Copper(II)-assisted hydrolysis of cyclic ureas: Transformation of 1-(pyridin-2-yl)-2,3,7,8-tetrahydro-1 H -imidazo[2,1- b ][1,3,5]triazepin-5(6 H )-ones into N 1 -[1-(pyridin-2-yl)imidazolidin-2-ylidene]-ethane-1,2-diamine ligands

•Synthesis of copper(II) complexes of 1-[pyridin-2-yl]-2,3,7,8-tetrahydro-1H-imidazo[2,1-b][1,3,5]triazepin-5(6H)-ones.•Synthesis of copper(II) complexes of N1-[1-(pyridin-2-yl)imidazolidin-2-ylidene]ethane-1,2-diamine.•Copper(II)-assisted hydrolysis of NH-CO bond in cyclic ureas.•X-ray crystallographic structure analysis of copper(II) complexes.•Quantum chemical calculations of ligands and copper(II) complexes.