The direct electrochemical synthesis of the novel copper(I) complex Cu2[OC6Cl4(OH)]2[(C6H5)2PCH2P(C6H5)2]2

Abstract

The electrochemical oxidation of copper in an acetonitrile solution of an aromatic diol (R(OH)2 = catechol, tetrachloro-1,2-dihydroxybenzene, 2,2'-dihydroxybiphenyl) gives soluble copper(I) products which are reduced to copper at a platinum cathode. In the presence of R(OH)2 + L (L = 2,2'-bipyridine, triphenylphosphine, bis(diphenylphosphino)methane (= dppm)), the products are adducts of copper(I) species in which the anionic ligand is [R(O)OH]−. The crystal structure of Cu2[OC6Cl4(OH)]2(dppm)2 is triclinic, with a = 22.418(5) Ǻ b = 1.784(4) Ǻ, c = 13.492(4) Ǻ, α = 61.63(2)°, β = 86.66(2)°, γ = 80.61(2), V = 3093(2) Ǻ3, Z = 2, and space group [Formula: see text] The molecule consists of a Cu—P—C—P—Cu—P—C—P ring, with copper ligated by [R(O)OH]− groups external to this. Intramolecular O—H—O hydrogen-bonding contributes to the stabilization of this novel complex. Key words: Copper, electrochemical synthesis, hydrogen bonding, aromatic diols, crystal structure.