Synthesis of a binuclear copper(I) complex [Cu2(PPh3)6(μ-OOCH)](ClO4) - insertion reaction of carbon dioxide.

A novel binuclear complex [Cu2 (PPh3)2 (µ-OOCH)](ClO4)(II)was synthesized via the interaction of carbon dioxide with [Cu(PPh3)2(BH4)] (I) in the presence of PPh3 and NBu4 (ClO4). It was characterized by elemental analysis and spectroscopic methods as well as by single-crystal X-ray diffraction. Crystals are monoclinic, space group C2/c , with a = 25.911(5), b = 13.6361(3), c = 26.929(5)Å, β = 90.21(3), V = 9323.1(3)Å3, Z = 8 and Dc = 1.314 g cm-3. The formate ligand of II in the solid state displays a near-perfect linear coordination mode as CO2 and serves as a bridge for the two Cu(PPh3)3 units with the O-C-O bond angle being 180.0(5)°. A mechanism involving carbon dioxide insertion into the Cu-H bond of [Cu(PPh3)3(BH4)] (I) for the formation of II is proposed. [ABSTRACT FROM AUTHOR]