Irregular cyclization reactions in titanocenes bearing pendant double bonds |
| |
Institution: | a J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejškova 3, 182 23 Prague 8, Czech Republic b Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 2030, 128 40 Prague 2, Czech Republic |
| |
Abstract: | Reduction of methyl-substituted titanocene dichlorides bearing pendant double bonds TiCl2{η5-C5Me4(CH2CMeCH2)}2] (1) and TiCl2{η5-C5Me4(SiMe2(CH2)2CHCH2)}2] (2) with magnesium yielded diamagnetic Ti(IV) compound Ti{η1:η1:η5-C5Me3(CH2)(CH2CH(Me)CH2)}{η5-C5Me4(CH2C(Me)CH2)}] (4) and paramagnetic Ti(III) compound Ti{η5-C5Me4(SiMe2CH2CHCHMe)}(μ-η3,η1:η5,η1(Ti:Mg){C5Me3(CH2)(SiMe2CHCHCMe)})Mg(OC4H8)2] (6), respectively. The reluctance of titanocene intermediates to undergo intramolecular cyclization to cyclopentadienyl-ring-tethered titanacycles (as typically observed) can be explained by a shortness of the 2-methylallyl group and steric hindrance of its double bond in the former case and, in the latter case, by an attack of magnesium on the titanocene intermediate, faster than cyclization reactions. The crystal structures of 4 and 6 were determined by single-crystal X-ray diffraction. |
| |
Keywords: | Titanium Magnesium Titanocene Pendant double bonds C-H activation Heterobinuclear complex X-ray crystallography |
本文献已被 ScienceDirect 等数据库收录! |
|