The 'H, 13C and 77Se chemical shifts and the 'aC(Me)H(Me)l, "*J(SeC) and *J(SeH) coupling constanis in 14 paraor meta-substituted selenoauisoles, R-C6H.,+CH3, have been measured and the dependence of these parameters on the electronic effects of the substituent R is discussed. A signiscant (up to 6ppm) deviation from additivity of the substituent influence on the shielding of the 13C ring carbons has been found.
The electronic and geometric structural changes of acetone upon protonation are studied by 3C NMR spectroscopy and by molecular orbital (MO) calculations using the LORG (local orbital/local origin) method to calculate chemical shieldings and the CLOPPA (contributions for localized orbitals within the polarised propagator approach) analysis of the J coupling constants. In protonated acetone the 13C NMR spectrum has been resolved and two different methyl resonances (1.2 ppm apart) have been assigned. The one-bond C-C coupling constants
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