J(C 13-H) spin-spin coupling constants of several unsaturated hydrocarbons calculated by the maximum overlap method

Abstract

The hybrids for 3,3-dimethylcyclopropene (I), 1,3,3-trimethylcyclopropene (II), isobutylene (III). 1,1-dimethylallene (IV), and tetramethylallene (V) have been calculated by the maximum overlap method. The obtained hybrid coefficients were used to calculate J(C 13-H) coupling constants using the Muller-Pritchard relationship (1) and also the modified expression (2) suggested by Maksić, Eckert-Maksić and Randić. The calculated spin-spin coupling constant values were compared with the experimental data. The values obtained with (2) are superior to those obtained with (1). Thus, for example, for the olefinic part of I the following values were obtained: 190·9 cps and 208·3 cps by (1) and (2), respectively, as compared with the experimental value of 220 cps.