Stepwise sulfuration of the terminal phosphido complex trans-[PtCl(PHCy2)2(PCy2)]:: Synthesis of [Pt(κ2S,S′-PS2Cy2)(PHCy2)2]Cl and [Pt(κ2S,S′-PS2Cy2){κP-P(S)Cy2}(PHCy2)] and crystal structure of [Pt(κ2-S,S-PCy2S2)(κ-S-PCy2S2)(PHCy2)]

The terminal phosphido complex trans-[PtCl(PHCY2)(2)(PCY2)] (1) has been prepared, exploiting the reversibility of the reaction with HCl, by action of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) on [PtCl(PHCY2)(3)]Cl, and its reactivity towards elemental sulfur studied. The first product obtained by reaction of 1 with 1 equiv. of sulfur is trans- [PtCl(PHCy2)(2){kappa P-P(S)-Cy-2}] (2), which rapidly isomerises in halogenated solvents into cis-[PtCl(PHCy2)(2){kappa P-P(S)Cy-2}] (3). Further addition of sulfur causes the formation of a mixture of [pt(kappa S-2, S'-PS2Cy2)-(PHCy2)(2)]Cl (4) and [Pt(kappa S-2,S'-PS2Cy2) {kappa P-P(S)Cy-2) (PHCy2)] (5), which could be selectively synthesised; the first upon sulfuration. of pure 3 and the second by reaction of 4 with 1 equiv. of sulfur in the presence of DBU. Complex 5 can be further sulfurated to [Pt(kappa S-2,S'-PCy2S2) (kappa S-PCy2S2) (PHCy2)] (6), which is fluxional in solution and was also characterised by single-crystal X-ray diffraction.