Isomerism in Hexacoordinate Ti(IV) and Zr(IV) Complexes with a Tetradentate ONNO‐ Schiff Base Ligand

The reactions of [(thf) 2 TiCl 4 ] with sodiated 2,2’‐bis[2‐hydroxy‐3,5‐di( tert ‐butyl)benzylideneamino]‐1,1’‐biphenyl ( 1 a ) and 2,2’‐bis[2‐hydroxy‐3,5‐di( tert ‐butyl)benzylideneamino]‐4,4’‐dimethyl‐1,1’‐biphenyl ( 1 b ) yield the corresponding Ti complexes 2 a and 2 b . Similarly, 1 a reacts with [(thf) 2 ZrCl 4 ] to the corresponding Zr derivative 3 . For 2 a , a mixture of cis‐β and trans isomers were observed in solution whereas the Zr congener exclusively forms the cis‐α form. Quantum chemical calculations verify that these isomers are the preferred molecular structures. The crystal structures of cis‐β isomeric 2 a and cis‐α isomeric 3 have been determined. Metalation of 1 a with Ti(NMe 2 ) 4 yields 2,2’‐bis[(2‐oxido‐3,5‐di(tert‐butyl)phenyl)‐dimethylaminomethylamino]‐1,1’‐biphenyl titanium(IV) ( 4 ) with a hexadentate ligand.