The Molecular Structure of gauche-1,3-Butadiene: Experimental Establishment of Non-planarity

Joshua H. Baraban, Marie Aline Martin-Drumel, P. Bryan Changala, Sandra Eibenberger, Matthew Nava, David Patterson, John F. Stanton, G. Barney Ellison, Michael C. McCarthy

Research output: Contribution to journalArticlepeer-review

37 Scopus citations

Abstract

The planarity of the second stable conformer of 1,3-butadiene, the archetypal diene for the Diels–Alder reaction in which a planar conjugated diene and a dienophile combine to form a ring, is not established. The most recent high level calculations predicted the species to adopt a twisted, gauche structure owing to steric interactions between the inner terminal hydrogens rather than a planar, cis structure favored by the conjugation of the double bonds. The structure cis-1,3-butadiene is unambiguously confirmed experimentally to indeed be gauche with a substantial dihedral angle of 34°, in excellent agreement with theory. Observation of two tunneling components indicates that the molecule undergoes facile interconversion between two equivalent enantiomeric forms. Comparison of experimentally determined structures for gauche- and trans-butadiene provides an opportunity to examine the effects of conjugation and steric interactions.

Original languageEnglish
Pages (from-to)1821-1825
Number of pages5
JournalAngewandte Chemie - International Edition
Volume57
Issue number7
DOIs
StatePublished - 12 Feb 2018

Keywords

  • ab initio calculations
  • butadiene
  • conjugation
  • molecular dynamics
  • rotational spectroscopy

ASJC Scopus subject areas

  • Catalysis
  • Chemistry (all)

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