title: Different patterns of supramolecular assembly in constitutionally similar 6-arylimidazo[2,1-b][1,3,4]thiadiazoles.
abstract: Four imidazo[2,1-b][1,3,4]thiadiazoles containing a simply-substituted 6-aryl group have been synthesized by reaction of 2-amino-1,3,4-thiadiazoles with bromoacetylarenes using microwave irradiation and brief reaction times. 6-(2-Chlorophenyl)imidazo[2,1-b][1,3,4]thiadiazole, C(10)H(6)ClN(3)S, (I), 6-(2-chlorophenyl)-2-methylimidazo[2,1-b][1,3,4]thiadiazole, C(11)H(8)ClN(3)S, (II), 6-(3,4-dichlorophenyl)imidazo[2,1-b][1,3,4]thiadiazole, C(10)H(5)Cl(2)N(3)S, (III), and 6-(4-fluoro-3-methoxyphenyl)-2-methylimidazo[2,1-b][1,3,4]thiadiazole, C(12)H(10)FN(3)OS, (IV), crystallize with Z' values of 2, 1, 1 and 2 respectively. The molecular skeletons are all nearly planar and the dihedral angles between the imidazole and aryl rings are 1.51 (8) and 7.28 (8)° in (I), 9.65 (7)° in (II), 10.44 (8)° in (III), and 1.05 (8) and 7.21 (8)° in (IV). The molecules in (I) are linked by three independent C-H...N hydrogen bonds to form ribbons containing alternating R2(2)(8) and R4(4)(18) rings, and these ribbons are linked into a three-dimensional array by three independent π-stacking interactions. Both (II) and (III) contain centrosymmetric dimers formed by π-stacking interactions but hydrogen bonds are absent, and the molecules of (IV) are linked into centrosymmetric R2(2)(8) dimers by C-H...N hydrogen bonds. Comparisons are made with a number of related compounds.
authors.affiliation: Department of Studies in Chemistry, University of Mysore, Manasagangotri, Mysore 570 006, India.
authors.forename: Aletti S
authors.initials: AS
authors.lastname: Praveen
authors.affiliation: Department of Studies in Chemistry, University of Mysore, Manasagangotri, Mysore 570 006, India.
authors.forename: Hemmige S
authors.initials: HS
authors.lastname: Yathirajan
authors.affiliation: Department of Studies in Chemistry, University of Mysore, Manasagangotri, Mysore 570 006, India.
authors.forename: Manpreet
authors.initials: M
authors.lastname: Kaur
authors.affiliation: Department of Studies in Chemistry, Mangalore University, Mangalagangotri 574 199, India.
authors.forename: Badiadka
authors.initials: B
authors.lastname: Narayana
authors.affiliation: Department of Chemistry, Nelson Mandela Metropolitan University, Summerstrand Campus (South), University Way, Summerstrand, PO Box 77000, Port Elizabeth, 6031, South Africa.
authors.forename: Eric C
authors.initials: EC
authors.lastname: Hosten
authors.affiliation: Department of Chemistry, Nelson Mandela Metropolitan University, Summerstrand Campus (South), University Way, Summerstrand, PO Box 77000, Port Elizabeth, 6031, South Africa.
authors.forename: Richard
authors.initials: R
authors.lastname: Betz
authors.affiliation: School of Chemistry, University of St Andrews, Fife KY16 9ST, Scotland.
authors.forename: Christopher
authors.initials: C
authors.lastname: Glidewell
mesh_terms: D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D007093:Imidazoles / Q000737:chemistry*; D015394:Molecular Structure; D013830:Thiadiazoles / Q000737:chemistry*
chemical_list: C000593304:6-(2-chlorophenyl)-2-methylimidazo(2,1-b)(1,3,4)thiadiazole; C000593303:6-(2-chlorophenyl)imidazo(2,1-b)(1,3,4)thiadiazole; C000593305:6-(3,4-dichlorophenyl)imidazo(2,1-b)(1,3,4)thiadiazole; D007093:Imidazoles; D013830:Thiadiazoles; C029899:imidazole
keywords: crystal structure; hydrogen bonding; imidazo[2,1-b][1,3,4]thiadiazoles; molecular conformation; pharmaceutical compounds; supramolecular assembly