Benzophenone is photoreduced by pthalimidines and dihydro isoquinolones. The hydrogen atom α to the nitrogen atom is abstracted and radical coupling leads to adducts. CIDNP studies of these adducts show inversion of polarisation for the adduct on the N-alkyl chain when the nitrogen is bound to a benzylic methylene. This inversion is explained by considering that the radical on the N-alkyl chain derives