Details

Autor(en) / Beteiligte

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

Titel

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

Ist Teil von

• Angewandte Chemie International Edition, 2018-02, Vol.57 (7), p.1821-1825

Auflage

International ed. in English

Ort / Verlag

Germany: Wiley Subscription Services, Inc

Erscheinungsjahr

2018

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• 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. Twist and shout: The structure of gauche‐butadiene has been determined using a combination of sensitive microwave experiments, unambiguously proving its non‐planarity with a twist angle of 34°. High‐level theoretical calculations show that the cis structure is a transition state between the two gauche minima on the potential energy surface (see picture).