1-[(4-Chloro­phen­yl)(phen­yl)meth­yl]piperazine-1,4-diium bis­(trichloro­acetate)–trichloro­acetic acid (1/1)

In the title salt adduct, C₁₇H₂₁ClN₂²⁺·2C₂Cl₃O₂⁻·C₂HCl₃O₂, the Cl atom of the dication is disordered over two positions in a 0.915 (3):0.085 (3) ratio. The Cl atoms in the trichloroacetate anions and trichloroacetic acid molecule are also disordered, with refined site-occupation factors of 0.59 (3):0.41 (3), 0.503 (12):0.417 (12) and 0.653 (12):0.347 (12). The piperazine ring adopts a chair conformation, with puckering parameters Q_T = 0.587 (3) Å, θ = 2.6 (2) and Φ 334 (6)°. In the crystal, neighbouring mol­ecules are linked by N—H...O, O—H...O, N—H...Cl, C—H...O and C—H...Cl hydrogen bonds, forming a three-dimensional network.

Ortho­rhom­bic polymorph of (2E)-2-(2,3-dihydro-1H-inden-1-yl­idene)-2,3-di­hydro-1H-inden-1-one

The title compound, C₁₈H₁₄O, is polymorphic at 123 K. The ortho­rhom­bic form reported herein has two independent mol­ecules in the asymmetric unit, with mol­ecular volume 313.5 ų. The previously reported triclinic (P-1) form [Raston & Scott (2000). Green Chem., 2, 49–52] has mol­ecular volume 309.6 ų at the same temperature. All three mol­ecules deviate significantly and systematically from the putative C_s symmetry (δ_r.m.s. = 0.0265, 0.0256, 0.0497 Å). Comparison of the two molecules in the orthorhombic polymorph shows that 16 of the 19 equivalent pairs of framework atoms have a mirror-image pattern of deviations (above/below plane), suggesting that the two are quasi-enanti­omorphs. The pattern of deviations in the triclinic form is nearly the same (13 of 19 atom pairs) as the ortho­rhom­bic form.