A Quantitative Analysis of ￥e-Nobonded and Through-Bond Interactions in n-Butane, n-Buthyl Radical and Tetramethylene Diradical

摘要

A quantitative treatment of ヰ-nonbonded and n-ヲ* interactions and through-bond coupling effect was attempted using n-butane, n-butyl radical, and tetramethylene diradical. Results of STO-3G level calculations showed that: (1) conformational preferences can be predicted quantitatively based solely on the additive effect of ヰ-nonbonded and n-ヲ* interactions, the predominant effect being the ヰ-nonbonded interactions, (2) (n-ヲ*)anti is destabilizing whereas (n-ヲ*)syn is weakly stabilizing, which are contrary to what we expect from the normal n-ヲ* interaction, (3) througb-bond coupling of the two radical lobes is destabilizing for the triplet but stabilizing for the singlet tetramethylene diradical.