Copper(II)-assisted hydrolysis of cyclic ureas: Transformation of 1-(pyridin-2-yl)-2,3,7,8-tetrahydro-1H-imidazo[2,1-b][1,3,5]triazepin-5(6H)-ones into N1-[1-(pyridin-2-yl)imidazolidin-2-ylidene]-ethane-1,2-diamine ligands

• Published in: Inorganica Chimica Acta 2017-10, Vol.467, p.287-296
• Main Authors: Balewski, Łukasz, Gdaniec, Maria, Sączewski, Jarosław, Wicher, Barbara, Sączewski, Franciszek
• Format: Article
• Language: English
• ISSN: 0020-1693; 1873-3255
• DOI: 10.1016/j.ica.2017.08.032

[Display omitted] •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. The reaction of bidentate 1-(pyridin-2-yl)-2,3,7,8-tetrahydro-1H-imidazo[2,1-b][1,3,5]triazepin-5(6H)-one ligands (3a–g) with copper(II) chloride, carried out at ambient temperature in aqueous EtOH or DMF, led to the formation of corresponding complexes 4 of type [Cu(L)(Cl)2], which in the presence of water and excess of Cu2+ ions provided copper(II) complexes (5) of tridentate N1-[1-(pyridin-2-yl)imidazolidin-2-ylidene]ethane-1,2-diamine ligands of the formula {[Cu(L)(μ-Cl)]2Cl2}n. Structures of the selected complexes 4 and 5 were confirmed by single crystal X-ray crystallography. The mechanism of the observed copper(II)-assisted hydrolysis of cyclic ureas 3 was elucidated with the aid of quantum chemical calculations.