Redox and Luminescent Properties of Robust and Air-Stable N-Heterocyclic Carbene Group 4 Metal Complexes
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- 作者：Charles Romain ; Sylvie Choua ; Jean-Paul Collin ; Martine Heinrich ; Corinne Bailly ; Lydia Karmazin-Brelot ; St茅phane Bellemin-Laponnaz ; Samuel Dagorne
- 刊名：Inorganic Chemistry
- 出版年：2014
- 出版时间：July 21, 2014
- 年：2014
- 卷：53
- 期：14
- 页码：7371-7376
- 全文大小：314K
- ISSN：1520-510X
文摘
Robust and air-stable homoleptic group 4 complexes of the type M(L)2 [1鈥?b>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鈥?b>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 ( = 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.