Synthesis and structural characterization of dimeric phosphine ylide Cu(I) complexes: Application in Suzuki cross-coupling reactions and biological evaluation as antibacterial agents

Abstract

In this work we report the synthesis of the complexes of the type [Cu(μ-Cl){Ph2P(CH2)nPPh2C(H)C(O)PhR}]2 (n = 1: R = Cl (1), NO2 (2); n = 2: R = Cl (3), NO2 (4)) derived from the reactions of the copper(I) chloride with related phosphorus ylides in equimolar ratios using dry methanol as solvent. The identity of complex 1 was unequivocally determined by single crystal X-ray diffraction techniques, its structure consisting of five-membered rings formed by coordination of the ligands through the phosphine group and the ylidic carbon atom to the metal center. The coordination geometry around the Cu atoms in this complex can be defined as slightly distorted tetrahedral. Characterization of the obtained compounds was also performed by IR, 1H, 31P and 13C NMR spectroscopy and analytical data indicated a 1:1 stoichiometry between the Cu(I) chloride and ylide. Well-defined phosphine bis-ylide Cu(I) complexes 1 and 3 were found to be an effective catalyst for the Suzuki coupling of various aryl halides including with 4-ethyl phenylboronic acid, giving the desired coupling products at low catalyst loading in moderate to good yields. Also, the antibacterial activities of DMSO-solved complexes were measured by disc diffusion method against 6 Gram positive and negative bacteria. All Cu(I) complexes exhibited antibacterial activities against bacteria tested especially Gram negative ones.