Zm. Hu et Cg. Zhan, MBOHO CALCULATIONS OF C-H STRETCHING FREQUENCIES IN HYDROCARBONS AND HETEROSUBSTITUTED HYDROCARBONS, International journal of quantum chemistry, 52(1), 1994, pp. 109-116
Based on the generalized relationship for calculating the nuclear spin
-spin coupling constants and the correlation of the bond stretching fr
equencies with the coupling constants, a novel generalized relationshi
p, which includes the contributions of not only the hybrid orbitals, b
ut also the net atomic charges, is introduced for calculation of the b
ond stretching frequencies and employed to elucidate the C-H stretchin
g frequencies in hydrocarbons and heterosubstituted hydrocarbons on th
e basis of the MBOHO calculation employing the CNDO/2 approximation. B
y use of the obtained concrete relationships, one can get different nu
BAR(CH) value for the C-H bonds existing in different chemical environ
ments, which is coincident with chemical intuition. The calculated num
erical results show that for hydrocarbons the contribution of the net
atomic charges can be neglected, but it is necessary for heterosubstit
uted hydrocarbons to include the contribution of the net atomic charge
s to the C-H stretching frequencies. The calculated C-H stretching fre
quencies are in good agreement with the experimental data, which shows
its reasonableness. (C) 1994 John Wiley & Sons, Inc.