New cobalt(II) and nickel(II) complexes of 2-hydroxy-benzyl derivatives of 4-aminoantipyrine

The complexes [Co(HL2)2]·H2O·3CH3OH (3), [Ni(HL1)2]·4H2O·CH3OH (4) and [Ni(HL2)2]·4H2O·CH3OH (5) with 4-((2-hydroxybenzyl)amino)-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one (H2L1, 1) and 4-((5-bromo-2-hydroxybenzyl)amino)-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one (H2L2, 2) ligands were synthesized and characterized by elemental analysis, ESI-MS, IR spectroscopy and X-ray single-crystal analysis. Compounds 1 and 2 were prepared by the Schiff condensation of 4-aminoantipyrine and salicylaldehyde or its 5-bromo-derivative with subsequent reduction. 1 and 2 were characterized by elemental analysis, ESI-MS, IR, 1H and 13C NMR spectroscopies. All the complexes 3–5 have a metal-to-ligand ratio of 1:2, the ligands being coordinated in the ONO mode, while the Co(II) and Ni(II) ions display a distorted octahedral geometry. In the solid state, 3–5 are arranged as 1D supramolecular chains through H-bonded water–methanol clusters placed in the voids of the metal-organic units.

Graphical abstractThe preparation and characterization of new derivatives of 4-aminoantipyrine and their Co(II) and Ni(II) complexes are reported.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Co(II) and Ni(II) complexes with substituted 4-(2-hydroxybenzyl)amino)-pyrazol-3-one. ► Ligands act as tridentate ONO donors. ► Co(II) and Ni(II) ion display distorted octahedral geometry.