Z. Dega‐Szafran, G. Dutkiewicz, Z. Kosturkiewicz
Mar 2, 2004
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0
Influential Citations
6
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Journal
Journal of Molecular Structure
Abstract
Abstract The 1:1 complex of 1-piperidineacetic acid (PAA) with HCl has been studied by X-ray diffraction and by B3LYP/6-31G(d,p) and PM3 calculations. The crystals are monoclinic, space group P 2 1 / c , a =13.268(1), b =6.349(1), c =11.083(1) A, β =99.79(1)°, Z =4, R =0.0372. The carboxylate group of PAA is protonated and forms the O–H⋯Cl − hydrogen bond with chlorine anion (2.964(1) A). The chlorine anion is also engaged in the N + –H⋯Cl − hydrogen bond (3.062(1) A) and C–H⋯Cl − contacts (3.552(2) and 3.784(2) A), consolidating the layers forming their hydrophilic internal areas. On both sides of the layers there are hydrophobic piperidinium residues having only van der Waals contacts with the next sandwich-like layers. In the optimised by the B3LYP/6-31G(d,p) calculations two protonated molecules of PAA are joined by the O–H⋯Cl − and N + –H⋯Cl − hydrogen bonds forming the cyclic dimer. In the structure predicted by the PM3 method the neutral PAA molecule is engaged in the N⋯H–Cl hydrogen bond, two such molecules are connected by one O–H⋯Cl hydrogen bond forming an open dimer. The molecular structures of complexes of simple amino acids with mineral acids are discussed.