| 摘要 |
The cpds. are : (where M is Cg. IV transition metal; R1-R5 are H or a substituent; n is 0-3 such that when M is Ti and when n is 0, R1-R5 do not all represent H; L is an anionic ligand; L1 is a neutral liqand and m is 0-2). Examples of (i) are tetrakis(benzy)zirconium (or hafnium), etc. They are used as initiators for polymerisation of unsatd. monomers (olefins, butadiene, etc.). The cpds. are prepd. by reaction of an organometallic cpd. of a Gp. I-III element (Grignard reagent) with the tetrahalide of a Gp. IV metal
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