On the Structure of Cross-Conjugated 2,3-Diphenylbutadiene

✍ Scribed by Cornelis A. van Walree; Bas C. van der Wiel; Leonardus W. Jenneskens; Martin Lutz; Anthony L. Spek; Remco W. A. Havenith; Joop H. van Lenthe

• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: English
• Weight: 147 KB
• Volume: 2007
• Category: Article
• ISSN: 1434-193X
• DOI: 10.1002/ejoc.200700410

✦ Synopsis

Abstract

The structure of the cross‐conjugated compound 2,3‐diphenylbutadiene was investigated by single‐crystal X‐ray diffraction and computational methods. In the crystal structure the central butadiene fragment adopts an s‐gauche geometry [–55.6(2)° torsion angle φ around the essential single bond], whereas the styrene moieties are close to planarity. MP2/6‐311G* calculations show that the s‐gauche conformation represents the global minimum along the φ coordinate, but also revealed the existence of an s‐trans local minimum. While the crystal structure seems to reflect dominance of styrene‐like conjugation, the MP2/6‐311G* calculations indicate that conjugation in both the styrene and butadiene π‐systems is important. An NBO orbital deletion study shows that the structure is primarily determined by (hyper)conjugation and that steric effects play a minor role. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)