The reaction of 1-adamantyl isothiocyanate 4 with the various cyclic secondary amines yielded the corresponding N-(1-adamantyl)carbothioamides 5a–e, 6, 7, 8a–c and 9.

The title compound, C18H20N4O2S2, is a new 1,3,4-oxa­diazole and a key pharmacophore of several biologically active agents. It is composed of a meth­yl(thio­phen-2-yl)-1,3,4-oxa­diazole-2(3H)-thione moiety linked to a 2-meth­oxy­phenyl unit via a piperazine ring that has a chair conformation. The thio­phene ring mean plane lies almost in the plane of the oxa­diazole ring, with a dihedral angle of 4.35 (9)°. The 2-meth­oxy­phenyl ring is almost normal to the oxa­diazole ring, with a dihedral angle of 84.17 (10)°.

Comprehensive investigation of molecular geometry and electronic structure of 5-(4-Pyridinyl)-1,3,4-thiadiazol-2-amine in ground as well as in the first excited state has been carried out. The stable conformers of the title compound have been determined from the 3D potential energy scan by varying selected dihedral angles, responsible for conformational flexibility. As the energy difference between the conformers was very small, the relative stability has been confirmed at potentially high-level G2MP2 method.