| 摘要 |
Bridged metallocenes of group IVb metals provide improved results when the bridge comprises a neutral electron-donor substituent of general formula R''' Z R''''j wherein - R''' is a rigid unsaturated hydrocarbon radical between Z and the bridge, such that Z is separated from the bridge by 2 to 3 carbon atoms - Z is nitrogen, phosphorus, oxygen or sulphur, - R'''' is H or an alkyl, cycloalkyl, aryl, alkylaryl or arylalkyl having a maximum of 15 carbon atoms, each R'''' being the same or different, - j is 1 when Z = O or S and 2 when Z = N or P, |
