Structural characterizations of coordination complexes of bis-triphenylphosphine copper(I) dicarboxylates

Dicarboxylate complexes of copper(I) with triphenylphosphine have been prepared in high yield from copper(I) butyrate and 0.5 equiv. of the corresponding dicarboxylic acid. The bis-triphenylphosphine copper(I) glutarate, adipate and terephthalate salts thus synthesized have been structurally characterized by single-crystal X-ray diffraction studies. The structures consist of two copper(I) centres each bound to two triphenylphosphine ligands with the metal centres bridged by the dicarboxylate group. In each of these derivatives the geometry about copper(I) is that of a distorted tetrahedron with a varying degree of asymmetry in the chelating carboxylate ligand. For example, in the (Ph(3)P)(2)Cu(O2C(CH2)(4)CO2)Cu(Ph(3)P)(2) complex the Cu-O bond distances at a single copper centre vary by 0.125 Angstrom. Even more dramatic Cu-O bond length differences were noted in the glutarate analogue. Nevertheless, in this instance the asymmetry in Cu-O bond lengths were found to be influenced by the presence of solvent molecules in the crystal lattice, hence some of the asymmetry seen in the solid-state may be due to crystal packing forces. Copyright (C) 1996 Elsevier Science Ltd.