Electronegativity bond length corrections table

A number of empirical methods exist for the adjustment of covalent bond lengths for ionic effects.34,35 These are based primarily on formulas that involve the sum of the covalent radii corrected by a factor that is dependent on the electronegativity difference between the atoms. In many instances, quite good agreement is obtained between the predicted and experimental values, as shown by the listing in Table I. 

For example, the average value of the Si—C bond length found in the methylsilanes (Table 7-6) is 1.87 A. The sum of the single-bond radii of carbon and silicon is 1.94 A, which is 0.07 A larger. If this value is corrected for the 0.7 difference in electronegativity by the Schomaker-Stevenson term it becomes 1.88 A, in much better agreement with experiment. 

Table 11 gives standard covalent radii for most of the elements of the periodic table. Most of these have been calculated from the best data available in the literature using the considerations of paragraphs 1 -3 above. Thus when radii or the appropriate multiplicity and hybridization are added and corrected for difference in electronegativity by the Stevenson and Schomaker relationship, the observed bond length will be obtained. For example, the O-F bond in OF would have the value 0.745 + 0.709 — 0.910.5) = 1.409 A. The experimental value is 1.41 A. 

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