Role of delocalization in benzene

Journal Article · Wed Nov 17 04:00:00 EST 1993 · Journal of the American Chemical Society; (United States)

DOI:https://doi.org/10.1021/ja00076a061· OSTI ID:7301863

Glendening, E D; Faust, R; Streitwieser, A; Vollhardt, K P.C. ^[1]; Weinbold, F ^[2]

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1. Univ. of California, Berkeley, CA (United States) Lawrence Berkeley Lab., CA (United States)
2. Univ. of Wisconsin, Madison, WI (United States)

The influence of [pi] delocalization on the geometry of benzene is examined at the ab initio SCF level of theory. We find that benzene favors a bond alternating geometry when its canonical [pi] MOs are replaced by three localized ethylenic orbitals, revealing that delocalization is in part responsible for the equilibrium symmetric structure. In apparent contrast, a [sigma]-[pi] energy partitioning analysis suggests that the benzene [sigma] framework is responsible for the symmetric structure, the [pi] system preferring a distorted geometry. Shaik et al. have therefore concluded that delocalization in not an important symmetrizing force in this molecule. We show, however, that the [pi] energy component contains a sizable and strongly geometry dependent contribution from the localized (Kekule) wave function. Thus, it appears to be misleading to judge the nature of delocalization based on a [sigma]-[pi] partition. We conclude that delocalization effects act to strongly stabilize symmetric benzene in essential accord with the concepts of classical resonance theory. 27 refs., 6 figs., 2 tabs.

• DOE Contract Number: AC03-76SF00098
• OSTI ID: 7301863
• Journal Information: Journal of the American Chemical Society; (United States), Journal Name: Journal of the American Chemical Society; (United States) Vol. 115:23; ISSN JACSAT; ISSN 0002-7863
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
99 GENERAL AND MISCELLANEOUS
990200 -- Mathematics & Computers
AROMATICS
BENZENE
CALCULATION METHODS
CHEMICAL BONDS
CONFIGURATION
DATA
ELECTRONIC STRUCTURE
HYDROCARBONS
INFORMATION
MATHEMATICAL MODELS
MOLECULAR ORBITAL METHOD
NUMERICAL DATA
ORGANIC COMPOUNDS
THEORETICAL DATA