Conformationally Rigid Diamide Complexes:  Synthesis and Structure of Titanium(IV) Alkyl Derivatives

Titanium complexes bearing a pyridinediamide ligand [2,6-(RNCH 2 ) 2 NC 5 H 3 ] 2- (R = 2,6-diisopropylphenyl (BDPP); R = 2,6-dimethylphenyl (BDMP)) have been synthesized. The dichloride complexes [2,6-(RNCH 2 ) 2 NC 5 H 3 ]TiCl 2 are prepared in high yield from {2,6-[(Me 3 Si)RNCH 2 ] 2 NC 5 H 3 } and TiCl 4 via the elimination of 2 equiv of CiSiMe 3 . Mono(alkyl) and bis(alkyl) complexes are prepared from [2,6-(RNCH 2 ) 2 NC 5 H 3 ]TiCl 2 and various Grignard reagents. A single-crystal X-ray diffraction study of (BDMP)TiBr(CH 2 CMe 2 Ph)·C 6 H 6 ( 8b ·C 6 H 6 ) revealed a distorted square pyramid structure with the neophenyl group occupying the axial position.