2,3-Dimethoxy-10-oxostrychnidinium 2-(2,4,6-trinitroanilino)benzoate monohydrate: a 1:1 proton-transfer salt of brucine witho-picraminobenzoic acid

Abstract

In the structure of the title 1:1 proton-transfer compound of brucine with 2-(2,4,6-trinitroanilino)benzoic acid, C(23)H(27)N(2)O(4)(+)·C(13)H(7)N(4)O(8)(-)·H(2)O, the brucinium cations form classic undulating ribbon substructures through overlapping head-to-tail interactions, while the anions and the three related partial solvent water molecules (having occupancies of 0.73, 0.17 and 0.10) occupy the interstitial regions of the structure. The cations are linked to the anions directly through N-H...O(COO(-)) hydrogen bonds and indirectly by the three water molecules, which form similar conjoint cyclic bridging units [graph set R(2)(4)(8)] through O-H...O(C=O) and O-H...O(COO(-)) hydrogen bonds, giving a two-dimensional layered structure. Within the anion, intramolecular N-H...O(COO(-)) and N-H...O(nitro) hydrogen bonds result in the benzoate and picrate rings being rotated slightly out of coplanarity [inter-ring dihedral angle = 32.50 (14)°]. This work provides another example of the molecular selectivity of brucine in forming stable crystal structures, and also represents the first reported structure of any form of the guest compound 2-(2,4,6-trinitroanilino)benzoic acid.