[(NHC)CrCl(mu-Cl)(THF)](2) and (NHC)(2)CrCl2 (NHC=1,3-Diisopropyl-4,5-dimethylimidazole-2-ylidene): Syntheses, Structures, and Polymerization Activities
- 化学化工－已发表论文 
The preparation of divalent chromium N-heterocyclic carbene (NHC, 1,3-diisopropyl-4,5-dimethylimidazole-2-ylidene) compounds is reported. The reaction of 1:1 molar ratio of NHC with CrCl2 led to an isolation of [(NHC)CrCl(mu-Cl)(THF)](2) (1), while that of 2:1 ratio resulted in the formation of (NHC)(2)CrCl2 (2). 1 can be considered as an intermediate in the formation of 2 and further converted into 2 by the addition of another equiv. of NHC. The reaction of 2 with CpNa afforded an ion pair compound [(NHC)(2)CrCp](+)[Cp](-) (3), indicating a strong coordination ability of NHC supplanting one of the ionic Cr-Cp bonding. In combination of methylalumoxane (MAO) as cocatalyst 1 and 2 both are active for catalyzing ethylene polymerization.