Acta Crystallographica Section C

Crystal Structure Communications

Volume 69, Part 1 (January 2013)

organic compounds

fg3285 scheme

Acta Cryst. (2013). C69, 93-100 [ doi:10.1107/S010827011204930X ]

Five pseudopolymorphs of 6-amino-2-thiouracil: absence of N-HS hydrogen bonds

W. M. Hützler and M. Bolte

Abstract: In order to study the preferred hydrogen-bonding pattern of 6-amino-2-thiouracil, C₄H₅N₃OS, (I), crystallization experiments yielded five different pseudopolymorphs of (I), namely the dimethylformamide disolvate, C₄H₅N₃OS·2C₃H₇NO, (Ia), the dimethylacetamide monosolvate, C₄H₅N₃OS·C₄H₉NO, (Ib), the dimethylacetamide sesquisolvate, C₄H₅N₃OS·1.5C₄H₉NO, (Ic), and two different 1-methylpyrrolidin-2-one sesquisolvates, C₄H₅N₃OS·1.5C₅H₉NO, (Id) and (Ie). All structures contain R₂¹(6) N-HO hydrogen-bond motifs. In the latter four structures, additional R₂²(8) N-HO hydrogen-bond motifs are present stabilizing homodimers of (I). No type of hydrogen bond other than N-HO is observed. According to a search of the Cambridge Structural Database, most 2-thiouracil derivatives form homodimers stabilized by an R₂²(8) hydrogen-bonding pattern, with (i) only N-HO, (ii) only N-HS or (iii) alternating pairs of N-HO and N-HS hydrogen bonds.

Formula: C₄H₅N₃OS·2C₃H₇NO, C₄H₅N₃OS·C₄H₉NO, C₄H₅N₃OS·1.5C₄H₉NO and C₄H₅N₃OS·1.5C₅H₉NO


	Portable Document Format (PDF) file [ doi:10.1107/S010827011204930X/fg3285sup7.pdf ] Supplementary material

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