fulltext.study @t Gmail

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

Paper ID Volume ID Publish Year Pages File Format Full-Text
55622 47059 2012 10 PDF Available
Title
Zirconocene silanolate complexes and their heterogeneous siliceous analogues as catalysts for phenylsilane dehydropolymerization
Abstract

The efficient catalytic dehydropolymerization of phenylsilane by homogeneous zirconocene bissilanolates ([{(c-C5H9)7Si8O12O}2Zr(η5-C5H5)2] (1a); [{(c-C5H9)7Si8O12O}2Zr(η5-C5H4Bu)2] (1b) [{(c-C5H9)7Si7O9(OSiMe3)O2}Zr(η5-C5H5)2] (4); [{(Me3CO)3SiO}2Zr(η5-C5H5)2] (5)) and chlorosilanolates ([{(c-C5H9)7Si8O12O}ZrCl(η5-C5H4Bu)2] (2); ([{(c-C5H9)7Si7O9O3}Zr2Cl(η5-C5H5)4] (3a); [{(c-C5H9)7Si7O9O3}Zr2Cl(η5-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 [(η5-C5H5)2ZrCl2] with silica in the presence of NEt3; (b) reaction of [(η5-C5H5)2ZrMe2] with silica; (c) reaction of solely [(η5-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.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (109 K)Download as PowerPoint slideHighlights► Zirconocene bissilanolates and chlorosilanolates are active in phenylsilane dehydropolymerization. ► The presence of at least one silanol ligand in the zirconocene moiety is essential for high catalytic performance. ► Grafting of zirconocene on silica surface results in materials with Zr loading 0.8–9.5 wt%. ► Supported complexes catalyze phenylsilane dehydropolymerization. ► SiO2(500)/Cp2ZrCl2/NEt3(5.8) and SiO2(200)/Cp2ZrCl2/NEt3(7.8) behave as recyclable catalysts.

Keywords
Catalysis; Dehydrocoupling; Polysilanes; Supported metallocenes; Silanolate; Silica
First Page Preview
Zirconocene silanolate complexes and their heterogeneous siliceous analogues as catalysts for phenylsilane dehydropolymerization
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us
Publisher
Database: Elsevier - ScienceDirect
Journal: Catalysis Today - Volume 179, Issue 1, 5 January 2012, Pages 130–139
Authors
, , , , , , ,
Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us