Structural characterization of selenium and selenium-diiodine analogues of the antithyroid drug 6-n-propyl-2-thiouracil and its alkyl derivatives
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Antoniadis, C. D.
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Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας
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Antoniadis, C. D.
(EN)
The structures of four selenium analogues of the antithyroid drug 6-n-propyl-2-thiouracil [systematic name: 2,3-dihydro-6n-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 6(3) with a brick-wall architecture. The extended structures of (2) and (4) are analogous, being based on a chain of eight-membered R-8(6)(32) hydrogen-bonded rings. In (3) and (4(.)CH(2)Cl(2)), R-2(2)(8) hydrogen bonding links molecules into chains. 6-n-Propyl-2-selenouracil(.)I(2), (C7H10N2OSeI2)-I-. (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-H O-... hydrogen bonds. Re-crystallization of 6-methyl-2-selenouracil or (7) from acetone gave crystals of the diselenides [N-(6'-ethyl-4'-pyrimidone)(6-ethyl-2-selenouracil) (2)(Se-Se)](.)2H(2)O (9(.)2H(2)O) 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-H (...) O and C-H (...) O 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 R-6(6)(24) hydrogen-bonded ring, with each pair of molecules linked by an R-2(2)(8) motif.
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