The gas-phase acidities of the elemental hydrides are functions of electronegativity and bond length

摘要

The gas-phase Bronsted acidities of the group 1,group 2,and main group elemental hydrides (XH_n) are shown to be a combined function of the bond length,electronegativity,and position in the periodic table,via a separation of the acidity into coulombic and electronic reorganization enthalpy parts.The Coulombic acidity is defined as the enthalpy to separate unit positive and negative charges from the neutral acid's X-H bond length to infinity; the reorganization enthalpy is the difference between that and the measured acidity,and represents the enthalpy required to reorganize the electrons of the neutral acid,creating an ion pair at the original bond distance.Predictions are made for the gas-phase Bronsted acidities of several elemental hydrides for which this quantity is not known.