Approaches to bi- and trimetallic platinum and palladium complexes using the DPPEPM ligand

Bis{(diphenylphosphinoethyl)phenylphosphino}methane (DPPEPM) reacts with [PtR2(cod)] in 1:1 ratio to give [PtR2(DPPEPM-PP)] (2a, R=Me; 2b, R=Ph), whereas with [PtCl2(cod)] or [PdCl2(cod)] it yields the ionic species [M(DPPEPM-PP)2]2+ (3 and 4). With [MClMe(cod)], the product is [MMe(DPPEPM-PPP)]+ (5, M=Pt; 6, M=Pd), in which one of the internal P atoms of the ligand is uncoordinated. These complexes undergo oxidation of the free P atom to give 7 and 8 on standing in solution. Complexes 2–4 may be used to construct bimetallic and trimetallic mixed metal complexes. The molecular structures of 7 and [PtMe2(μ-DPPEPM)PdCl2] (11) are reported.