A combined experimental and theoretical study of dinitrosyl iron complexes containing chelating bis(diphenyl)phosphinoX (X = benzene, propane and ethylene): X-ray crystal structures and properties influenced by the presence or absence of π-bonds in chelating ligands.

Recent discoveries involving the roles of nitric oxide in humans have stimulated intense interest in transition metal nitrosyl complexes. A series of dinitrosyl iron complexes with the formula [(DPPX)Fe(NO)], {DPPX = 1,2-bis(diphenylphosphino)benzene (), 1,3-bis(diphenylphosphino)propane (), and cis-1,2-bis(diphenylphosphino)ethylene ()} has been prepared and characterized through a combination of FT-IR, NMR, UV-vis, X-ray crystallography, and electrochemical techniques. Infrared spectroscopy showed NO shifts to the region of 1723 and 1674 cm for complexes and , and 1708 and 1660 cm for , indicating that ligand acts as a stronger σ-donor.