title: Characterization of beta-B-agostic isomers in zirconocene amidoborane complexes.
abstract: The reaction of Cp(x)(2)ZrCl(2) (Cp(x) = Cp, Cp*) with ammonia borane in presence of n-butyllithium yielded Cp(2)Zr(Cl)NH(2)BH(3) and Cp(x)(2)Zr(H)NH(2)BH(3). These derivatives are isoelectronic with the ethyl zirconocene chloride and hydride, respectively, and feature a chelating amidoborane ligand coordinating through a Zr-N bond and a Zr-H-B bridge. In solution, each of the complexes consists of an equilibrium mixture of two isomers differing in the orientation of the amidoborane ligand with respect to the Zr-X bond (X = H, Cl), while in the solid state, only one isomer was observed. Such isomers have not been characterized for any metal complexes containing the isoelectronic beta-agostic ethyl ligand or any other agostic alkyl group.
authors.affiliation: Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, AB, T2N 1N4 Canada.
authors.forename: Taryn D
authors.initials: TD
authors.lastname: Forster
authors.forename: Heikki M
authors.initials: HM
authors.lastname: Tuononen
authors.forename: Masood
authors.initials: M
authors.lastname: Parvez
authors.forename: Roland
authors.initials: R
authors.lastname: Roesler