Excited states and photochemistry of saturated molecules. Part 3.—Structure and bonding in n-alkane excited states using INDO–CI

Abstract

The molecular structures and bond energies in the low-lying excited states of n-alkanes from methane to n-pentane are investigated using the semi-empirical INDO method with configuration interaction. In general the calculated geometries and bond energies are consistent with the known threshold photochemistry of these molecules, the only exception being the prediction of vicinal (rather than geminal) elimination of H₂ in ethane. It appears that INDO overestimates the amount of angular distortion in these excited states.