Organoplatinum Chemistry with a Dicarboxamide–Diphosphine Ligand: Hydrogen Bonding, Cyclometalation, and a Complex with Two Metal–Metal Donor–Acceptor Bonds

The chemistry of the ligand bis­(2-diphenylphosphinoethyl)­phthalamide, dpppa, with platinum­(II) is described. The reaction of dpppa with [Pt2Me4(μ-SMe2)2], 1, in a 2:1 ratio gave a mixture of [PtMe2(dpppa)] and [Pt2Me4(μ-dpppa)2], both of which contain Pt···H–N hydrogen bonds. However, reaction in a 1:1 ratio gave a remarkable tetraplatinum complex, [Pt4Me6(μ-dpppa-H)2], which is shown to contain two Pt–Pt donor–acceptor bonds and in which one arm of the dpppa ligand has been cyclometalated. The reaction of [PtCl2(dpppa)] with silver trifluoroacetate, to abstract chloride, and triethylamine as base has given the bis­(cyclometalated) complex [Pt­(dpppa-2H)], and this has been crystallized in three different forms, in which one or both of the carbonyl groups act as donors to a proton or to silver­(I). The complex [Pt­(dpppa-2H)]·AgO2CCF3·dmso forms a dimer and [Pt­(dpppa-2H)]·(AgO2CCF3)2 forms a coordination polymer in the solid state.