Synthesis, structure, spectroscopic properties, and photochemistry of homo- and heteropolynuclear copper(I) complexes bridged by the 2,5-bis(2-pyridyl)pyrazine ligand

Cu(I)-Cu(I) and Cu(I)-Ru(II) dinuclear complexes bridged by the 2,5-bppz (2,5-bis(2-pyridyl)pyrazine) ligand have been prepared and characterized including the X-ray crystallographic study of the dinuclear [{Cu-1(PPh3)2}(2)(mu-2,5-bppz)](PF6)(2)(.)2CH(3)CI complex: a = 13.974(2), b = 13.993(2), c = 13.537(2) angstrom; alpha = 101.98(1), beta = 103.22(1), gamma = 113.90(1)degrees; triclinic, P1, Z= 1. The trinuclear [{(bpy)(2)Ru-II(mu-2,5-bppz)}(2)Cu-1](PF6)(5) complex was also prepared, and the structure of the complex in solution was studied by spectrometric titration. The dinuclear Cu(I) complex and [(bpy)(2)Ru-II(mu-2,5-bppz)Cu-1(PPh3)(2)](PF6)(5) show photoluminescence in the solid state, which should arise from MLCT states, Photochemical oxidation of the trinuclear (Ru2CuI)-Cu-II complex occurs in the presence of oxygen to give a (Ru2CuII)-Cu-II complex. The MLCT states and the redox reaction in the excited state are discussed.