F. Deproft et al., ACIDITY OF FIRST-ROW AND SECOND-ROW HYDRIDES - EFFECTS OF ELECTRONEGATIVITY AND HARDNESS, International journal of quantum chemistry, 55(6), 1995, pp. 459-468
A study is made on the influence of the electronegativity and hardness
of a group X on the gas-phase acidities of the first- and second-row
hydrides HX. It is shown that these two density functional theory (DFT
)-based global properties are sufficient for the correct description o
f the gas-phase acidity sequences, the group hardness being the more i
mportant factor and describing the influence of polarizability effects
in the charged forms of the acid-base equilibrium. Various calculated
properties of the traditional quantum chemical type (Mulliken charges
and the MEP) and DFT-based (local softness), associated with the neut
ral form of the acid, were found to contain a certain periodicity in t
heir description of the gas-phases acidities. The gas-phase acidities
(Delta H-acid and Delta G(acid) values) were also obtained theoretical
ly via quantum statistical thermodynamical calculations at the Hartree
-Fock level with the 6-31 + G() basis set; these calculated acidities
were in fair agreement with the experimental ones. (C) 1995 John Wile
y & Sons, Inc.