247908-54-9Relevant academic research and scientific papers
Fulvene to cyclopentadienyl conversion with homoleptic complexes of zirconium and hafnium
Rogers, Jonathan S.,Lachicotte, Rene J.,Bazan, Guillermo C.
, p. 3976 - 3980 (2008/10/08)
The reaction of 6,6-dimethylfulvene with M(CH2Ph)4 (M = Zr, Hf) in benzene gives [η5-C5H4(CMe2CH 2Ph)]M(CH2Ph)3 (1, M = Zr; 2, M = Hf) without any observable byproducts. A similar reaction for M = Ti is not observed. The single-crystal X-ray study of 1 shows a three-legged piano-stool geometry with an η2-bound benzyl ligand. A second equivalent of 6,6-dimethylfulvene does not react with either 1 or 2. The bulkier 6,6-diphenyfulvene only reacts cleanly with the more Lewis acidic Hf(CH2Ph)4 to give [η5-C5H4(CPh2CH 2Ph)]Hf(CH2-Ph)3 (3). Using the tetraamido complexes M(NMe2)4 and 6,6-dimethylfulvene, one obtains dimethylamine and [η5-C5H4(CMeCH2)]M(NMe 2)3 (4 for M = Zr) in good yield. These products are formally derived from the deprotonation of a fulvene methyl group and subsequent coordination of the resulting 2-propenylcyclopentadienyl fragment. Reaction of 4 and 6,6-dimethylfulvene affords the bent metallocene [η5-C5H4(CMeCH2)] 2Zr(NMe2)2 (5). Excess 8,8-dimethylbenzofulvene and M(NMe2)4 provides exclusively the product with only one coordinated indene.
