Preparation and characterisation of [PPh4][fac-PtX3(S4N4)](X = Cl, Br or I)

Reaction of [PPh4]X (X = Cl or Br) with K2[PtX4] in water leads to either [PPh4]2[PtCl4] or a mixture of [PPh4]2[PtBr4] and [PPh4]2[Pt2Br6], depending upon the halogen present; reaction of Ptl, with Kl and [PPh4]I leads to [PPh4]2[Pt2I6] as the sole product. All of these compounds react with S4N4 in CH2Cl2 to give the platinum(iv) species [PPh4] [PtX3(S4N4)] which contain the S4N42- ligand. The chloro species may also be obtained by metathesis from K[PtCl3(S4N4)] which is itself prepared by reaction of S4N4 with Zeise's salt, K[PtCl3(C2H4)], in tetrahydrofuran, Comparison of the N15 NMR spectra of labelled complexes with that of [Ir(CO)Cl(S4N4)(PPh3)]-N-15 indicates that in all cases this ligand adopts a facial co-ordination mode, bound by two sulfurs and one nitrogen.Two 2J(N-15-N-15) interactions of magnitude 3 and 5.5 Hz are observed within the ligand.