title: Direct estimate of the internal π-donation to the carbene centre within N-heterocyclic carbenes and related molecules.
abstract: Fifteen cyclic and acylic carbenes have been calculated with density functional theory at the BP86/def2-TZVPP level. The strength of the internal X→p(π) π-donation of heteroatoms and carbon which are bonded to the C(II) atom is estimated with the help of NBO calculations and with an energy decomposition analysis. The investigated molecules include N-heterocyclic carbenes (NHCs), the cyclic alkyl(amino)carbene (cAAC), mesoionic carbenes and ylide-stabilized carbenes. The bonding analysis suggests that the carbene centre in cAAC and in diamidocarbene have the weakest X→p(π) π-donation while mesoionic carbenes possess the strongest π-donation.
authors.affiliation: Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Strasse, D-35032 Marburg, Germany.
authors.forename: Diego M
authors.initials: DM
authors.lastname: Andrada
authors.affiliation: Laboratoire International Associé Centre National de la Recherche Scientifique - UMR 7565, Université de Lorraine, 54506 Vandoeuvre-lès-Nancy, France.
authors.forename: Nicole
authors.initials: N
authors.lastname: Holzmann
authors.affiliation: Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Strasse, D-35032 Marburg, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Hamadi
authors.affiliation: Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Strasse, D-35032 Marburg, Germany.
authors.forename: Gernot
authors.initials: G
authors.lastname: Frenking
keywords: N-heterocyclic carbenes; bonding analysis; π-donation