Reactivity of the [(η5-C5Me5)TiCH3][RB(C6F5)3] Complexes Identified as Active Species in Syndiospecific Styrene Polymerization
Reactivity of the [(η5-C5Me5)TiCH3][RB(C6F5)3] Complexes Identified as Active Species in Syndiospecific Styrene Polymerization
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[(η5-C5Me5)TiCH3][RB(C6F5)3]配合物的反应活性被鉴定为间规苯乙烯聚合中的活性物质
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发表时间：
1998
期刊：
影响因子：
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通讯作者：
F. Laschi
中科院分区：
文献类型：
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作者：
A. Grassi;S. Saccheo;A. Zambelli;F. Laschi
用ESR波谱研究了烷基配合物[Cp*Ti（III）（CH 3）][RB（C6 F5）3]（Cp* = η5-C5 Me 5; R = CH 3，− C6 F5）与富含α-13 C的对氯苯乙烯的反应性，以了解“半茂钛”催化剂促进苯乙烯和取代苯乙烯间规聚合中活性物种的化学结构.在聚合条件下，对氯苯乙烯在Ti（III）−烷基键中的二级（2，1）聚插入被观察到。Cp*TiIIIR+配合物在苯乙烯间规聚合中的作用已被最终证实。此外，还用ESR波谱研究了富13 C配合物[Cp*Ti（13 CH 3）][RB（C6 F5）3]与PMe 3和Al（13 CH 3）3的反应。PMe 3从Cp* Ti 13 CH 3（μ-13 CH 3）B（C6 F 5）3离子对的配位层中置换甲基硼酸根阴离子，生成相应的膦加合物Cp*Ti（CH 3）（PMe 3）2+。以同样的方式，[Cp*Ti（13 CH 3）][B（C6 F5）4]与Al（13 CH 3）3.
The reactivity of the alkyl complexes [Cp*Ti(III)(CH3)][RB(C6F5)3] (Cp* = η5-C5Me5; R = CH3, −C6F5) with α-13C-enriched p-chlorostyrene has been investigated by means of ESR spectroscopy in order to gain insight into the chemical structure of the active species in syndiospecific polymerization of styrene and substituted styrenes promoted by “half-titanocene”-based catalysts. Secondary (2,1) polyinsertion of p-chlorostyrene into a Ti(III)−alkyl bond has been observed under polymerization conditions. The role of Cp*TiIIIR+ complexes in syndiospecific styrene polymerization has conclusively been confirmed. Furthermore, the reaction of the 13C-enriched complex [Cp*Ti(13CH3)][RB(C6F5)3] with PMe3 and Al(13CH3)3 has also been investigated by ESR spectroscopy. PMe3 displaces the methylborate anion from the coordination sphere of the Cp*Ti13CH3(μ-13CH3)B(C6F5)3 ion pair and produces the corresponding phosphine adduct Cp*Ti(CH3)(PMe3)2+. In the same manner, the reaction of [Cp*Ti(13CH3)][B(C6F5)4] with Al(13CH3)3 ...