title: Zirconium complexes stabilized by amine-bridged bis(phenolato) ligands as precatalysts for intermolecular hydroamination reactions.
abstract: A series of zirconium complexes bearing amine-bridged bis(phenolato) ligands of different steric and electronic properties have been synthesized, and their activities in catalyzing intermolecular hydroamination reactions have been studied and compared. In general, hexacoordinate zirconium dibenzyl complexes 1-4 stabilized by [ONNO]- or [ONOO]-type ligands were found to be less active than pentacoordinate complexes 5 and 7 that carry [ONO]-type ligands, which clearly imply that amine-bridged bis(phenolato) ligands play crucial roles in influencing catalytic activities. Complex 5 showed good activities and regioselectivities in catalysing reactions of various primary amines and alkynes. Moreover, reactions of challenging substrates, including secondary amines, internal alkynes, and hydrazines, were achieved with in situ generated cationic species from complex 5 and [Ph3C][B(C6F5)4].
authors.affiliation: Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Materials Science, Dushu Lake Campus, Soochow University, Suzhou 215123, People's Republic of China. yuandan@suda.edu.cn yaoym@suda.edu.cn.
authors.forename: Qiu
authors.initials: Q
authors.lastname: Sun
authors.forename: Yaorong
authors.initials: Y
authors.lastname: Wang
authors.forename: Dan
authors.initials: D
authors.lastname: Yuan
authors.forename: Yingming
authors.initials: Y
authors.lastname: Yao
authors.forename: Qi
authors.initials: Q
authors.lastname: Shen