606936-97-4Relevant academic research and scientific papers
Synthesis, Characterization, and Reactions of a Half-Metallocene Benzylidene Complex of Tantalum Bearing 2,3-Dimethyl-1,3-butadiene and Pentamethylcyclopentadienyl Ligands
Mashima, Kazushi,Yonekura, Hirotaka,Yamagata, Tsuneaki,Tani, Kazuhide
, p. 3766 - 3772 (2003)
A half-metallocene benzylidene complex of tantalum, Ta(CHPh)Cp*(η4-supine-2,3-dimethyl-1,3-butadiene) (1), was prepared by treating TaCl2Cp*(η 4-supine-2,3-dimethyl-1,3-butadiene) (2) with Mg(CH 2Ph)2 in toluene. The structure of 1 was determined by X-ray analysis, indicating the syn rotamer of the Ta=CHPh moiety; the Ph group points upward toward the Cp* ligand. The coordinatively unsaturated 16-electron complex 1 reacted with some unsaturated organic molecules (ethylene, cyclopentene, and tert-butyl cyanide), an alcohol, and an amine. The cycloaddition of ethylene and cyclopentene gave rise to metallacyclobutanes. The addition of tert-butyl cyanide to 1 afforded an imido tantalum complex, Ta(NC-(tBu)=CHPh)Cp*(η 4-supine-2,3-dimethyl-1,3-butadiene) (6), which was derived from the metathesis reaction of a nascent 2-aza-1-tantalacyclobut-2-ene intermediate. Protonolysis of 1 by addition of methanol and p-methoxyaniline gave a methoxy benzyl complex, Ta(CH2Ph)(OCH3)Cp*(η 4-supine-2,3-dimethyl-1,3-butadiene) (7), and an amido benzyl complex, Ta(CH2Ph)(NHC6H4OCH 3)Cp*(η4-supine-2,3-dimethyl-1,3-butadiene) (8), respectively. Upon heating at 60 °C, complex 8 was converted to an imido butenyl complex, Ta(CH2Ph)(NC6H4-OCH 3)(η1-2,3-dimethyl-2-butene)Cp* (9). Structures of the amido complex 8 and the imido complexes 6 and 9 were determined by X-ray analysis.
