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 language | American English |
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Pages (from-to) | 1821-1825 |
Number of pages | 5 |
Journal | Angewandte Chemie - International Edition |
Volume | 57 |
Issue number | 7 |
DOIs | |
State | Published - 12 Feb 2018 |
Keywords
- ab initio calculations
- butadiene
- conjugation
- molecular dynamics
- rotational spectroscopy
All Science Journal Classification (ASJC) codes
- General Chemistry
- Catalysis