Diastereomeric complex of (R/S)-piperidine-3-carboxylic acid with (2R,3R)-tartaric acid: Structural, spectroscopic and computational studies
2011
Bartoszak-Adamska, E. | Dega-Szafran, Z. | Jaskólski, M. | Szafran, M.
2:2 Complex of (R) and (S)-piperidine-3-carboxylic acids (P3C) with (2R,3R)-tartaric acid (TA), 1, has been characterized by single-crystal X-ray analysis, FTIR and NMR spectroscopies, and by DFT calculations. The crystals of 1 are monoclinic, space group P2₁. The crystal structure is formed by two distinct P3CH⁺·TA⁻ components, A and B, linked by an O–H⋯O hydrogen bond of 2.603(2)Å. The A and B components differ in the absolute configuration of the C(3) atom of P3CH⁺; (S) in A and (R) in B. The piperidinium-3-carboxylic acid and (2R,3R)-semi-tartrate anion moieties of the components A and B are linked by O–H⋯O hydrogen bonds of 2.517(1) and 2.535(1)Å, respectively. In A and B the piperidinium rings adopt the chair conformation with the carboxyl group in the equatorial position. The structures of the monomers of P3CH⁺·TA⁻, 3A and 3B, as well as of a dimer 2, have been optimized by the B3LYP/6-31G(d,p) approach. The chemical shift assignments were based on two-dimensional ¹H–¹H and ¹H–¹³C experiments.
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