Effect of N ancillary ligands on the structure, nuclearity and magnetic behavior of Cu(ii)–pyrazolecarboxylate complexes

Abstract

In the absence/presence of different N ancillary ligands, four copper(II)-pyrazolecarboxylate complexes, [Cu(HMPCA)₂(ImH)₂]·2H₂O (1), [Cu₂(MPCA)₂(H₂O)₄] (2), [Cu₂(MPCA)₂(4,4′-bpy)(H₂O)₂]_n·5nH₂O (3) and [Cu₃(MPCA)₃(Phen)₃]₂·2EtOH·15H₂O (4) (H₂MPCA = 5-methyl-1H-pyrazole-3-carboxylic acid, ImH = imidazole, 4,4′-bpy = 4,4′-bipyridine and Phen = 1,10-phenanthroline) were obtained. All complexes have been structurally characterized. Compounds 2 and 3 containing the same bis(μ-pyrazolato)dicopper(II) planes range from dinuclear to 1D polymer. Trinuclear complex 4 contains the first reported cyclic-trinuclear copper(II)–pyrazolato structure without any μ₃ ligand core. Magnetic susceptibility data show that complexes 2–4 exhibit antiferromagnetic couplings between the adjacent magnetic centers.