Supramolecular structure formation of molecular copper(II)methylsalicylate complexes with nicotinamide or methylnicotinamide – Crystal structure and spectral properties

Abstract

As the systematic investigation of salicylatocopper complexes with nicotinamide derivatives the preparation, characterization and X-ray structure determination of four new molecular copper(II) complexes with x-methylsalicylate anion (x-Mesal−) and nicotinamide (nia) or N-methylnicotinamide (mna) are reported. The molecular complexes [Cu(5-Mesal)2(nia)2] (1), [Cu(3-Mesal)2(nia)2] (2) build up 2-D supramolecular structures of different character. The ladder-type supramolecular structure of (1) is formed by the head-to-head H-bonds of neighbouring carboxamide groups, while the supramolecular structure of (2) is formed by NH⋯O H-bonds of carboxamide groups into 1-D chain that are by the additional HH⋯O H-bonds of NH carboxamide and the carboxylate group oxygen atoms linked to 2-D layers. The centrosymmetrical crystal molecular structure of [Cu(4-Mesal)2(mna)2(H2O)2]⋅2EtOH (3) or [Cu(5-Mesal)2(mna)2(H2O)2]⋅2MeOH (4) are forming 1-D supramolecular chains that involve the methylcarboxamide NH group, the crystalosolvate alcohol OH group, the coordinated water molecule OH bond and oxygen atom of neighbouring complex molecule. The coordination polyhedron symmetry corresponds with the isotropic character of EPR spectra of (1) and (2) while the EPR spectrum of (4) is of axial symmetry.