Magnetically Active 3d Metal Complexes with 3-Amino-4-Ethoxycarbonylpyrazole

Abstract

Coordination compounds of iron(II) and nickel(II) with 3-amino-4-ethoxycarbonylpyrazole (L), FeL₂A₂ (A = Cl^– (I), \({{{\text{C}}}_{{\text{2}}}}{\text{N}}_{{\text{3}}}^{-}\) (II)), [FeL₂(NCS)₂(H₂O)₂] (III), and NiL₂Br₂ (IV), are synthesized. The compounds are studied by X-ray diffraction analysis, IR spectroscopy, and UV spectroscopy (diffuse reflectance spectra). A single crystal is observed for complex III, and its crystal structure is determined by X-ray structure analysis (СIF file CCDC no. 1857220). It is shown that L coordinates to the metal via the monodentate mode by the N(2) atom of the pyrazole cycle. The study of the temperature dependence µ_eff(Т) in a temperature range of 2–300 K shows exchange interactions of the antiferro- or ferromagnetic character between the M²⁺ ions in the complexes. The type of exchange interactions depends on the composition of the compound.