title: Ligand transformations and efficient proton/water reduction with cobalt catalysts based on pentadentate pyridine-rich environments.
abstract: A series of cobalt complexes with pentadentate pyridine-rich ligands is studied. An initial Co(II) amine complex 1 is prone to aerial oxidation yielding a Co(III) imine complex 2 that is further converted into an amide complex 4 in presence of adventitious water. Introduction of an N-methyl protecting group to the ligand inhibits this oxidation and gives rise to the Co(II) species 5. Both the Co(III) 4 and Co(II) 5 show electrocatalytic H2 generation in weakly acidic media as well as in water. Mechanisms of catalysis seem to involve the protonation of a Co(II)-H species generated in situ.
authors.affiliation: Department of Chemistry, Wayne State University, 5101 Cass Ave, Detroit, MI 48202 (USA) http://chem.wayne.edu/veranigroup/
authors.forename: Debashis
authors.initials: D
authors.lastname: Basu
authors.forename: Shivnath
authors.initials: S
authors.lastname: Mazumder
authors.forename: Xuetao
authors.initials: X
authors.lastname: Shi
authors.forename: Habib
authors.initials: H
authors.lastname: Baydoun
authors.forename: Jens
authors.initials: J
authors.lastname: Niklas
authors.forename: Oleg
authors.initials: O
authors.lastname: Poluektov
authors.forename: H Bernhard
authors.initials: HB
authors.lastname: Schlegel
authors.forename: Cláudio N
authors.initials: CN
authors.lastname: Verani
keywords: CoIH− species; cobalt complexes; proton reduction; pyridine ligands; water reduction