Hybridisation in benzene valence isomers by the method of maximum overlap

Abstract

Hybridisation in valence isomers of benzene: ‘ Dewar ’ benzene, benzvalene, and prismane, is considered by the method of maximum overlap. All these molecules are highly strained as evidenced by a larger p-content of the hybrids involved in C–C bonds. The calculated exponents n of spⁿ-hybrids for C–H bonds correlate with n.m.r. chemical shifts of the protons. A linear relationship τ= 5(n– 1) represents the experimental data quite well. An exception is found in molecules containing three-membered rings, which show a considerable deviation from the above relationship. Other factors beyond the nearest carbon atom influence are responsible for these deviations.