title: Synthesis and Characterization of Iron Complexes based on Bis-Phosphinite PONOP and Bis-Phosphite PONOP Pincer Ligands.
abstract: A series of bis-phosphinite and bis-phosphite PONOP iron complexes were prepared and characterized by NMR and IR spectroscopy. Bis-phosphinite PONOP iron dichloride complexes (RPONOP)FeCl2(RPONOP = 2,6-(R2PO)2(C5H3N) and R =iPr,tBu) were prepared through complexation of the free ligands with FeCl2and their solid-state structures were determined. Bis-phosphite PONOP iron complexes (OEtPONOP)Fe(PMe3)2and (CatPONOP)Fe(PMe3)2(Cat = catechol) were synthesized through complexation of the free ligands to Fe(PMe3)4. Carbonyl complexes of both bis-phosphinite and bis-phosphite PONOP were prepared and characterized by IR. The monocarbonyl (iPrPONOP)Fe(CO)Cl2was accessed through exposure of (iPrPONOP)FeCl2to an atmosphere of CO and the CO stretching frequency was observed at 1969 cm-1. Dicarbonyl complexes (iPrPONOP)Fe(CO)2and (OEtPONOP)Fe(CO)2were accessed through reduction of the corresponding chloride complexes with sodium amalgam under a CO atmosphere. Carbonyl stretching frequencies for (iPrPONOP)Fe(CO)2and (OEtPONOPFe)(CO)2were observed at 1824 and 1876 cm-1, and at 1871 and 1927 cm-1respectively. The bis-phosphite PONOP complexes exhibit a less electron rich metal center than the bis-phosphinite PONOP complexes, as would be expected based on the stronger π-acceptor character of these ligands. The electronic properties of the bis-phosphinite PONOP and bis-phosphite PONOP iron complexes are intermediate between previously reported PNP and PDI iron complexes, with the PONOP ligands exhibiting stronger electron donating ability than PDI ligands, but promoting a less electron rich metal center than found in analogous PNP iron complexes.
authors.affiliation: Department of Chemistry and Biochemistry, California State University Northridge, Northridge, California 91330, United States.
authors.forename: Wing-Sy W
authors.initials: WS
authors.lastname: DeRieux
authors.affiliation: Department of Chemistry and Biochemistry, California State University Northridge, Northridge, California 91330, United States.
authors.forename: Aaron
authors.initials: A
authors.lastname: Wong
authors.affiliation: Department of Chemistry and Biochemistry, California State University Northridge, Northridge, California 91330, United States.
authors.forename: Yann
authors.initials: Y
authors.lastname: Schrodi
keywords: Bis-phosphinite pyridine ligands; Bis-phosphite pyridine ligands; Iron pincer complexes