Mixed amido-cyclopentadienyl group 4 metal complexes

Abstract

The reactivity of substituted half-sandwich complexes of Ti, Zr, and Hf towards 2,6-diisopropylaniline NH₂C₆H₃-2,6-ⁱPr₂ (L^NH) and 2-[(dimethylamino)methyl]aniline NH₂C₆H₄-2-(CH₂NMe₂) (L^NNH) was investigated. Two series of mononuclear complexes (η⁵-C₅Me₅)L^NMCl₂ (M = Ti (3), Zr (4), Hf (5)) and (η⁵-C₅Me₅)L^NNMCl₂ (M = Ti (7), Zr (8), Hf (9)) were prepared from corresponding (pentamethylcyclopentadienyl)metal trichlorides and the lithium precursors L^NLi and L^NNLi. Besides the desired products a dimeric hafnium compound [(η⁵-C₅Me₅){µ-NC₆H₄-2-(CH₂NMe₂)}HfCl]₂ (10) was also isolated and structurally characterized. The formation of dimeric complexes of this type was also achieved by reacting a series of (η⁵-C₅Me₄R)L^CNMCl₂ (M = Zr, Hf; R = Me, H; L^CN = C₆H₄-2-(CH₂NMe₂)-µ²C,N) complexes with lithium precursors L^NLi and L^NNLi generating [(η⁵-C₅Me₄H){µ-NC₆H₃-2,6-ⁱPr₂}MCl]₂ (M = Zr (11), Hf (13)), [(η⁵-C₅Me₅){µ-NC₆H₃-2,6-ⁱPr₂}MCl]₂ (M = Zr (12), Hf (14)), [(η⁵-C₅Me₄H){µ-NC₆H₄-2-(CH₂NMe₂)-µ²N,N}ZrCl]₂ (15), and [(η⁵-C₅Me₅){µ-NC₆H₄-2-(CH₂NMe₂)}ZrCl]₂ (16), respectively. The formation of 10 by this reaction procedure was not detected; instead monomeric complexes (η⁵-C₅Me₄R)L^NNL^CNHfCl (R = H (17), Me (18)) were observed as major products. NMR and IR spectroscopy techniques and elemental analysis were used for characterization of the prepared complexes, whereas the structures in most cases were determined by X-ray crystallography.