The reaction of R3PS with Br-2 is complex. In the case of Ph3PS, phosphorus-sulfur bond cleavage occurs quantitatively to produce Ph3PBr2 and elemental sulfur. Reaction of (Me2N)(3)PS with Br-2 gives, as one product, [{(Me2N)(3)PS}(2)S][Br-3](2) in moderate (ca. 30%) yield. This unusual dication is compared to the previously reported [((Bu3PTe)-P-t)(2)Te][SbF6](2). Tricyclohexylphosphine sulfide reacts with Br-2 in solvents of low relative permittivity (Et2O) to produce the 1:1 addition complex (C6H11)(3)PSBr2; however, dissolution of this material in solvents of higher relative permittivity results in phosphorus-sulfur bond cleavage to produce (C6H11)(3)PBr2 and elemental sulfur.