Yr. Luo et Jl. Holmes, THE PREDICTION OF BOND-DISSOCIATION ENERGIES FOR COMMON ORGANIC-COMPOUNDS, Journal of molecular structure. Theochem, 100(2-3), 1993, pp. 123-129
An empirical equation has been developed which reproduces bond dissoci
ation energy (BDE) values for 65 common organic compounds with an aver
age deviation of less than 0.6 kcal mol-1. The equation is DH-degrees(
R-X)est = DH-degrees(CH3-X)obs - m(6.33 + 0.36 m -V(x)/0.67 + 0.21 m)
+ DELTAV(nb) where DH-degrees(R-X)est is the bond strength to be estim
ated (for R = ethyl, sec-propyl or t-butyl); X is one of a wide variet
y of substituents; DH-degrees(CH3-X)obs is the key experimentally meas
ured (CH3-X) bond strength; m is the number of methyl groups substitut
ed in CH3; V(x) is the covalent potential; DELTAV(nb) is the relief of
steric strain between non-bonded atoms when the free radical pair is
separated. The equation thus takes into account both inductive effects
, related to a new scale of electronegativity, and structural effects.