Synthetic and NMR Studies of Neutral and Cationic Dinuclear Fulvalene Zirconium Complexes Containing the “Zr<sub>2</sub>(μ-CN<sup>t</sup>Bu)” Unit
作者:Eva Royo、Mikhail Galakhov、Pascual Royo、Tomás Cuenca
DOI:10.1021/om000240n
日期:2000.8.1
Methylation of the previously. described isocyanide-bridged complex [Zr(eta(5)-C5H5)Cl}(2)(mu-(CNBu)-Bu-t)(mu-eta(5)-C5H4-eta(5)-C5H4)] with 2 equiv of MgClMe in toluene at 80 degrees C afforded the dinuclear dimethyl complex [Zr(eta(5)-C5H5)(CH3}(2)(mu-(CNBu)-Bu-t)(mu-eta 5-C5H4)]. The same reaction with I or 2 equiv of MgClMe at room temperature gave a mixture of compounds containing the dimethyl derivative 1 and two isomers of the monomethyl derivative [Zr(eta(5)-C5H5)}(2)-(CH3)(Cl)(mu-(CNBu)-Bu-t)(mu-eta(5)-C5H4-eta(5)-C5H4)], 2a, 2b, identified by NMR spectroscopy. Analogous methylation of the related compound [Zr(eta(5)-1,3-(Bu2C5H3)-Bu-t)Cl}(2)(mu-(CNBu)-Bu-t)(mu-eta(5)-C5H4-eta(5)-C5H4)], isolated by reaction of the zirconium(III) derivative [Zr(eta(5)-1,3-(Bu2C5H3)-Bu-t)(mu-Cl)}(2)(mu-eta(5)-C5H4-eta(5)-C5H4)] With 1 equiv of (CNBu)-Bu-t in toluene, gave a mixture of unidentified compounds. Treatment of the dimethyl complex [Zr(eta(5)-C5H5)(CH3)}(2)(mu-(CNBu)-Bu-t)(mu-eta(5)-C5H4)] 1, with 1 equiv of the Lewis acid B(C6F5)(3) in dichloromethane at -78 degrees C affords the new yellow crystalline zirconium cationic derivative [Zr(eta(5)-C5H5)}(2)(mu-CH3)(mu-(CNBu)-Bu-t)(mu-eta(5)][BMe(C6F5)(3)], 4. Hydrolysis of the mu-methyl compound 4 led to the mu-hydroxo cationic derivative [Zr(eta(5)-C5H5)}(2)(mu-OH)(mu-(CNBu)-Bu-t)(mu-eta(5)-C5H4-eta(5)-C5H4)][BMe(C6F5)(3)], 5. Compound 4 reacts with an excess of isocyanides CNR in dichloromethane at -78 degrees C to give the cationic species [Zr(eta(5)-C5H5)}(2)(CH3)(CNR)(mu-CNR)(mu-eta(5)-C5H4)][BMe(C6F5)(3)] (R = Bu-t, 6;2,6-Me2C6H3, 7). All of the reported compounds were characterized by the usual analytical and NMR spectroscopic methods, which are discussed.