This article presents the synthesis method and structural study of a new 1,10-phenanthroline-tris(2-amino-5-ethylthio-1,3,4-
thiadiazole)copper(II)perchlorate complex formed with copper perchlorate and the ligands 2-amino-5-ethylthio-1,3,4-thiadiazole and 1,10-phenanthroline. The structure of the obtained complex was investigated using modern quantumchemical calculations, Frontier Molecular Orbital (FMO) analysis, infrared spectroscopy, scanning electron microscopy (SEM) and differential thermal analysis and X-ray Structural Analysis (RSA). The [CuL3(phen)](ClO4)2 complex exhibits a tetragonal pyramidal structure with a five-coordinate geometry, where the Cu(II) ion coordinates to three nitrogen atoms of the thiadiazol rings and two nitrogen atoms of the bidentate phenanthroline ligand, while two perchlorate anions are located in the outer sphere of the complex.