Application of Amine Elimination for the Efficient Preparation of Electrophilic ansa -Monocyclopentadienyl Group 4 Complexes Containing an Appended Amido Functionality. Structural Characterization of [(C 5 H 4 )SiMe 2 (N- t -Bu)]ZrCl 2 (NMe 2 H)

The homologous series of ansa -monocyclopentadienyl amido complexes [(C 5 H 4 )SiMe 2 (N- t -Bu)]M(NMe 2 ) 2 (M = Ti ( 2 ), Zr ( 3 ), Hf ( 4 )) and [(C 5 Me 4 )SiMe 2 (N- t -Bu)]Zr(NMe 2 ) 2 ( 8 ) are prepared in 70−85% isolated yields by heating the neat 1:1 reaction mixture of (C 5 R 4 H)SiMe 2 (N(H)- t -Bu), where R = H, Me, and M(NMe 2 ) 4, at 110−120 °C for 24−48 h under a N 2 purge. Whereas the reactions of 2 with 2 equiv of [NEt 3 H]Cl or HCl produce a mixture of [(C 5 H 4 )SiMe 2 (N- t -Bu)]TiCl 2 ( 5 ) and [(C 5 H 4 )SiMe 2 Cl]TiCl 2 (NMe 2 )(NMe 2 H) ( 6 ), the reaction of 2 with SiMe 3 Cl in toluene provides a suitable route for the quantitative conversion of 2 to 5 . Alternatively, the reactions of 3 and 8 with 2 equiv of [NEt 3 H]Cl or HCl afford solely the dimethylamine adduct [(C 5 H 4 )SiMe 2 (N- t -Bu)]ZrCl 2 (NMe 2 H) ( 7 ) and the dichloride derivative [(C 5 Me 4 )SiMe 2 (N- t -Bu)]ZrCl 2 ( 1 ), respectively. Compounds 1 − 8 have been characterized in solution by NMR measurements, and the molecular structures of 2, 7, and 8 have been determined by X-ray crystallography. The M−N(appended amido) bond distances and Cp(centroid)−M−N bond angles in 2, 7, and 8 are 1.972(4), 2.055(5), 2.108(4) Å and 105.5, 101.1, 100.2°, respectively.