SULFUR-CARBON BOND-CLEAVAGE IN REACTIONS OF RHENIUM(V) COMPLEXES OF NS3 LIGANDS WITH TERTIARY PHOSPHINES - CRYSTAL AND MOLECULAR-STRUCTURESOF [REO(SCH2CH2NCOCH2S)(PME2PH)] AND [REO(SCME2CH2NCOCH2SCH2CH2S)(PMEPH2)]

The neutral rhenium(v) oxo complex [ReO{S(CH2)(2)SCH2CONCH2S}] reacted with tertiary phosphines PMe2Ph or PMePh2 to give the rhenium(v) spec ies [ReO(NS2)(PR'(3))] (PR'(3) = PMe2Ph 1, or PMePh2 2), with loss of a SCH2CH2 group. The introduction of dimethyl substituents at C(6) of the tetradentate ligand prevents C-S bond cleavage and [ReO(NS2)(PR'(3 ))] type complexes were formed (PR'(3) = PMe2Ph 3, or PMePh2 4). The c rystal and molecular structures of complexes 1 and 4 have been determi ned. Complex 1 is essentially square pyramidal with an apical oxo grou p and a PNS, donor set in the basal sites. The geometry of 4 is essent ially octahedral with a thiolate sulfur of the NS3 ligand trans to the oxo group.