Zirconocene silanolate complexes and their heterogeneous siliceous analogues as catalysts for phenylsilane dehydropolymerization

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• 作者：Vojtech Varga^a ; Michal Horá ; ?ek^b ; Zden¨§k Bastl^b ; Jan Merna^c ; Ivana Cí ; sa?ová ; ^d ; Jan Sý ; kora^e ; Ji?í ; Pinkas^b ; ^{pinkas@jh-inst.cas.cz}
• 关键词：Catalysis ; Dehydrocoupling ; Polysilanes ; Supported metallocenes ; Silanolate ; Silica
• 刊名：Catalysis Today
• 出版年：2012
• 出版时间：5 January 2012
• 年：2012
• 卷：179
• 期：1
• 页码：130-139
• 全文大小：1101 K

文摘

The efficient catalytic dehydropolymerization of phenylsilane by homogeneous zirconocene bissilanolates ([{(c-C₅H₉)₇Si₈O₁₂O}₂Zr(¦Ç⁵-C₅H₅)₂] (1a); [{(c-C₅H₉)₇Si₈O₁₂O}₂Zr(¦Ç⁵-C₅H₄Bu)₂] (1b) [{(c-C₅H₉)₇Si₇O₉(OSiMe₃)O₂}Zr(¦Ç⁵-C₅H₅)₂] (4); [{(Me₃CO)₃SiO}₂Zr(¦Ç⁵-C₅H₅)₂] (5)) and chlorosilanolates ([{(c-C₅H₉)₇Si₈O₁₂O}ZrCl(¦Ç⁵-C₅H₄Bu)₂] (2); ([{(c-C₅H₉)₇Si₇O₉O₃}Zr₂Cl(¦Ç⁵-C₅H₅)₄] (3a); [{(c-C₅H₉)₇Si₇O₉O₃}Zr₂Cl(¦Ç⁵-C₅H₄Bu)₄] (3b)) has been demonstrated. The presence of at least one silanol ligand in the zirconocene moiety was found essential for high catalytic performance. Solid state structure of complex 1a was determined by single crystal X-ray diffraction analysis. A series of nine zirconocene-siliceous catalysts were prepared by grafting of zirconocene moiety onto silica using three general methods: (a) reaction of [(¦Ç⁵-C₅H₅)₂ZrCl₂] with silica in the presence of NEt₃; (b) reaction of [(¦Ç⁵-C₅H₅)₂ZrMe₂] with silica; (c) reaction of solely [(¦Ç⁵-C₅H₅)₂ZrCl₂] with silica. Supported catalysts were characterized by ICP-MS, FT-IR, TGA and selected examples by XPS analysis. Those catalysts prepared by method (a) and (b) were found efficient in the phenylsilane polymerization although a higher Zr/monomer ratio had to be used in comparison with homogeneous analogues. The low concentration of residual silanol groups in supported catalysts was found essential for their high catalytic performance. Advantageous reusability of supported catalysts was demonstrated using SiO₂₍₅₀₀₎/Cp₂ZrCl₂/NEt₃(5.8). The catalytic performance was retained in three consecutive cycles producing polymers with almost identical properties.