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Ab initio MO calculations on the acidities of water and methanol, and hydrogen bond energies of the conjugate ions with a water molecule
Author(s) -
Ikuta Shigeru
Publication year - 1984
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.540050415
Subject(s) - chemistry , ab initio , solvation , deprotonation , ion , molecule , hydrogen bond , ab initio quantum chemistry methods , aqueous solution , computational chemistry , organic chemistry
The acidities, deprotonation energies, of water and methanol were calculated by the use of the ab initio self‐consistent‐field ( SCF ) molecular orbital ( MO ) method with electron correlation computed by the thirdorder Møller–Plesset perturbation method and configuration interaction with double excitations. Zero‐point vibrational energy correction translational energy change, and the PV work term were included to evaluate the accurate acidities. The calculated acidity difference including these corrections was 7 kcal/mol, which is somewhat smaller than the experimental ones (9.5–12.5 kcal/mol) recently determined. The hydrogen bond energies of the conjugate ions (OH − and CH 3 O − ) with a water molecule were calculated to be 2.3 kcal/mol near the Hartree–Fock limit; this energy only amounts to 25% of the (total) hydration energy difference between the two negative ions. The aqueous solvation effect on the acidity scale was discussed.