title: Jacobsen's catalyst for hydrolytic kinetic resolution: structure elucidation of paramagnetic Co(III) salen complexes in solution via combined NMR and quantum chemical studies.
abstract: NMR investigation of chiral Co(III) salen catalysts, important for enantioselective hydrolytic kinetic resolution (HKR), revealed the presence of a paramagnetic high-spin Co(III) species, which is in solvent- and temperature-dependent equilibrium with the known diamagnetic low-spin Co(III) complex. Combined with quantum chemical DFT calculations, the para- and diamagnetic chemical shifts were used to study the salen ligand conformation of the para- and diamagnetic complexes, resulting in a mechanistic proposal for the enantioselective step in catalysis.
authors.affiliation: Department für Chemie, Universität zu Köln, Greinstrasse 4, 50939 Köln, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Kemper
authors.forename: Peter
authors.initials: P
authors.lastname: Hrobárik
authors.forename: Martin
authors.initials: M
authors.lastname: Kaupp
authors.forename: Nils E
authors.initials: NE
authors.lastname: Schlörer