Mechanism and kinetics of sigmatropic rearrangements in cyclononatetraenyl(trimethyl)tin

Ilya Gridnev, Peter R. Schreiner, Oleg L. Tok, Yuri N. Bubnov

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

The dynamic behavior of cyclononatetraenyl(trimethyl)tin (3) was analyzed in detail by a combination of dynamic NMR techniques and high-level, ab initio, density functional calculations {Becke3-Lee-Yang-Parr (B3LYP) in conjunction with 6-31G* (C and H) and 3-21G* (Sn) basis sets for optimizations as well as 6-311G* (C and H) and 3-21G* (Sn) basis sets for single-point energy evaluations on the optimized geometries}. Complete 1H and 13C NMR spectra of 3 were assigned at 173 K; a comparison of computed and measured NMR data was used to elucidate the peak assignments of the endo ground-state structure of 3. 2D 13C, 13C-EXSY experiments in the temperature range 173-195 K provide strong evidence for [1,9]-SnMe3 migrations in 3. The experimental activation energy for this process (25.1 ± 2.5 kJ mol-1), obtained from a series of 2D EXSY spectra, is in excellent agreement with the computed value (26.4 kJ mol-1). The analysis of the selectivities of sigmatropic migrations in a series of cycloheptatrienyl and cyclononatetraenyl derivatives of boron and tin suggests that orbital control is the dominant factor governing the selectivities and mechanisms of these rearrangements. If several nearly degenerate migrations are possible, the least-motion principle favors the rearrangement which involves minimal motion of the migrating group. Hence, the barrier of a particular migration is determined by the properties of the carbon cycle rather than by the nature of migrating group.

Original languageEnglish
Pages (from-to)2828-2835
Number of pages8
JournalChemistry - A European Journal
Volume5
Issue number10
DOIs
Publication statusPublished - 1999 Jan 1
Externally publishedYes

Keywords

  • Density functional calculations
  • Least-motion principle
  • NMR spectroscopy
  • Sigmatropic migrations
  • Tin

ASJC Scopus subject areas

  • Catalysis
  • Organic Chemistry

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