Isolation and Structure of [HC{CH(SiMe3)(SnMe3)}2]+: A Remarkably Stable sec-Alkyl Cation

Schormann, Mark, Garratt, Shaun, Hughes, David L., Green, Jennifer C. and Bochmann, Manfred ORCID: (2002) Isolation and Structure of [HC{CH(SiMe3)(SnMe3)}2]+: A Remarkably Stable sec-Alkyl Cation. Journal of the American Chemical Society, 124 (38). pp. 11266-11267. ISSN 0002-7863

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The reaction of the tin-substituted propene Me3Sn(R)CHCH==CHR (R = SiMe3) with MCl4 in dichloromethane in the presence of Me3SnCl gives the first examples of isolable sec-alkyl carbocation salts, [HC{CH(R)SnMe3}2]+M2Cl9- (M = Zr, Hf). The compounds are thermally stable and, unlike previously isolated trialkyl carbocations, do not require superacidic media or weakly coordinating anions for stability. The crystal structure and DFT calculations suggest polarization of the Sn substituents and hyperconjugation as the reason for the unexpected stability. The stabilizing effect of tin is significantly stronger than that of Si. The carbocations are effective initiators for the polymerization of isobutene, isoprene, and a-methylstyrene.

Item Type: Article
Faculty \ School: Faculty of Science > School of Chemistry
Depositing User: Rachel Smith
Date Deposited: 02 Nov 2010 17:48
Last Modified: 24 Oct 2022 03:25
DOI: 10.1021/ja026443f

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