Department of Chemistry, York University, 4700 Keele Street, Toronto, Ontario M3J 1P3, Canada.
Dalton Trans. 2012 Aug 28;41(32):9651-8. doi: 10.1039/c2dt31004j. Epub 2012 Jul 9.
Free imine imidazol-2-imine ligands with two different substitution patterns have been isolated for the first time and they were found to exist as an equilibrium mixture of geometric and mesomeric isomers. The relative ratios of these isomers are dependent on both the nature of the substituents and of the solvent. The synthesis of the titanium(IV) alkyl and arylimido complexes of these ligands was unexpectedly found to be very selective and was successfully achieved only with the lesser sterically-demanding 2,4,6-trimethylphenyl derivative IMesN^Imine 2a. The solid-state structure of the alkylimido complex further confirms the zwitterionic character of the ligand. The isolated titanium imido complexes were found to be active catalysts for the polymerisation of ethylene.
首次分离出具有两种不同取代模式的游离亚胺亚咪唑啉配体，发现它们以几何和中介异构体的平衡混合物形式存在。这些异构体的相对比例既取决于取代基的性质，也取决于溶剂的性质。令人意外的是，这些配体的钛（IV）烷基和芳基亚氨基配合物的合成非常具有选择性，只有在空间位阻要求较低的 2,4,6-三甲基苯基衍生物 IMesN^Imine 2a 时才成功实现。烷基亚氨基配合物的固态结构进一步证实了配体的两性离子特性。分离出的钛亚氨基配合物被发现是乙烯聚合的有效催化剂。
