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

Abstract

[M(η³-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)Ph₂ (where E = O, S or Se) and found that the disulfide reacts cleanly with [PdCl₂(PhCN)₂] in dichloromethane or Na₂[PdCl₄] in ethanol with elimination of HCl to give the unusual neutral N-metallated species [PdCl(Ph₂P(S)NC₆H₄P(S)Ph₂-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)Ph₂-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·0.75CHCl₃, 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.