Synthesis and crystal structure analysis of 2-(4-fluorobenzyl)-6-phenylimidazo[2,1-b][1,3,4]thiadiazole and its chlorophenyl derivative

Crystal structures of three 6-aryl-2-(4-chloro-benz-yl)-5-[(1H-indol-3-yl)meth-yl]imidazo[2,1-b][1,3,4]thia-diazo-les

Three title compounds, namely, 2-(4-chloro-benz-yl)-5-[(1H-indol-3-yl)meth-yl]-6-phenyl-imidazo[2,1-b][1,3,4]thia-diazole, C26H19ClN4S, (I), 2-(4-chloro-benz-yl)-6-(4-fluoro-phen-yl)-5-[(1H-indol-3-yl)meth-yl]imidazo[2,1-b][1,3,4]thia-diazole, C26H18ClFN4S, (II), and 6-(4-bromo-phen-yl)-2-(4-chloro-benz-yl)-5-[(1H-indol-3-yl)meth-yl]imidazo[2,1-b][1,3,4]thia-diazole, C26H18BrClN4S, (III), have been prepared using a reductive condensation of indole with the corresponding 6-aryl-2-(4-chloro-benz-yl)imidazo[2,1-b][1,3,4]thia-diazole-5-carbaldehydes (aryl = phenyl, 4-fluoro-phenyl or 4-bromo-phen-yl), and their crystal structures have been determined. The asymmetric unit of compound (I) consists of two independent mol-ecules and one of the mol-ecules exhibits disorder of the 4-chloro-benzyl substituent with occupancies 0.6289 (17) and 0.3711 (17). Each type of mol-ecule forms a C(8) chain motif built from N-H⋯N hydrogen bonds, which for the fully ordered mol-ecule is reinforced by C-H⋯π inter-actions. In compound (II), the chloro-benzyl unit is again disordered, with occupancies 0.822 (6) and 0.178 (6), and the mol-ecules form C(8) chains similar to those in (I), reinforced by C-H⋯π inter-actions involving only the major disorder component. The chloro-benzyl unit in compound (III) is also disordered with occupancies of 0.839 (5) and 0.161 (5). The mol-ecules are linked by a combination of one N-H⋯N hydrogen bond and four C-H⋯π inter-actions, forming a three-dimensional framework.