| 摘要 |
Compounds having one of the general formulae: <CHEM> wherein: M is a metal; Z is selected from the group consisting of oxygen, sulphur, NR"" and PR""; R", R"' and R"" are each a radical independently selected from hydrogen, C1-6 alkyl, C3-8 cycloalkyl, aryl and heteroaryl, or R" and R"' together form an aryl or heteroaryl radical, each said radical being optionally substituted; R' is either as defined for R", R"' and R"" when included in a compound having the general formula (IA) or, when included in a compound having the general formula (IB), is selected from hydrogen, C1-6 alkylene and C3-8 cycloalkylene, the said alkylene and cycloalkylene group being optionally substituted; R1 is a constraint steric hindrance group having a pKa of at least about 15; R2 is an anionic ligand; R3 and R4 are each hydrogen or a radical selected from, among others, C1-20 alkyl, C1-20 alkenyl; R3 and R4 together may form a fused aromatic ring system, and y represents the number of sp2 carbon atoms between M and the carbon atom bearing R3 and R4 and is an integer from 0 to 3 inclusive are useful as catalysts for olefin metathesis and atom transfer radical polymerization. <IMAGE>
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