Acta Crystallographica Section B

Structural Science

Volume 62, Part 4 (August 2006)

research papers

Acta Cryst. (2006). B62, 580-591 [ doi:10.1107/S0108768106011426 ]

Structural characterization of selenium and selenium-diiodine analogues of the antithyroid drug 6-n-propyl-2-thiouracil and its alkyl derivatives

C. D. Antoniadis, A. J. Blake, S. K. Hadjikakou, N. Hadjiliadis, P. Hubberstey, M. Schröder and C. Wilson

Abstract: The structures of four selenium analogues of the antithyroid drug 6-n-propyl-2-thiouracil [systematic name: 2,3-dihydro-6-n-propyl-2-thioxopyrimidin-4(1H)-one], namely 6-methyl-2-selenouracil, C₅H₆N₂OSe (1), 6-ethyl-2-selenouracil, C₆H₈N₂OSe (2), 6-n-propyl-2-selenouracil, C₇H₁₀N₂OSe (3), and 6-isopropyl-2-selenouracil, C₇H₁₀N₂OSe (4), are described, along with that of the dichloromethane monosolvate of 6-isopropyl-2-selenouracil, C₇H₁₀N₂OSe·CH₂Cl₂ (4·CH₂Cl₂). The extended structure of (1) is a two-dimensional sheet of topology 6³ with a brick-wall architecture. The extended structures of (2) and (4) are analogous, being based on a chain of eight-membered R₈⁶(32) hydrogen-bonded rings. In (3) and (4·CH₂Cl₂), R₂²(8) hydrogen bonding links molecules into chains. 6-n-Propyl-2-selenouracil·I₂, C₇H₁₀N₂OSe·I₂ (7), is a charge-transfer complex with a `spoke' structure, the extended structure of which is based on a linear chain formed principally by intermolecular N-HO hydrogen bonds. Re-crystallization of 6-ethyl-2-selenouracil or (7) from acetone gave crystals of the diselenides [N-(6'-ethyl-4'-pyrimidone)(6-ethyl-2-selenouracil)₂(Se-Se)]·2H₂O (9·2H₂O) or [N-(6'-n-propyl-4'-pyrimidone)(6-n-propyl-2-selenouracil)₂(Se-Se)] (10), respectively: these have similar extended chain structures formed via N-HO and C-HO hydrogen bonds, stacked to give two-dimensional sheets. Re-crystallization of (7) from methanol/acetonitrile led via deselenation to the formation of crystals of 6-n-propyl-2-uracil (11), in which six symmetry-related molecules combine to form a six-membered R₆⁶(24) hydrogen-bonded ring, with each pair of molecules linked by an R₂²(8) motif.

Keywords: selenouracil; hydrogen bonding; charge-transfer complex; antithyroid drug.


	Structure factor file (CIF format) (87.2 kbytes) [ doi:10.1107/S0108768106011426/so50031sup2.hkl ] Contains datablock 1

	Structure factor file (CIF format) (197.3 kbytes) [ doi:10.1107/S0108768106011426/so50032sup3.hkl ] Contains datablock 2

	Structure factor file (CIF format) (170.4 kbytes) [ doi:10.1107/S0108768106011426/so50033sup4.hkl ] Contains datablock 3

	Structure factor file (CIF format) (282.9 kbytes) [ doi:10.1107/S0108768106011426/so50034sup5.hkl ] Contains datablock 4

	Structure factor file (CIF format) (303.1 kbytes) [ doi:10.1107/S0108768106011426/so50034.CH2Cl2sup6.hkl ] Contains datablock i2mseu

	Structure factor file (CIF format) (130.5 kbytes) [ doi:10.1107/S0108768106011426/so50037sup7.hkl ] Contains datablock 7

	Structure factor file (CIF format) (649.2 kbytes) [ doi:10.1107/S0108768106011426/so50039sup8.hkl ] Contains datablock 9

	Structure factor file (CIF format) (205.7 kbytes) [ doi:10.1107/S0108768106011426/so500310sup9.hkl ] Contains datablock sepmoi

	Structure factor file (CIF format) (86.6 kbytes) [ doi:10.1107/S0108768106011426/so500311sup10.hkl ] Contains datablock i2prse

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