SOME HAZARDS OF ELECTRONEGATIVITY CORRELATIONS

The linear correlations of enthalpy of formation differences with elec tronegativity (covalent potential, V-x), published by Luo and Benson ( LB), have been reexamined with inclusion of additional data for silico n and other group 14 organometallic compounds, While there is support for the idea that the covalent potential represents a good scale for s uch correlations, certain conclusions of LB are not supported. The cor relations yield the following Delta H-f(0) values (kT mol(-1)): SiH3I, +8.6; Me3SiF, -586; Me3SiNH2, -291; Me3SiSH, -273, in close agreement with LB. However, there is no case for revision of Delta H-f(0)(Si2H6 ) = 80.0 kJ mol(-1) and our estimated Delta H-f(0) values (kJ mol(-1)) , for MeGeH3 (42 +/- 4) and MeSnH3 (118 +/- 4) do not fit the linear c orrelations previously proposed. It is shown that average hydrogen-for -methyl substitution enthalpies fit best a nonlinear correlation with V-x, just as shown earlier by Benson and co-workers for the same corre lation with Pauling electronegativity.