Steric factors on unsymmetrical O -hydroxyaryl N -Heterocyclic carbene ligands prevailing the stabilization of single stereoisomer of bis-ligated titanium complexes
作者:Coralie C. Quadri、Ralte Lalrempuia、Nils Åge Frøystein、Karl W. Törnroos、Erwan Le Roux
DOI:10.1016/j.jorganchem.2018.02.018
日期:2018.4
Bis-ligated titanium (IV) metal complexes supported by bidentate unsymmetrical o-hydroxyaryl-substituted N-heterocyclic carbene ligands were synthesized and structurally identified. While the direct addition of the doubly deprotonated bulky imidazolidinium chloride salts [Dipp,4-RNHC-H]Cl (with Dipp = 2,6-diisopropylphenyl, R = H (2-hydroxyphenyl), and R = Me (2-hydroxy-4-methyl-phenyl)) with chloro-titanium
合成并结构鉴定了由双齿不对称的邻羟基芳基取代的N-杂环卡宾配体支撑的双连接的钛(IV)金属配合物。直接添加双去质子化的笨重的咪唑烷基氯化铵盐[ Dipp,4-R NHC-H] Cl(Dipp = 2,6-二异丙基苯基,R = H(2-羟基苯基),R = Me(2-羟基-4-甲基-苯基))与氯钛前体有利于单一立体异构体对应于所述双连接的钛络合物的形成的反式- ([κ 2 -C,O] -迪普,4- [R NHC)2的TiCl 2(对于4a H, R = H(2-羟基苯基),R = Me(2-羟基-4-甲基-苯基,对于4a Me而言),与位阻较少的咪唑氯化铵盐[ Mes,H NHC-H] Cl和[ Dep,H NHC-H] Cl的反应性为protio配体(用MES = 2,4,6-三甲基苯基和DEP = 2,6-二乙基苯基)没有导致单一立体异构体,但重新被安排成四齿salophen状络合物的顺式-