Cyclopentadienyl and Olefin Substituent Effects on Insertion and β-Hydrogen Elimination with Group 4 Metallocenes. Kinetics, Mechanism, and Thermodynamics for Zirconocene and Hafnocene Alkyl Hydride Derivatives
作者:Paul J. Chirik、John E. Bercaw
DOI:10.1021/om0580351
日期:2005.10.1
(RnCp)2MH2 (RnCp = alkyl-substituted cyclopentadienyl; M = Zr, Hf), with olefins afford stable metallocene alkyl hydride complexes of the general formula (RnCp)2M(CH2CHR‘2)(H) (R‘ = H, alkyl). For sterically crowded, monomeric dihydrides, Cp*2ZrH2 (Cp* = η5-C5Me5), Cp*(η5-C5Me4H)ZrH2, Cp*(η5-C5Me4Et)ZrH2, Cp*2HfH2, and Cp*(η5-C5H3-1,3-(CMe3)2)HfH2, second-order rate constants for olefin insertion have been
第4族金属茂二氢化物(R n Cp)2 MH 2(R n Cp =烷基取代的环戊二烯基; M = Zr,Hf)与烯烃的反应提供了稳定的通式(R n Cp)2的金属茂烷基氢化物配合物M(CH 2 CHR ' 2)(H)(R'= H,烷基)。对于空间位拥挤,单体dihydrides中,Cp * 2 ZRH 2(CP * =η 5 -C 5我5)中,Cp *(η 5 -C 5我4 1H)ZRH 2中,Cp *(η 5 -C 5我4 ET)ZRH 2中,Cp * 2 HFH 2,1和Cp *(η 5 -C 5 H ^ 3 -1,3-(CME 3)2)HFH 2的用于烯烃插入二阶速率常数已被测量。对于Cp * 2 HfH 2,发现烯烃的相对插入率是1-戊烯>苯乙烯≫顺式2-丁烯>环戊烯>反式2-丁烯>异丁烯。异丁烯插入的Cp *(η率5 -C 5我4 1H)ZRH 2是3.8×10 3-Cr * 2