Copper(II) complexes with 1,5-bis(2-hydroxybenzaldehyde)carbohydrazone

The acid–base properties of 1,5-bis(2-hydroxybenzaldehyde)carbohydrazone (H4L) and its thioanalogue 1,5-bis(2-hydroxybenzaldehyde)thiocarbohydrazone (H4LS) have been studied experimentally by pH-potentiometry and UV–Vis spectrophotometry and theoretically by using DFT methods. Copper(II) complexes [Cu2(HL)(DMSO)2(H2O)]NO3·H2O (1), [{Cu2(HL)(DMF)(H2O)}n][{Cu2(HL)(DMF)NO3}n](NO3)n (2), [Cu2(HL)(DMF)2(H2O)]HSO4·H2O (3), [Cu2(HL)(DMF)2(H2O)][Cu2(HL)(SO4)(H2O)(DMF)2]·2H2O (4) and [Cu4(HL)2(HSO4)(DMF)2]HSO4 (5), where H4L = 1,5-bis(2-hydroxybenzaldehyde)carbohydrazone, have been synthesised. Complexes 1–3 have been characterised by elemental analysis, IR spectroscopy, ESI mass spectrometry, cyclic voltammetry, magnetic susceptibility measurements and X-ray diffraction, while 4 and 5 only by X-ray crystallography. X-ray diffraction revealed that the ditopic triply deprotonated ligand possesses two binding sites able to accommodate transition metal ions, namely ONN and ONO. Magnetic measurements showed antiferromagnetic interactions between copper(II) centres.

Graphical abstractThe acid–base properties of 1,5-bis(2-hydroxybenzaldehyde)carbohydrazone and its thioanalogue have been studied experimentally and by DFT methods. Five copper(II) complexes with 1,5-bis(2-hydroxybenzaldehyde)carbohydrazone have been synthesised and characterised by X-ray crystallography. The ditopic ligand possesses two binding sites able to accommodate transition metal ions. Magnetic measurements showed antiferromagnetic interactions between copper(II) centres.Figure optionsDownload full-size imageDownload as PowerPoint slide