The self-condensation of a derivative of o-aminobenzaldehyde. Structure of the polycyclic bisanhydro trimer of 2-amino-5-bromobenzaldehyde

The structure of the title compound 6,14,22-tri-bromo-19-ethoxy-2,10,18-triazahexacyclo[18.4.0.-0(2,11).0(3,18).0(4,9).0(12,17]tetracosa-1(24),4(9),5,7,12(17),-13,15,20,22-nonaene monohydrate, C23H18Br3N3O.H2O, a bisanhydro trimer hydrate formed from the acid-catalyzed self-condensation of 2-amino-5-bromobenzaldehyde, substantiates the geometry proposed for the similar trimer of o-aminobenzaldehyde (OAB). The tricyclic molecule is an ethoxy derivative rather than a hydroxy derivative as previously observed with OAB. Formation of the ethoxy derivative is a direct result of the condensation reaction having been carried out in ethanol. A water molecule of crystallization appears to be strongly hydrogen bonded to one N atom (O-H...N 2.88 angstrom) and weakly hydrogen bonded to the protonated N atom (N-H...O 3.28 angstrom).