A quantum-chemical study of some properties and reactions of H2CN−, H2CN+, H2CNH2+, H2CNH, and HCN, using small and intermediate-sized sets of basis functions

Abstract

It is suggested that given two molecules potentially capable of being involved in the same reaction, one as a product and one as a reactant, it seems reasonable that the calculated difference in energy between these molecules may become relatively constant with smaller basis sets than the calculated energies themselves. To examine this suggestion, and at the same time to provide information on small molecules containing bonds related to the nitrile bond, a number of linear combination of atomic orbitals-molecular orbitals-self consistent field (l.c.a.o.-m.o.-s.c.f.) calculations using small or intermediate sizes of basis sets of Gaussian orbitals were performed on H2CNH, H2CN−, H2CNH2+, H2CN+, and HCN. The change of energy in passing from one molecule to another is shown to converge to a reasonably constant value for smaller basis sets than are required for convergence of individual molecular energies.