Synthesis, structural characterization and DFT calculations of a diphenyl-2-pyridylphosphine complex of copper(II)

The reaction of Cu(NO3)(2)<middle dot>3H(2)O with a potentially bidentate P,N-donor ligand, diphenyl-2-pyridylphosphine (PPh2Py), in 1:2 molar ratio resulted in formation of a kappa N-2,O-chelated complex, [Cu(kappa N-2,O-P(O)Ph2Py)(2)(NO3)(2)] (1). A single-crystal X-ray study confirmed the formation of a five-membered kappa N-2, O-chelate involving pyridyl nitrogen and phosphine oxide oxygen donor sites. A DFT study was carried out on 1 to understand the chelate ring expansion process upon oxidation with PPh2Py. DFT analysis revealed that 1 contains a relatively strong M-N bond compared to its M-P bond, facilitating the oxidation of the P atom followed by chelate ring expansion.