Electronic structure and low-energy photoelectron spectra of 4,4′-disubstituted 2,2′-bipyridines

Abstract

The He I photoelectron spectra of 4,4′-(di-X)-2,2′-bipyridines [X = H, Cl, CH₃, N(CH₃)₂] are reported. The low-energy regions of the spectra arising from orbitals which correlate with the a₂(π), a₁(n_N) and b₁(π) orbitals of pyridine are assigned using the results of ab initio calculations on pyridine and 2,2′-bipyridine, together with spectra of the 4-substituted pyridines.