The self-condensation of o-aminobenzaldehyde: the polycyclic structure of the picrate salt of the diprotonated tetra-anhydro tetramer, 4b,5,15b,16-tetrahydrodibenzo[3,4:7,8][1,5]diazocino-[2,1-b:6,5-b]diquinazoline-11,22-di-ium picrate: X-ray crystal structure

Abstract

An X-ray crystal structure determination shows that the diprotonated tetra-anhydro-tetramer of o-aminobenzaldenyde in the picrate salt, [C₂₈H₂₂N₄][C₆H₂N₃O₇]₂, has a heptacyclic structure (3), rather than that of the macrocyclic isomer (4), and appears to be stabilised by a strong N–H ⋯ O hydrogen bond and a short C-H ⋯ O interaction (C ⋯ O,3·12Å) to the picrate anions.