Sterically-controlled nuclearity in new copper(II) complexes with di-compartmental ligands: Formation of antiferromagnetically coupled angular trimer and mononuclear inclusion complex

Two new copper(II) complexes, [Cu3(L1)2(H2O)2](ClO4)2 (1) and [CuL2⊂⊂ (H2O)] (2) have been derived from two di-compartmental Schiff base ligands H2L1 and H2L2, respectively. Depending on slight modification of the substituent group of the potentially N2O4 donor ligands, tri- and mononuclear structures are obtained, which have been confirmed by single-crystal X-ray diffraction studies. Both complexes have been characterized by elemental analysis, IR, UV–vis and EPR spectroscopy. Complex 1 consists of an angular trinuclear array of copper ions, while complex 2 consists of a mononuclear copper center. Variable temperature magnetic susceptibility measurements have been performed to investigate the magnetic behaviour of complex 1 and the result indicates a strong antiferromagnetic exchange interaction (J = −120.1(2) cm−1) between the adjacent copper(II) centers through two double μ2-phenoxo bridges. Complex 2 is a mononuclear inclusion compound encapsulating one water molecule in the vacant external compartment of the ligand through hydrogen-bonding interactions.

The variation in the coordination properties of two N2O4 donor di-compartmental Schiff bases, H2L1 and H2L2 leads to the formation of two structurally different copper(II) complexes, 1 and 2, respectively. Complex 1 is a doubly phenoxo-bridged trinuclear complex with an unusual angular configuration showing strong antiferromagnetic interaction. In contrast, 2 is a mononuclear inclusion complex, exhibiting encapsulation of water molecule.Figure optionsDownload as PowerPoint slide