two electrons. The C1 symmetric dialkyltungsten complexes were heated to 30–60 °C to generate alkylidene species. The substituent effects of the ligands on the catalytic behavior for the ring-opening metathesis polymerization of norbornene derivatives were studied. cis-Contents of the poly(norbornene)s were controlled by the steric effect of alkyne and aryloxo ligands in these dialkyl complexes. The
Dichlorotungsten络合物,W(η 2 -EtCCEt)(ME 2
TBP)
氯2(ME 2
TBP = 2,2'-
硫代双(4,6- dimethylphenoxo))和W(η 2 -EtCCEt)(吨将Bu 2
TBP)Cl 2(t Bu 2
TBP = 2,2'-
硫代双(4-甲基-6-
叔丁基苯氧基))与Mg(CH 2 SiMe 3)2反应,得到相应的C s-二烷基络合物,ç小号-W(η 2 -EtCCEt)(ME 2
TBP)(CH 2森达3)2(1 - c ^小号)和Ç小号-W(η 2 -EtCCEt)(吨卜2
TBP)(CH 2森达3)2(2 - ç小号)。这些Ç小号对称dialkyltungsten络合物1 - c ^小号和2 - ç小号发现经历立体异构化成Ç 1分对称异构体,1 - c ^ 1和2 - ç1,在30°C下。估计了从1 - C s到1 - C 1