RESTRICTED ROTATION ABOUT NSP(2)-CSP(3) BOND THROUGH PI-ELECTRONIC INTERACTIONS - A H-1-NMR STUDY

The electronic repulsion of a carboxyl group from a phenyl ring has be en found to restrict relation about Nsp(2)-Csp(3) bond. A stable sp(3) -geometry of a carbon in N-CHR-COOH derivatives of a,beta(9,10-dihydro anthracene-9,10-diyl)succinimde has been demonstrated on the basis of shielding parameters of N'-alkyls. The carboxyl group does not exhibit hydrogen bonding with the carbonyls of the succinimide and remains in anti orientation. Though the anisotropic effect of an olefinic bond i s fairly small, the interaction of carboxyl group with the olefinic bo nd is evident in CPD-MA adduct derivative.