Synthesis and structural characterization of heteroleptic Cu(I) complexes with alpha-diimines derived from pyridinyliminobenzoic acids

The synthesis and molecular and electronic structure of heteroleptic univalent copper compounds [Cu(L)(PPh3)X] are reported where X is a halide and L represents 3-pyridinylimino, 4-pyridinylimino or 3,5-dipyridinylimino-substituted benzoic acid, hereafter abbreviated as L1, L2, and L3, respectively. The crystal structures of two iodide and one bromide complexes are described. All compounds are hydrogen-bonded dimers. The electronic excitation spectra of the compounds are dominated by intraligand bands of ligands while characteristic MLCT transitions are observed at 430-480 nm. No emission is observed from the compounds either in the solid state or in solution; on the contrary a photodecomposition is observed resulting in triphenylphosphane ligand elimination and formation of halogen-bridged dimmers.