title: Synthesis, structure, and highly efficient copper-catalyzed aziridination with a tetraaza-bispidine ligand.
abstract: The distorted trigonal-bipyramidal Cu(II) complex [Cu(L(1))(NCCH(3))](2+) of the novel tetradentate bispidine-derived ligand L(1) with four tertiary amine donors (L(1)=1,5-diphenyl-3-methyl-7-(1,4,6-trimethyl-1,4-diazacycloheptane-6-yl)diazabicyclo[3.3.1]nonane-9-one) is a very efficient catalyst for the aziridination of olefins in the presence of a nitrene source. In agreement with the experimental data (in situ spectroscopy, product distribution, and its dependence on the geometry of the substrate and of the nitrene source), a theoretical analysis based on DFT calculations indicates that the active catalyst has the Cu center in its +II oxidation state, that electron transfer is not involved, and that the conversion of the olefin to an aziridine is a stepwise process involving a radical intermediate. The striking change of efficiency and reaction mechanism between classical copper-bispidine complexes and the novel L(1)-based catalyst is primarily attributed to the structural variation, enforced by the ligand architecture.
authors.affiliation: Universität Heidelberg, Anorganisch-Chemisches Institut, INF 270, 69120 Heidelberg, Germany. peter.comba@aci.uni-heidelberg.de
authors.forename: Peter
authors.initials: P
authors.lastname: Comba
authors.forename: Christina
authors.initials: C
authors.lastname: Haaf
authors.forename: Achim
authors.initials: A
authors.lastname: Lienke
authors.forename: Amsaveni
authors.initials: A
authors.lastname: Muruganantham
authors.forename: Hubert
authors.initials: H
authors.lastname: Wadepohl