Synthesis, characterization, and fiber-optic infrared reflectance spectroelectrochemical studies of some dinitrosyl iron diphosphine complexes Fe(NO)2L2 (L = P(C6H4X)3)

Article abstract of DOI:10.1016/j.jorganchem.2013.12.040

A series of iron dinitrosyl complexes of the form Fe(NO) ₂(P(C₆H₄X)₃)₂ (X = p-OMe (1), p-Me (2), m-Me (3), p-H (4), p-F (5), p-Cl (6), p-CF₃ (7)) has been prepared from the reactions of Fe(NO)₂(CO)₂ and the respective triarylphosphines. Complexes 1-7 have been characterized by IR and ³¹P NMR spectroscopy, and by X-ray crystallography for 1 and 7. In general, the compounds with the more basic phosphines display lower υ_NO stretches in the IR spectra than those with the less basic phosphines, and the trends in υ_NO as a function of Hammett parameter and solvent donor/acceptor number were analyzed. The redox behavior of compounds 1-7 in CH₂Cl₂ were studied by cyclic voltammetry at a Pt electrode. In general, the compounds undergo one-electron oxidations. Infrared spectroelectrochemistry revealed that the oxidations generate the derivatives with υ_NOs that are ～100 cm ^-1 higher in energy indicative of Fe(NO)₂-centered oxidations.