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Cocrystals of barbituric acid with alkali metal halides

Lookup NU author(s): Emeritus Professor Bill Clegg, Gary Nichol

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Abstract

Barbituric acid BAH reacts with potassium, rubidium and caesium iodides in methanol, forming anhydrous BAH·MI. BAH·CsI has a different 8-fold coordination geometry from corresponding alkali metal bromides, intermediate between triangular dodecahedral and square antiprismatic. BAH·KI and BAH·RbI display features that are new for this family, with a high coordination number of 9, and with no involvement of iodide in either coordination or hydrogen bonding, its environment being six BAH molecules. BAH·NaCl·2H2O, prepared by successive treatment of BAH in water with sodium hydroxide and dilute hydrochloric acid, is isostructural with other chlorides and bromides, with 7-coordinate Na+ and a network of hydrogen bonding. Two BAH molecules are oxidatively coupled by aqueous potassium permanganate to generate 5-hydroxyhydurilic acid, isolated as a hydrated potassium salt with K+ in an unusually low 5-coordination. The folding of the BAH molecule in its full range of known crystal structures is analysed; the dihedral folding angle ranges from 0 to approximately 20 °, uncorrelated with any other particular features of the structures.


Publication metadata

Author(s): Clegg W, Nichol GS, Patel A

Publication type: Article

Publication status: Published

Journal: Croatica Chemica Acta

Year: 2018

Volume: 91

Issue: 2

Pages: 241-248

Online publication date: 29/06/2018

Acceptance date: 06/06/2018

ISSN (print): 0011-1643

ISSN (electronic): 1334-417X

Publisher: Croatian Chemical Society

URL: https://doi.org/10.5562/cca3361

DOI: 10.5562/cca3361


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