Co-crystallization of 3,5-dinitrobenzoic acid with two antipsychotic agents: a simple 1:1 salt with trihexyphenidyl and a 1:2 acid salt containing a very short O—H...O hydrogen bond with chlorprothixene

Co-crystallization of racemic 1-cyclohexyl-1-phenyl-3-(piperidin-1-yl)propan-1-ol (trihexyphenidyl) with 3,5-dinitrobenzoic acid gives a simple 1:1 salt, namely 1-(3-cyclohexyl-3-hydroxy-3-phenylpropyl)piperidin-1-ium 3,5-dinitrobenzoate, C20H32NO+·C7H3N2O6−, (I), whereas a similar co-crystallization using (Z)-3-(2-chloro-9H-thioxanthen-9-yl)-N,N-dimethylpropan-1-amine (chlorprothixene) gives a 1:2 acid salt, namely (Z)-3-(2-chloro-9H-thioxanthen-9-yl)-N,N-dimethylpropan-1-aminium hydrogen bis(3,5-dinitrobenzoate), C18H19ClNS+·[H(C7H3N2O6)2]−, (II), the anion of which contains a very short O—H...O hydrogen bond, with dimensions O—H = 1.04 (3) Å, H...O = 1.41 (3) Å, O...O = 2.4197 (15) Å and O—H...O = 161 (3)°. In the cation of (I), the cyclohexyl and piperidyl rings both adopt chair conformations, whereas in the cation of (II), the central heterocyclic ring adopts a boat conformation, so that the dihedral angle between the two aryl rings is 41.56 (4)°. A combination of O—H...O, N—H...O and C—H...O hydrogen bonds links the ions of (I) into a complex chain of rings, and these chains are linked into sheets by π–π stacking interactions between inversion-related pairs of anions. In compound (II), a different combination of O—H...O, N—H...O and C—H...O hydrogen bonds links the ions into sheets. Comparisons are made with some related structures.