• Devashis Majumdar

      Articles written in Journal of Chemical Sciences

    • Electronegativity of ionic groups. Evaluation from MNDO calculations

      Dipankar Datta Devashis Majumdar

      More Details Abstract Fulltext PDF

      The electronegativities (χG) of some 78 groups/atoms(G) including some 11 ionic ones have been evaluated from the charge on the H atom in the corresponding H−G molecules. The charges are determined by the MNDO method of Dewar at the optimised geometries. For some 38 molecules/ions whereab initio molecular orbital calculations are available, a reasonable linearity (correlation coefficientr=0·900) has been observed between the MNDO charges and the charges obtained at the 6–31G*//6–31G* level. The very good linear correlation (r=0·950) obtained between the χG values and Inamoto’s i scale for some 72 groups/atoms including some 8 monocationic groups shows that the method works quite well for the monocationic groups. However the anionic groups probably cannot be tackled in the present approach. The1Jcc (ortho-ipso) coupling constants in mono-substituted benzenes also correlate linearly with the χG values for some 33 groups/atoms to a satisfactory extent (r=0·917). It is mentioned that there does not exist a proper theoretical scale for group electronegativity which can accommodate ionic and neutral groups on a uniform basis.

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