Co-crystallization of 3,5-di-nitro-benzoic acid with two anti-psychotic 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-cyclo-hexyl-1-phenyl-3-(piperidin-1-yl)propan-1-ol (trihexyphenid-yl) with 3,5-di-nitro-benzoic acid gives a simple 1:1 salt, namely 1-(3-cyclo-hexyl-3-hy-droxy-3-phenyl-prop-yl)piperidin-1-ium 3,5-di-nitro-benzoate, C20H32NO+·C7H3N2O6 -, (I), whereas a similar co-crystallization using (Z)-3-(2-chloro-9H-thioxanthen-9-yl)-N,N-di-methyl-propan-1-amine (chlorprothixene) gives a 1:2 acid salt, namely (Z)-3-(2-chloro-9H-thioxanthen-9-yl)-N,N-di-methyl-propan-1-aminium hydrogen bis-(3,5-di-nitro-benzoate), 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 cyclo-hexyl 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 inter-actions 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.