Abstract: In the title compound, 2C(3)H(8)NO(2)S(+)center dot C2O42-, the oxalate anion occupies an inversion centre and is coordinated to cysteine molecules of different chirality (L and D) via O-H center dot center dot center dot O and N-H center dot center dot center dot O hydrogen bonds, the resulting cysteine-oxalate stoichiometry in the crystal structure being 2:1. The oxalate anion is completely deprotonated, whereas cysteine has a positively charged -NH3+ group and a neutral protonated carboxyl group. The structure is built from infinite hydrogen-bonded triple layers, consisting of an oxalate layer in the middle with layers of L- and D-cysteine molecules on either side. The thiol groups are at the external sides of the layers and form S-H center dot center dot center dot O hydrogen bonds with the carboxyl groups of neighbouring cysteine molecules. An interesting feature of the structure is the occurrence of short S center dot center dot center dot S contacts between SH groups of molecules in neighbouring layers, which form not S-H center dot center dot center dot S but S-H center dot center dot center dot O intermolecular hydrogen bonds. Due to the effects of crystal packing and intermolecular hydrogen-bond formation, the conformation of the cysteine cation in the title structure is different from that calculated theoretically for an individual cation, as well as from those of cysteine zwitterions in crystals of pure cysteine.

Cite: Drebushchak T.N. , Bizyaev S.N. , Boldyreva E.V.
Bis(DL-cysteinium) oxalate
Acta Crystallographica Section C: Structural Chemistry. 2008. V.64. P.O313-O315. DOI: 10.1107/S0108270108012341 WOS Scopus РИНЦ

Dates:

Published online:	May 14, 2008
Published print:	Jun 15, 2008

Identifiers:

Web of science	WOS:000256468200011
Scopus	2-s2.0-44949174909
Elibrary	13573675
OpenAlex	W1971023105

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