The preparation and structure of [Pt(S2N2){P(OR)(n)R '(3-n)}(2)] and [Pt(SeSN2){P(OMe)(n)Ph3-n}(2)] (n=0-3)

Dissolution of [S4N3]Cl in liquid ammonia produces a reactive solution which on treatment with cis [PtCl2(PR3)(2)] gives [S2N2](2-) complexes in 32-76% yields. Similarly, SeCl4 and [S4N3]Cl in a ratio of 5:1 react cleanly with cis-[PtCl2{P(OMe)(n)-Ph3-n}] to give the desired selenosulfur dinitrido, [SeSN2](2-) complexes with no phosphorus containing starting material evident by P-31 NMR spectroscopy. The new complexes were characterised by IR, P-31 NMR, microanalysis and X-ray crystallography with nine crystal structures being reported. In P-31 nmr the (1)J PtP coupling constants are influenced by the oxygen content of their phosphorus ligands. In the mixed chalcogen complexes the Pt-N bond lengths appear to follow a simple trend as a consequence of the electronic properties of the phosphorus ligand and these trends can be interpreted empirically by examination of the LUMO but are not well supported by DFT calculations.