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 (LNH) and 2-[(dimethylamino)methyl]aniline NH2C6H4-2-(CH2NMe2) (LNNH) was investigated. Two series of mononuclear complexes (η5-C5Me5)LNMCl2 (M = Ti (3), Zr (4), Hf (5)) and (η5-C5Me5)LNNMCl2 (M = Ti (7), Zr (8), Hf (9)) were prepared from corresponding (pentamethylcyclopentadienyl)metal trichlorides and the lithium precursors LNLi and LNNLi. 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)LCNMCl2 (M = Zr, Hf; R = Me, H; LCN = C6H4-2-(CH2NMe2)-µ2C,N) complexes with lithium precursors LNLi and LNNLi 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)LNNLCNHfCl (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.