Theory of Formamide and Its Related Compounds by INDO–CI Method

Abstract

To calculate the optical absorption of formamide and its related compounds, the INDO method for valence-shell electrons is extended to include the change in valence-state electron configurations. All the molecular integrals are parametrized as functions of electron densities. The singlet states of those amides are then determined with a due account of CI, including all the singly-excited and the simultaneous doubly-excited configurations. It is thus shown for formamide that the lowest four transitions can be assigned as n-π^*, NV₁, n′-π^* and NV₂, and that the calculated absorption agrees with the observation. It is also shown from the calculation on related compounds that the methyl substitution of hydrogen atom(s) exerts a considerable influence on NV₁- and NV₂-transition, and that the calculated directions of NV₁-transition moment are in a satisfactory agreement with the observed ones.