TY - JOUR
T1 - The Molecular Structure of gauche-1,3-Butadiene
T2 - Experimental Establishment of Non-planarity
AU - Baraban, Joshua H.
AU - Martin-Drumel, Marie Aline
AU - Changala, P. Bryan
AU - Eibenberger, Sandra
AU - Nava, Matthew
AU - Patterson, David
AU - Stanton, John F.
AU - Ellison, G. Barney
AU - McCarthy, Michael C.
N1 - Publisher Copyright:
© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
PY - 2018/2/12
Y1 - 2018/2/12
N2 - 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.
AB - 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.
KW - ab initio calculations
KW - butadiene
KW - conjugation
KW - molecular dynamics
KW - rotational spectroscopy
UR - http://www.scopus.com/inward/record.url?scp=85040709767&partnerID=8YFLogxK
U2 - 10.1002/anie.201709966
DO - 10.1002/anie.201709966
M3 - Article
AN - SCOPUS:85040709767
SN - 1433-7851
VL - 57
SP - 1821
EP - 1825
JO - Angewandte Chemie - International Edition
JF - Angewandte Chemie - International Edition
IS - 7
ER -