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MBOHO calculations of CH stretching frequencies in hydrocarbons and heterosubstituted hydrocarbons
Author(s) -
Hu ZhenMin,
Zhan ChangGuo
Publication year - 1994
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560520111
Subject(s) - cndo/2 , chemistry , atomic orbital , coupling constant , force constant , computational chemistry , molecular orbital , atomic physics , thermodynamics , molecular physics , molecule , quantum mechanics , physics , organic chemistry , electron
Based on the generalized relationship for calculating the nuclear spin–spin coupling constants and the correlation of the bond stretching frequencies with the coupling constants, a novel generalized reationship, which includes the contributions of not only the hybrid orbitals, but also the net atomic charges, is introduced for calculation of the bond stretching frequencies and employed to elucidate the CH stretching frequencies in hydrocarbons and heterosubstituted hydrocarbons on the basis of the MBOHO calculation employing the CNDO /2 approximation. By use of the obtained concrete realtionships, one can get different ν CH value for the CH bonds existing in different chemical environments, which is coincident with chemical intuition. The calculated numerical results show that for hydrocarbons the contribution of the net atomic charges can be neglected, but it is necessary for heterosubstituted hydrocarbons to include the contribution of the net atomic charges to the CH stretching frequencies. The calculated CH stretching frequencies are in good ageement with the experimental data, which shows its reasonableness. © 1994 John Wiley & Sons, Inc.