Tetra-n-butyl-ammonium orotate monohydrate: knowledge-based comparison of the results of accurate and lower-resolution analyses and a non-routine disorder refinement.
Acta Crystallogr E Crystallogr Commun
; 75(Pt 11): 1632-1637, 2019 Nov 01.
Article
en En
| MEDLINE
| ID: mdl-31709081
ABSTRACT
The title hydrated mol-ecular salt (systematic name tetra-n-butyl-ammonium 2,6-dioxo-1,2,3,6-tetra-hydro-pyrimidine-4-carboxyl-ate monohydrate), C16H36N+·C5H3N2O4 -·H2O, crystallizes with N-Hâ¯O and O-Hâ¯O hydrogen-bonded double-stranded anti-parallel ribbons consisting of the hydro-philic orotate monoanions and water mol-ecules, separated by the bulky hydro-phobic cations. The hydro-phobic and hydro-philic regions of the structure are joined by weaker non-classical C-Hâ¯O hydrogen bonds. An accurate structure analysis conducted at T = 100â
K is compared to a lower-resolution less accurate determination using data measured at T = 295â
K. The results of both analyses are evaluated using a knowledge-based approach, and it is found that the less accurate room-temperature structure analysis provides geometric data that are similar to those derived from the accurate low-temperature analysis, with both sets of results consistent with previously analyzed structures. A minor disorder of one methyl group in the cation at low temperature was found to be slightly more complex at room temperature; while still involving a minor fraction of the structure, the disorder at room temperature was found to require a non-routine treatment, which is described in detail.
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2019
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Article