A Study of the Reduced States of Four Isomeric Bidiazines (Diaza‐2,2′‐ bipyridines) by UV‐VIS/NIR‐Spectroelectrochemistry

Singly and doubly reduced forms of the four isomeric bidiazines 2,2′-bipyrazine, 3,3′-bipyridazine, 2,2′- and 4,4′-bipyrimidine have been generated in a spectroelectrochemical cell and studied by UV–VIS/NIR spectroscopy. As derivatives of 2,2′-bipyridine the compounds exhibit several groups of vibrationally structured long-wavelength bands in the paramagnetic anion radical state. The assignments and variations of transition energies depending on the diaza perturbation may be rationalized using CNDO/S configuration interaction calculations.