2-Isobutyl-6-phenyl-imidazo[2,1-b][1,3,4]thia-diazole.

In the title compound, C(14)H(15)N(3)S, the imidazo[2,1-b][1,3,4]thia-diazole fused-ring system is close to planar, with a maximum deviation of 0.042 (1) Å, and the dihedral angle between it and the phenyl ring is 24.21 (6)°. The isobutyl group is disordered over two sets of sites in a 0.899 (9):0.101 (9) ratio. In the crystal, weak aromatic π-π stacking inter-actions involving the imidazole and thia-diazole rings with a centroid-centroid distance of 3.8067 (7) Šoccur.

2-Isobutyl-6-(4-meth-oxy-phen-yl)imidazo[2,1-b][1,3,4]thia-diazole.

In the title compound, C(15)H(17)N(3)OS, the dihedral angle between the statistically planar imidazo[2,1-b][1,3,4]thia-dia-zole fused-ring system (r.m.s. deviation = 0.002 Å) and the methyoxbenzene ring is 4.52 (6)°. In the crystal, mol-ecules are arranged into columns and stacked down the a axis. The crystal structure is stabilized by weak C-H⋯π and π-π inter-actions [centroid-centroid separations = 3.6053 (8) and 3.7088 (7) Å].

6-(4-Chloro-phen-yl)-2-isobutyl-imidazo[2,1-b][1,3,4]thia-diazole.

In the title compound, C(14)H(14)ClN(3)S, the imidazo[2,1-b][1,3,4]thia-diazole system is essentially planar, with a maximum deviation of 0.006 (2) Å. The dihedral angle between the imidazo[2,1-b][1,3,4]thia-diazole and chloro-phenyl rings is 5.07 (8)°. In the crystal, there are no classical hydrogen bonds but stabilization is provided by weak π-π [centroid-centroid distance = 3.5697 (11) Å] and C-H⋯π inter-actions.