New Cu(I) and Ag(I) binuclear complexes containing the dppa ligand

New Cu(I) and Ag(I) binuclear complexes were prepared by reaction of [M(NCCH3)4][PF6] (M = Ag, Cu) with the bidentate phosphine ligands Ph2PNHPPh2 (dppa) and Ph2PCH2PPh2 (dppm). In the reaction of Cu(I) with dppa the phosphine is easily oxidized to give the octahedral species of [Cu(dppaO2)3][PF6], 1. In an inert atmosphere, the binuclear complexes [Cu2(dppa)2(NCCH3)3][PF6]2, 2, [Cu2(dppa)2(NCCH3)4][PF6]2, 3, [Ag2(dppa)2(NCCH3)2][PF6]2, 4, and [Ag2(dppm)2][PF6]2, 5, were formed and structurally characterized by X-ray diffraction (except for 5). The electrochemical studies showed that the most relevant property of the binuclear species was the ease of forming the metal upon reduction. EH and DFT calculations were performed in order to try and understand the structural features of the [M2(dppa)2(NCCH3)x]n+ complexes, including the 0.47 Å increase in MM distance upon going from 2 to 3