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- Title
Homo- and Heterodinuclear Ir and Rh Imine-functionalized Protic NHC Complexes: Synthetic, Structural Studies, and Tautomerization/Metallotropism Insights.
- Authors
He, Fan; Wesolek, Marcel; Danopoulos, Andreas A.; Braunstein, Pierre
- Abstract
The influence of the potentially chelating imino group of imine-functionalized Ir and Rh imidazole complexes on the formation of functionalized protic N-heterocyclic carbene (pNHC) complexes by tautomerization/metallotropism sequences was investigated. Chloride abstraction in [Ir(cod)Cl{C3H3N2(DippN=CMe)-κN3}] ( 1 a) (cod=1,5-cyclooctadiene, Dipp=2,6-diisopropylphenyl) with TlPF6 gave [Ir(cod){C3H3N2(DippN=CMe)-κ2(C2,Nimine)}]+[PF6]− ( 3 a+[PF6]−). Plausible mechanisms for the tautomerization of complex 1 a to 3 a+[PF6]− involving C2−H bond activation either in 1 a or in [Ir(cod){C3H3N2(DippN=CMe)-κN3}2]+[PF6]− ( 6 a+[PF6]−) were postulated. Addition of PR3 to complex 3 a+[PF6]− afforded the eighteen-valence-electron complexes [Ir(cod)(PR3){C3H3N2(DippN=CMe)-κ2(C2,Nimine)}]+[PF6]− ( 7 a+[PF6]− (R=Ph) and 7 b+[PF6]− (R=Me)). In contrast to Ir, chloride abstraction from [Rh(cod)Cl{C3H3N2(DippN=CMe)-κN3}] ( 1 b) at room temperature afforded [Rh(cod){C3H3N2(DippN=CMe)-κN3}2]+[PF6]− ( 6 b+[PF6]−) and [Rh(cod){C3H3N2(DippN=CMe)-κ2(C2,Nimine)}]+[PF6]− ( 3 b+[PF6]−) (minor); the reaction yielded exclusively the latter product in toluene at 110 °C. Double metallation of the azole ring (at both the C2 and the N3 atom) was also achieved: [Ir2(cod)2Cl{μ-C3H2N2(DippN=CMe)-κ2(C2,Nimine),κN3}] ( 10) and the heterodinuclear complex [IrRh(cod)2Cl{μ-C3H2N2(DippN=CMe)-κ2(C2,Nimine),κN3}] ( 12) were fully characterized. The structures of complexes 1 b, 3 b+[PF6]−, 6 a+[PF6]−, 7 a+[PF6]−, [Ir(cod){C3HN2(DippN=CMe)(DippN=CH)(Me)-κ2(N3,Nimine)}]+[PF6]− ( 9+[PF6]−), 10⋅ Et2O ⋅toluene, [Ir2(CO)4Cl{μ-C3H2N2(DippN=CMe)-κ2(C2,Nimine),κN3}] ( 11), and 12⋅2 THF were determined by X-ray diffraction.
- Subjects
IMINES; ORGANONITROGEN compounds; IMIDAZOLES; CYCLOOCTADIENE; DIOLEFINS
- Publication
Chemistry - A European Journal, 2016, Vol 22, Issue 8, p2658
- ISSN
0947-6539
- Publication type
Article
- DOI
10.1002/chem.201504030