198766-46-0Relevant academic research and scientific papers
Dinuclear cationic zirconium complexes with the fulvalene ligand. Synthesis and reactivity
Cuenca, Tomas,Galakhov, Mikhail,Jimenez, Gerardo,Royo, Eva,Royo, Pascual,Bochmann, Manfred
, p. 209 - 215 (1997)
The reaction of B(C6F5)3 with the tetramethyl zirconium fulvalene derivative [Zr(C5H5)(CH3)2]2(μ-η5:η5-C10H8) 1a in CH2Cl2 at -60°C gives the cationic compound [{Zr(C5H5)}2(η-CH3)(μ-CH2)(μ-η5:η5-C10H8)]+[BMe(C6F5)3]- 2a. A similar reaction using the 1,3-di(tert-butyl) cyclopentadienyl derivative [Zr(1,3-tBu2-C5H3)(CH3)2]2(μ,-η5:η5-C10H8) 1b affords a mixture of compounds, none of them being isolable as pure substances. However, monitoring the reaction of B(C6F5)3 with 1b by variable temperature NMR spectroscopy, between -80°C and 25°C, permits the observation, at low temperature, of the intermediate dimethyl μ-methyl cationic species [{Zr(1,3-tBu2-C5H3)(CH3)}2(μ-CH3)(μ-η5-η5-C10H8)]+ 8b which decomposes with evolution of methane to give the μ-methylene, μ-methyl complex [{Zr(1,3-tBu2-C5H3)}2(μ-CH3)(μ-CH2)(μ-η5:η5-C10H8)]+[BMe(C6F5)3]- 2b. In dichloromethane or chloroform complexes 2a and 2b undergo slow conversion to the μ-chloro, μ-methylene derivatives [{ZrCp′}2(μ-Cl)(μ-CH2)(μ-η5:η5-C10H8)]+[BMe(C6F5)3]- (Cp′ = C5H5 3a, 1,3-tBu2-C5H3 3b) by a halide abstraction process. Prolonged exposure of 3b to chlorocarbons gives the dichloro μ-chloro compound [{Zr(1,3-tBu2-C5H3)Cl}2(μ-Cl)(μ-η5:η5-C10H8)]+[BMe(C6F5)3]- 9b. The addition of an excess of donor ligands to a solution of 2a in dichloromethane-d2 at -60°C affords the cationic adducts [{Zr(C5H5)}2(CH3)L(μ-CH2)(μ-η5:η5-C10H8)]+[BMe(C6F5)3]-[L = PMe3 (4a), PMe2Ph (5a), PPh3 (6a), THF (7a)] obtained as a mixture of syn-and anti-isomers. The compound 5a can be isolated as an analytically pure sample when this reaction is carried out in CH2Cl2.
