Mixed-ligand complexes of copper(I) with diimines and phosphines: Effective catalysts for the coupling of phenylacetylene with halobenzene

New copper(I) mixed-ligand complexes 1-4 of the formula Cu(N-N)PR3X, where N-N = 1,10-phenanthroline (phen), 2,2'-bipyridine (bpy), 5,5'-dimethyl-2,2'-bipyridine (5,5'dimbpy) and PR3 = tricyclohexylphosphine, tris(2-cyanoethyl)phosphine and isopropyldiphenylphosphine, have been synthesized. The complexes were characterized by EA. IR, NMR and single crystal X-ray diffraction. The solution fluorescence emission spectra were measured. The single crystal X-ray analysis showed that the copper(I) ion is four-coordinate with a distorted tetrahedral geometry. The complexes catalyze the formation of diphenylacetylene from the coupling of halobenzene with phenyl acetylene. The complex Cu(5,5'-dimethylbpy)P(cyhexyl)(3)I showed the highest catalytic activity. At room temperature all four complexes exhibit, in dichloromethane, emission maxima in the 329-344 nm range, corresponding to intra-ligand excited states. (C) 2009 Elsevier Ltd. All rights reserved.