APPLICATION OF AMINE ELIMINATION FOR THE EFFICIENT PREPARATION OF ELECTROPHILIC ANSA-MONOCYCLOPENTADIENYL GROUP-4 COMPLEXES CONTAINING AN APPENDED AMIDO FUNCTIONALITY - STRUCTURAL CHARACTERIZATION OF [(C5H4) SIME(2)(N-T-BU)] ZRCL2 (NME(2)H)

The homologous series of ansa-monocyclopentadienyl amido complexes [(C 5H4)SiMe(2)(N-t-Bu)]M(NMe(2))(2) (M = Ti (2), Zr (3), Hf (4)) and [(C( 5)Me(4))SiMe(2)(N-tr-Bu)]Zr(NMe(2))(2) (8) are prepared in 70-85% isol ated yields by heating the neat 1:1 reaction mixture of (C(5)R(4)H)SiM e(2)(N(H)-t-Bu), where R = H, Me, and M(NMe(2))(4), at 110-120 degrees C for 24-48 h under a N-2 purge. Whereas the reactions of 2 with 2 eq uiv of [NEt(3)H]Cl or HCI produce a mixture of [(C5H4)siMe(2)(N-t-Bu)] TiCl2 (5) and [(C5H4)SiMe(2)Cl]TiCl2(NMe(2))(NMe(2)H) (6), the reactio n of 2 with SiMes(3)Cl in toluene provides a suitable route for the qu antitative 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 [(C5H4)SiMe(2)(N-t-Bu)]ZrCl2(NMe2H) (7) and the dichloride deri vative [(C(5)Me(4))SiMe(2)(N-t-Bu)]ZrCl2 (1), respectively. Compounds 1-8 have been characterized in solution by NMR measurements, and the m olecular structures of 2, 7, and 8 have been determined by X-ray cryst allography. 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) Angstrom and 105.5, 101.1, 100.2 degrees, respectively.