title: 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.
abstract: 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)2], {DPPX = 1,2-bis(diphenylphosphino)benzene (1), 1,3-bis(diphenylphosphino)propane (2), and cis-1,2-bis(diphenylphosphino)ethylene (3)} 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-1for complexes1and3, and 1708 and 1660 cm-1for2, indicating that ligand2acts as a stronger σ-donor. The X-ray crystallographic data showed that1and3possess the rarerepulsoconformation while2has theattractoconformation. CV studies on compounds1,2and3display two quasi-reversible oxidations with the E°1/2values at 0.101 and 0.186 V, 0.121 and 0.184 V, and 0.019 and 0.342 V, respectively. The larger ΔE value for compound2compared with that of1and3is attributed to the lack of π-bonds between the two phosphorus atoms. Theoretical calculations using density functional theory were carried out on the synthesized compounds and model compounds and the results are consistent with the experimental data. The calculated HOMO-LUMO gaps for compounds1, 2and3are 3.736, 4.060, and 3.669 eV, respectively, which supports the stronger back-donation for compound2than that of compounds1and3.
authors.affiliation: Department of Chemistry and Biochemistry, California State University, Long Beach, 1250 Bellflower Blvd., Long Beach, CA 90840 USA.
authors.forename: Lauren R
authors.initials: LR
authors.lastname: Holloway
authors.affiliation: Department of Chemistry and Biochemistry, California State University, Long Beach, 1250 Bellflower Blvd., Long Beach, CA 90840 USA.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Clough
authors.affiliation: Department of Chemistry and Biochemistry, California State University, Fullerton, P.O. Box 6866, Fullerton, CA 92834 USA.
authors.forename: Jessica Y
authors.initials: JY
authors.lastname: Li
authors.affiliation: Department of Chemistry and Biochemistry, California State University, Fullerton, P.O. Box 6866, Fullerton, CA 92834 USA.
authors.forename: Emily L
authors.initials: EL
authors.lastname: Tao
authors.affiliation: Department of Chemistry and Biochemistry, California State University, Fullerton, P.O. Box 6866, Fullerton, CA 92834 USA.
authors.forename: Fu-Ming
authors.initials: FM
authors.lastname: Tao
authors.affiliation: Department of Chemistry and Biochemistry, California State University, Long Beach, 1250 Bellflower Blvd., Long Beach, CA 90840 USA.
authors.forename: Lijuan
authors.initials: L
authors.lastname: Li
keywords: DFT calculations; chelating bisphosphines; dinitrosyl iron complexes; spectroscopy