Alkyl exchange between aluminum trialkyls and zirconocene dichloride complexes - a measure of electron densities at the Zr center

被引:47
作者
Beck, S [1 ]
Brintzinger, HH [1 ]
机构
[1] Univ Konstanz, Fak Chem, D-78464 Constance, Germany
关键词
zirconocenes; electron density; aluminum alkyls; methyl transfer;
D O I
10.1016/S0020-1693(97)05871-4
中图分类号
O61 [无机化学];
学科分类号
070301 ; 081704 ;
摘要
Equilibrium constants have been determined for the formation of 15 different zirconocene monomethyl monochloro complexes from the respective dichloride complexes and Al-2(CH3)(6). The results indicate chat the tendency of a particular zirconocene complex to exchange a chloride against a methyl ligand is a measure for the electron deficiency at its Zr center. The results indicate particularly low electron densities for complexes with indenyl instead of cyclopentadienyl ligands, especially for those containing a dimethylsilyl bridge. Only one methyl group is transferred to a zirconocene dichloride even by a large excess of Al-2(CH3)(6), while the uptake of two alkyl groups, followed by alkane evolution, is observed with triethyl and triisobutyl aluminum. (C) 1998 Elsevier Science S.A.
引用
收藏
页码:376 / 381
页数:6
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