Hydrogen-bonded supramolecular structures in copper(II) nitrobenzoates with N-methylnicotinamide: synthesis, supramolecular structure, Hirshfeld surface analysis, spectral and DFT study

The synthesis of six new copper(II) nitrobenzoate complexes with N-methylnicotinamide, used as an auxiliary ligand for a supramolecular interaction study, is reported. Crystal structures of six novel compounds [Cu(2-NO(2)bz)(2)(mna)(2)(H2O)(2)] (1), [Cu(2-NO(2)bz)(2)(mna)(2)(H2O)(2)]& BULL;2H(2)O (2), [Cu(3-NO(2)bz)(2)(mna)(2)(H2O)(2)] (3), [Cu(3,5-(NO2)(2)bz)(2)(mna)(2)(H2O)(2)]& BULL;2H(2)O (4), [Cu(4-NO(2)bz)(2)(mna)(2)(H2O)(2)]& BULL;2(4-NO(2)bzH) (5) and [Cu(3,5-(NO2)(2)bz)(2)(mna)(H2O)(3)] (6) (mna = N-methylnicotinamide, 2-NO(2)bz = 2-nitrobenzoate, 3-NO(2)bz = 3-nitrobenzoate, 4-NO(2)bz = 4-nitrobenzoate, 3,5-(NO2)(2)bz = 3,5-dinitrobenzoate) were determined by X-ray analysis. Compounds 1-6 are mononuclear with a tetragonal-bipyramidal geometry around the Cu2+ ion. The molecules of the studied complexes are mostly linked by a combination of N-H horizontal ellipsis O and O-H horizontal ellipsis O hydrogen bonds between N-methylnicotinamide and water molecules into supramolecular hydrogen-bonded coordination chains and networks. Intermolecular interactions in the supramolecular structures were also studied using Hirshfeld surface analysis. In addition, the complexes 1-6 have been characterised by elemental analysis, IR, UV-Vis and EPR spectroscopy. Density functional theory calculations were performed in order to reproduce the EPR magnetic parameters. DFT calculations of the EPR parameters show a good agreement with the experimental results.