Toggle Main Menu Toggle Search

Open Access padlockePrints

Stoichiometry-dependent structures: An X-ray and neutron single-crystal diffraction study of the effect of reaction stoichiometry on the crystalline products formed in the potassium-cyanurate system

Lookup NU author(s): Gary Nichol, Emeritus Professor Bill CleggORCiD, Duncan Tooke

Downloads

Full text for this publication is not currently held within this repository. Alternative links are provided below where available.


Abstract

Reaction of cyanuric acid (C3H3N3O 3; neutral form CYH3; anionic form CYH2-; dianionic form CYH2-) with K 2CO3 or KOH in aqueous solution gave three different crystalline products, according to the reaction stoichiometry used. The structures of two products were easily determined by single-crystal X-ray diffraction: [K(CYH2)(H2O)], (1), of which the crystal structure is already known [Marsh, R. E. et al. (2002). Acta Cryst. B58, 62-77], and [K2(CYH)], (2), a highly symmetrical and dense structure. Further stoichiometric variation produced another new complex, (3), and reaction of Rb2CO3 with CYH3 yielded a further product, (4), which was found to be isostructural with (3). Determination of the structures of (3) and (4) by X-ray diffraction gave a result that was chemically unreasonable owing to a charge imbalance, with the asymmetric unit apparently containing 2- against 1.5+ (partial charges as the result of crystallographic mirror symmetry). A single-crystal neutron diffraction analysis carried out on a fully deuterated sample of (3) revealed the presence of a supercell, with the c axis doubled compared with the X-ray result. Subsequent refinement of the structure with this supercell showed that it is the result of just two D atoms breaking crystallographically imposed mirror symmetry, which is otherwise essentially observed by the rest of the structure. This minor deviation from pseudo-symmetry could not be identified by X-ray diffraction. Thus, single-crystal neutron diffraction data revealed that the true chemical formula of the structure of (3) [and presumably also of the isostructural (4) with Rb instead of K and H instead of D], is [K 3(C3D2N3O3) 3(C3D3N3O3)(D 2O)4], the deuterated form of [K3(CYH 2)3(CYH3)(H2O)4]. © 2006 International Union of Crystallography Printed in Great Britain - all rights reserved.


Publication metadata

Author(s): Nichol GS, Clegg W, Gutmann MJ, Tooke DM

Publication type: Article

Publication status: Published

Journal: Acta Crystallographica Section B: Structural Science

Year: 2006

Volume: 62

Issue: 5

Pages: 798-807

ISSN (print): 0108-7681

ISSN (electronic): 1600-5740

Publisher: Wiley-Blackwell

URL: http://dx.doi.org/10.1107/S0108768106025171

DOI: 10.1107/S0108768106025171


Altmetrics

Altmetrics provided by Altmetric


Share