title: Influence of Electronic Effects on the Reactivity of Triazolylidene-Boryl Radicals: Consequences for the use of N-Heterocyclic Carbene Boranes in Organic and Polymer Synthesis.
abstract: A small library of triazolylidene-boranes that differ only in the nature of the aryl group on the external nitrogen atom was prepared. Their reactivity as hydrogen-atom donors, as well as that of the corresponding N-heterocyclic carbene (NHC)-boryl radicals toward methyl acrylate and oxygen, was investigated by laser flash photolysis, molecular orbital calculations, and ESR spin-trapping experiments, and benchmarked relative to the already known dimethyltriazolylidene-borane. The new NHC-boranes were also used as co-initiators for the Type I photopolymerization of acrylates. This allowed a structure-reactivity relationship with regard to the substitution pattern of the NHC to be established and the role of electronic effects in the reactivity of NHC-boryl radicals to be probed. Although their rate of addition to methyl acrylate depends on their electronegativity, the radicals are all nucleophilic and good initiators for photopolymerization reactions.
authors.affiliation: Institut de Science des Matériaux de Mulhouse IS2M - UMR CNRS 7361, Université de Haute-Alsace, 15 rue Jean Starcky, 68057 Mulhouse Cedex (France), Fax: (+33) 3-89-33-60-69.
authors.forename: Sofia
authors.initials: S
authors.lastname: Telitel
authors.affiliation: ICSN CNRS, Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex (France).
authors.forename: Anne-Laure
authors.initials: AL
authors.lastname: Vallet
authors.affiliation: Department of Chemistry, Colorado State University, Fort Collins, CO 80523 (USA).
authors.forename: Darrin M
authors.initials: DM
authors.lastname: Flanigan
authors.affiliation: Institut de Science des Matériaux de Mulhouse IS2M - UMR CNRS 7361, Université de Haute-Alsace, 15 rue Jean Starcky, 68057 Mulhouse Cedex (France), Fax: (+33) 3-89-33-60-69.
authors.forename: Bernadette
authors.initials: B
authors.lastname: Graff
authors.affiliation: Institut de Science des Matériaux de Mulhouse IS2M - UMR CNRS 7361, Université de Haute-Alsace, 15 rue Jean Starcky, 68057 Mulhouse Cedex (France), Fax: (+33) 3-89-33-60-69.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Morlet-Savary
authors.affiliation: Department of Chemistry, Colorado State University, Fort Collins, CO 80523 (USA).
authors.forename: Tomislav
authors.initials: T
authors.lastname: Rovis
authors.affiliation: Institut de Science des Matériaux de Mulhouse IS2M - UMR CNRS 7361, Université de Haute-Alsace, 15 rue Jean Starcky, 68057 Mulhouse Cedex (France), Fax: (+33) 3-89-33-60-69. jacques.lalevee@uha.fr.
authors.forename: Jacques
authors.initials: J
authors.lastname: Lalevée
authors.affiliation: ICSN CNRS, Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex (France). emmanuel.lacote@univ-lyon1.fr.|Université de Lyon, Institut de chimie de Lyon, UMR 5265 CNRS-Université Lyon I-ESCPE Lyon, 43 Bd du 11 novembre 1918, 69616 Villeurbanne Cedex (France), Fax: (+33) 4-72-43-17-95. emmanuel.lacote@univ-lyon1.fr.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Lacôte
mesh_terms: D001880:Boranes / Q000737:chemistry*; D005609:Free Radicals / Q000737:chemistry*; D006571:Heterocyclic Compounds / Q000737:chemistry*; D008697:Methane / Q000031:analogs & derivatives* / Q000737:chemistry; D015394:Molecular Structure; D055668:Photochemical Processes; D058105:Polymerization; D013237:Stereoisomerism; D014230:Triazoles / Q000737:chemistry*
chemical_list: D001880:Boranes; D005609:Free Radicals; D006571:Heterocyclic Compounds; D014230:Triazoles; C030011:carbene; D008697:Methane
keywords: boranes; carbenes; polymerization; radical reactions; radicals