Synthesis of chelate complexes and the dichalcogen derivatives of the unsymmetrical diphosphine ligand Ph₂PNHC₆H₄PPh₂. Molecular Structure of [PtCl₂(Ph₂PNHC₆H₄PPh₂)]·0.75dmso·0.75CHCl₃

[M(eta (3)-C3H5)(L)][Cl] (M=Pt or Pd and L=Ph2PNHC6H4PPh2), [MX2(L)] (where M=Pt, X=Me, Cl, Br or I and where M=Pd or Ni X=Cl), [PtMeCl(L)], [Mo(CO)(4)(L)] and [(AuCl)(2)(L)] have been synthesised. In all complexes except [(AuCl)(2)(Ph2PNHC6H4PPh2)] where the diphosphine acts as a bridging ligand between the two metal centres a chelating coordination mode is observed. We have also prepared and characterised the dichalcogen compounds Ph2P(E)NHC6H4P(E)Ph-2 (where E=O, S or Se) and found that the disulfide reacts cleanly with [PdCl2(PhCN)(2)] in dichloromethane or Na-2[PdCl4] in ethanol with elimination of HCl to give the unusual neutral N-metallated species [PdCl(Ph2P(S)NC6H4P(S)Ph-2-S,N,S)], which contains both S-P-C-C-N-Pd six and N-P-S-Pd four-membered metallacycles. The cationic species [Pd(PPh3)(Ph2P(S)NC6H4P(S)Ph-2-S,N,S)][ClO4] was generated by the sequential addition of first Ag[ClO4] followed by PPh3 to the neutral chloride. The molecular structure of [PtCl2(Ph2PNHC6H4PPh2)].0.75dmso .0.75CHCl(3), which reveals a puckered ring and displays hydrogen-bonding interactions between the ligand amine proton and the oxygen atom of the dmso molecule, has been determined by single crystal X-ray diffraction.