SYNTHESIS AND X-RAY CRYSTAL-STRUCTURE OF THE COPPER(I) DICARBOXYLIC-ACID COMPLEX [CU(ETA(1)-BDOAH)(PPH(3))(3)] (BDOAH(2) = BENZENE-1,2-DIOXYACETIC ACID)

The copper(II) complex [Cu(bdoa)(H2O)(2)] (bdoaH(2) = benzene-1,2-dioxyacetic acid) reacts with triphenylphosphine (1:4 mol ratio) to give the colourless copper(I) complex [Cu(eta(1)-bdoaH) (PPh(3))(3)] (1) in good yield. The X-ray crystal structure of the complex shows the copper atom at the centre of a distorted tetrahedron, and is ligated by the phosphorus atoms of the three triphenylphosphines and one carboxylate oxygen atom of the bdoaH(-) ligand. Significant intermolecular hydrogen-bonding exists between the pendant carboxylate OH function of one molecule and the uncoordinated ''ketonic'' oxygen of a neighbouring molecule. Complex 1 is non-conducting in chloroform but ionizes readily in acetonitrile. The cyclic voltammogram of an acetonitrile solution of 1 shows a single irreversible anodic peak for the oxidation of the PPh(3) ligands and the copper(I) centre, and a single irreversible cathodic peak for the reduction of the bdoaH(-) ion. IR and mass spectral data for 1 are given.