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 I [Pt2Me4(mu-SMe2)(2)], 1, in a 2:1 ratio gave a mixture of [PtMe2(dpppa)] and [Pt2Me4(mu-dpppa)(2)], both of which contain Pt center dot center dot center dot H-N hydrogen bonds. However, reaction in a 1:1 ratio gave a remarkable tetraplatinum complex, [Pt4Me6(mu-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)]center dot AgO2CCF3 center dot dmso forms a dimer and [Pt(dpppa-2H)]center dot(AgO2CCF3)(2) forms a coordination polymer in the solid state.