INVESTIGATION OF NICKEL (II)-OXIMATE COMPLEXES THAT REACT WITH MOLECULAR OXYGEN

Ni(II) complexes containing amidates and thiolates have been shown to react with O2 via irreversible ligand oxidation. We have constructed a series of Ni(II) complexes based on a tripodal amine bis(oxime) ligand framework. These complexes display oxygen reactivity upon deprotonation of the oximes without requiring irreversible ligand oxidation. This project investigated the reaction involving one of the complexes in the library, [Ni(TRISOXH 3 )(NO 3 )(H 2 O)](NO 3 )· (H 2 O), where TRISOXH 3 = (tris(1-propan-2-onyl oxime)amine). It was discovered that the reaction of this complex with molecular oxygen is contingent upon the presence of a source of hydrogen atoms. This two-hydrogen atom donor acts as a substrate. Several primary alcohols, including the relatively inert methanol, and amines were catalytically oxidized by this reaction. Spectroscopic analysis using a variety of techniques has demonstrated that reversible oxidation occurs on the oximate nitrogen to form an iminoxyl radical. Many of the other complexes in the series were also investigated to examine their electronic structure, their electrochemical properties, and their ability to oxidize methanol.