| Abstract: | MNDO calculations on n]metacyclophanes and a variety of related compounds are reported. An analysis of the strain, imposed by the oligomethylene bridge, and its distribution over the distorted benzene ring and the oligomethylene bridge is presented. The effect of strain and bending of the benzene ring on aromatic delocalization is investigated by a comparison of ΔHof of the bent benzene systems with that of a correspondingly bent, but localized 1,3,5-cyclohexatriene. The results indicate that, even in the case of the highly bent 4]metacyclophane ( 1a ), localization is unfavorable by about 10 kcal/mol. |
