A family of cationic divalent metal complexes (M = Mn, Fe, Co) using tris[(tetramethylguanidino)phenyl]amine and the corresponding bipodal congener (N-methyl-bis[(tetramethylguanidino)phenyl]amine) was synthesized and characterized. The tripodal complexes were obtained from the reaction of the corresponding ligand with [M(NCMe)6](PF6)2 precursors. Alternatively, the bipodal complexes were prepared via a two step process, initially via the reaction between the corresponding ligands and metal chlorides (MnCl2, FeCl2 and CoCl2), followed by removal of chloride with TlPF6 in MeCN to afford acetonitrile adducts. The characterization of this family of cationic complexes exhibited stoichiometric variations and structural complexities, with the expected result that the bipodal analogues offered additional coordination sites for catalytic studies as compared to the tripodal complexes. An extensive comparative study was then carried out with this library of reagents involving nitrene-transfer chemistry towards aziridination of olefins. Most importantly, additional reactivity was observed, signaling formation of five-membered heterocycles (pyrrolidines and imidazolines) in the presence of excess olefins or acetonitrile. The catalytic reactions were then judiciously optimized with the most productive iron reagents, and mechanistic studies uncovered the dual role of the metal as a nitrene-transfer agent and a Lewis acid.

Nitrene transfer reactions mediated by guanidine supported transition metal (MnII,FeII, CoII) complexes with applications towards (3+2) cycloaddition reactions

Where thousands of chemistry professionals meet to share ideas and advance scientific and technical knowledge. Spring 2023 abstracts, posters, and presentations will launch at the end of March.

ACS Spring 2023

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.