Transition metal-induced reductive coupling of 2-amino-1,3,4-thiadiazole with acetonitrile: Synthesis and structural characterization of two Co(III) complexes with amidine

A planar square Co(III) complex, [Co(HL)(H2L)](ClO4)2 (1) (H2L = N-(1,3,4-thiadiazol-2-yl)acetimidamide, C4H6N4S), was synthesized by mixing Co(II) salt with 2-amino-1,3,4-thiadiazole in acetonitrile, and the subsequent addition of pyridine led to an octahedral Co(III) complex, [Co(HL)2(Py)2](ClO4) · CH3CN (2) (Py = pyridine). To mix 2-amino-1,3,4-thiadiazole, pyridine and cobalt perchlorate directly into acetonitrile can also afford complex 2 in higher yield. Complexes 1 and 2 have been characterized by X-ray single crystal diffraction and cyclic voltammetry, and the reaction mechanism has been discussed.