Calculated Proton Affinities Research Articles

MO SCF studies of the protonation of carbon monoxide and the nitrogen molecule using gaussian basis sets

Ab initio MO SCF calculations using gaussian basis functions have been performed to study the protonation of carbon monoxide and the nitrogen molecule. The geometry of the protonated species has been investigated in some detail. The calculated proton affinities are 118 kcal/mole for N 2 and 137 kcal/mole for CO, for the most stable ion HCO +.

Theoretical Study on the Proton Affinity of Small Molecules Using Gaussian Basis Sets in the LCAO–MO–SCF Framework

The proton affinities of certain small molecules have been calculated as an energy difference between the parent molecule and the protonated species. Various size Gaussian basis sets were used to see how the calculated proton affinities approximate the experimental values as the wavefunctions approached the Hartree–Fock limit. The correlation between experimental and calculated proton affinities was excellent with the extensive basis sets.

Charge-Dipole Model of Cation Hydration

A systematic attempt to estimate the quantitative validity of the charge-dipole model of cation hydration is made by giving the model a quantum-theoretical structure. It is shown, in the first order of approximation, that physically reasonable results may be obtained for the proton affinity of H2O and the Gibbs potential and entropy of hydrate water. The calculated proton affinity, for example, is different by about 20% from the average of the observed values. It is concluded that because of the structural simplicity of the charge-dipole model a truly quantitative theory of cation hydration may be developed by perturbation-theoretic techniques and the incisive choice of parameters to define the multipole field of the water molecule.

One-Center Basis Set SCF MO's. II. NH3, NH4+, PH3, PH4+

One-center-expanded SCF MO wavefunctions are reported for the ground states of NH3 and PH3 in their planar and in their calculated equilibrium configurations and of NH4+ and PH4+ in their calculated equilibrium configurations. The calculated molecular energies and the geometrical parameters of the determined equilibrium configurations agree well with the experimental values. Good agreement is also obtained for the electric dipole moment and the proton affinity of NH3 while the calculated value of the height of the potential barrier for inversion appears to be too small. For PH3 a good value for the height of the potential barrier is obtained while the calculated electric dipole moment is too large. The calculated proton affinity of PH3 seems to be reasonable. A critical examination of the wavefunctions gives an account of the quality of the several results obtained.