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 P 1 with aZ7.609(2), bZ9.456(2), cZ11.206(2) A ° , aZ103.77(3)8, bZ103.21(3)8, gZ 96.48(3)8, ZZ2 and RZ0.0378. PAA is linked with DCNP through the OK/HO hydrogen bond of 2.469(2) A ° . Two such complexes form a centrosymmetric dimer, (PAA$DCNP)2, in which the PAA moieties, as zwitterions, are joined by two NC–H/O hydrogen bonds of 2.869(2) A ° , around the symmetry center. The intermolecular C–H/O contacts and the intramolecular NC/O electrostatic interactions consolidate the crystal lattice. In the isolated dimer molecule, (PAA$DCNP)2, as predicted by the B3LYP/6-31G(d,p) method, the O–H/O hydrogen bonds are longer, while the NC–H/O ones are shorter than in the crystal. q 2005 Elsevier B.V. All rights reserved.