Mononuclear mixed-ligand complexes with 4-phenyl-5-pyridin-4-yl-2,4-dihydro-1,2,4-triazole-3-thione and ethylenediamine: Syntheses, spectral and X-ray crystallographic characterization

Two mononuclear mixed-ligand complexes [Ni(en)2(ppdtt)2]·2H2O (1) and [Cu(en)2(ppdtt)2]·2H2O (2) have been synthesized with Hppdtt = 4-phenyl-5-pyridin-4-yl-2,4-dihydro-1,2,4-triazole-3-thione and ethylenediamine (en). The compounds have been characterized by elemental analyses, IR, UV–Vis, ESR, magnetic susceptibility, cyclic voltammetry and single crystal X-ray studies. The geometry of complexes 1 and 2 are distorted octahedral. The complexes 1 and 2 crystallized in the orthorhombic and monoclinic systems with space groups P b c a and P 21/n, respectively. Both complexes 1 and 2 show quasi-reversible redox behaviour assignable to M2+/M3+ one electron transfer. An ESR signal was registered for complex 2. Hydrogen bonds together with π–π and C–H⋯π interactions play an important role in the formation of the final supramolecular framework.