Tris(phosphinoamide) Zirconium Complexes as New Tripod-type Metalloligand;Construction of Novel ELHB Complexes

摘要

Phosphines are one of the most visible and useful auxiliary ligands in organometallic and synthetic organic chemistry. Recently, we reported a unique bidentate phosphorus ligand having a Lewis acidic Ti(IV) center, (Ph_2PN~tBu)_2TiCl_2(1). Treatment of 1 with square planarly coordinated Pt(II) species afforded Ti-Pt heterobimetallic complexes having the dative bond from fully-occupied d_z~2 orbital of Pt to Lewis acidic Ti center. Whereas, reaction of 1 with tetrahedrally arranged Ru(II) species gave rise to Ti-Ru complex with intramolecular Lewis acid - base interaction between the lone pair of Cl atom and the titanium center (Scheme 1). As chemistry on this line, we were interested in replacing the bidentate metalloligand to tridentate phosphorus metalloligands. In this paper, we report the synthesis of tris(phosphinoamide) zirconium complexes, and their application to the tripod-type metalloligand in the reaction with square planarly or tetrahedrally arranged late transition metals.