title: Structural characterization of selenium and selenium-diiodine analogues of the antithyroid drug 6-n-propyl-2-thiouracil and its alkyl derivatives.
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, C(5)H(6)N(2)OSe (1), 6-ethyl-2-selenouracil, C(6)H(8)N(2)OSe (2), 6-n-propyl-2-selenouracil, C(7)H(10)N(2)OSe (3), and 6-isopropyl-2-selenouracil, C(7)H(10)N(2)OSe (4), are described, along with that of the dichloromethane monosolvate of 6-isopropyl-2-selenouracil, C(7)H(10)N(2)OSe.CH(2)Cl(2) (4.CH(2)Cl(2)). 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), C(7)H(10)N(2)OSe.I(2) (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-ethyl-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.
authors.affiliation: Section of Inorganic and Analytical Chemistry, Department of Chemistry, University of Ioannina, 45110 Ioannina, Greece.
authors.forename: Constantinos D
authors.initials: CD
authors.lastname: Antoniadis
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: Blake
authors.forename: Sotiris K
authors.initials: SK
authors.lastname: Hadjikakou
authors.forename: Nick
authors.initials: N
authors.lastname: Hadjiliadis
authors.forename: Peter
authors.initials: P
authors.lastname: Hubberstey
authors.forename: Martin
authors.initials: M
authors.lastname: Schröder
authors.forename: Claire
authors.initials: C
authors.lastname: Wilson
mesh_terms: D013956:Antithyroid Agents / Q000737:chemistry*; D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D008958:Models, Molecular; D015394:Molecular Structure; D011441:Propylthiouracil / Q000031:analogs & derivatives* / Q000737:chemistry; D018036:Selenium Compounds / Q000737:chemistry
chemical_list: D013956:Antithyroid Agents; D018036:Selenium Compounds; D011441:Propylthiouracil