title: Redox and luminescent properties of robust and air-stable N-heterocyclic carbene group 4 metal complexes.
abstract: Robust and air-stable homoleptic group 4 complexes of the type M(L)2 [1-3; M = Ti, Zr, Hf; L = dianionic bis(aryloxide) N-heterocyclic carbene (NHC) ligand] were readily synthesized from the NHC proligand 1,3-bis(3,5-di-tert-butyl-2-hydroxyphenyl)imidazolinium chloride (H3L,Cl) and appropriate group 4 precursors. As deduced from cyclic voltammetry studies, the homoleptic bis-adduct zirconium and hafnium complexes 2 and 3 can also be oxidized, with up to four one-electron-oxidation signals for the zirconium derivative 2 (three reversible signals). Electron paramagnetic resonance data for the one-electron oxidation of complexes 1-3 agree with the formation of ligand-centered species. Compounds 2 and 3 are luminescent upon excitation in the absorption band at 362 nm with emissions at 485 and 534 nm with good quantum yields (ϕ = 0.08 and 0.12) for 2 and 3, respectively. In contrast, the titanium complex 1 does not exhibit luminescent properties upon excitation in the absorption band at 310 and 395 nm. Complexes 2 and 3 constitute the first examples of emissive nonmetallocene group 4 metal complexes.
authors: Institut de Chimie de Strasbourg, CNRS UMR 7177, Université de Strasbourg , 1 rue Blaise Pascal, 67000 Strasbourg, France.
authors: Charles
authors: C
authors: Romain
authors: Sylvie
authors: S
authors: Choua
authors: Jean-Paul
authors: JP
authors: Collin
authors: Martine
authors: M
authors: Heinrich
authors: Corinne
authors: C
authors: Bailly
authors: Lydia
authors: L
authors: Karmazin-Brelot
authors: Stéphane
authors: S
authors: Bellemin-Laponnaz
authors: Samuel
authors: S
authors: Dagorne
mesh_terms: D004578:Electron Spin Resonance Spectroscopy; D006571:Heterocyclic Compounds / Q000737:chemistry*; D049449:Luminescence; D009682:Magnetic Resonance Spectroscopy; D008670:Metals / Q000737:chemistry*; D008697:Methane / Q000031:analogs & derivatives* / Q000737:chemistry; D010084:Oxidation-Reduction
chemical_list: D006571:Heterocyclic Compounds; D008670:Metals; C030011:carbene; D008697:Methane