PROTON CONTACT SHIFT STUDY OF BENZAZOLES: INTER-RING SPIN DELOCALIZATION
Large downfield shifts induced by bis(acetylacetonato)nickel(II) have been observed for the H-7 resonances in various benzazoles (II–X); these proton contact-shifts are explained in terms of the inter-ring spin delocalization through σ-skeletons in a zig-zag arrangement.