Crystal and molecular structure of the 1:1 complex of 1-piperidineacetic acid with 2,6-dichloro-4-nitrophenol studied by X-ray diffraction and B3LYP calculation

Crystal structure of the 1:1 complex of 1-piperidineacetic acid (PAA) with 2,6-dichloro-4-nitrophenol (DCNP) has been solved by X-ray diffraction. The crystals are triclinic, space group P1¯ with a=7.609(2), b=9.456(2), c=11.206(2) Å, α=103.77(3)°, β=103.21(3)°, γ=96.48(3)°, Z=2 and R=0.0378. PAA is linked with DCNP through the O−⋯HO hydrogen bond of 2.469(2) Å. Two such complexes form a centrosymmetric dimer, (PAA·DCNP)2, in which the PAA moieties, as zwitterions, are joined by two N+-H⋯O hydrogen bonds of 2.869(2) Å, around the symmetry center. The intermolecular C-H⋯O contacts and the intramolecular N+⋯O electrostatic interactions consolidate the crystal lattice. In the isolated dimer molecule, (PAA·DCNP)2, as predicted by the B3LYP/6-31G(d,p) method, the O-H⋯O hydrogen bonds are longer, while the N+-H⋯O ones are shorter than in the crystal.