Synthesis and Characterization of Linear Poly(dialkylstannane)s

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• 作者：Fabien Choffat ; Susanne Kä ; ser ; Pascal Wolfer ; Daniel Schmid ; Raffaele Mezzenga ; Paul Smith ; Walter Caseri
• 刊名：Macromolecules
• 出版年：2007
• 出版时间：October 30, 2007
• 年：2007
• 卷：40
• 期：22
• 页码：7878 - 7889
• 全文大小：308K
• 年卷期：v.40,no.22(October 30, 2007)
• ISSN：1520-5835

文摘

A comprehensive study was made of the synthesis of a spectrum of poly(dialkylstannane)s bycatalytic dehydropolymerization of dialkylstannanes (dialkyltin dihydrides, R₂SnH₂, prepared by reduction ofR₂SnCl₂), with R = ethyl, propyl, butyl, pentyl, hexyl, octyl, and dodecyl. The polymerization reactions werefollowed by ¹H and ¹¹⁹Sn NMR spectroscopy, IR spectroscopy (disappearance of the Sn-H vibration), andquantitative measurement of H₂ which evolved during the reaction. Among the numerous metal complexesemployed as catalyst, [RhCl(PPh₃)₃] was found to be particularly suited for the preparation of these inorganicpolymers. The reaction parameters temperature, solvent, R₂SnH₂ concentration, and [RhCl(PPh₃)₃]/R₂SnH₂ ratiowere varied, with the most prominent influence on the monomer conversion being the temperature. The number-average molar masses of the polystannanes were in the range of 1 × 10⁴ to 1 × 10⁵ g/mol, depending on thereaction conditions. For the generic case of the polymerization of Bu₂SnH₂ with [RhCl(PPh₃)₃] as catalyst, it wasdemonstrated that poly(dibutylstannane) did not form by a random polycondensation, but by growth at a rhodiumcomplex, whereby only a minor part of [RhCl(PPh₃)₃] was converted to catalytically active species by reactionwith tin hydrides. The polymers featured phase transitions into liquid-crystalline states, on occasion at remarkablylow temperatures. A particularly high phase transition temperature was observed for poly(dipropylstannane), whichalso was characterized by a high density, indicative of a particularly favorable packing of the propyl groups.