Magnetic relaxation in a Co(ii) chain complex: synthesis, structure, and DFT computational coupling constant

Abstract

A novel high-spin Co(II) complex, named [Co^II₂(μ-L₁)(μ-L₂)(μ-Cl)Cl]_n (1), was achieved through the reaction of Co(II) salts with two kinds of pyrazolate ligands (HL₁ = 2-(5-methyl-1H-pyrazol-3-yl) pyridine; HL₂ = 2-(5-methyl-4H-1,2,4-triazol-3-yl)phenol) using a solvothermal method. Structurally, two types of Co(II) ions, octahedral and tetrahedral, bridged by three types of linkers (μ-Cl, μ-(N–N), μ-O), extend into 1D chains. Additionally, the interchain connections are weak, facilitating the occurrence of single-chain magnetic behavior. Magnetically, considerable frequency dependence of slow magnetic relaxation is observed below 5 K and the compound behaves like a single-chain magnet. Both the simulation of the coupling constant from the χ_MT vs. T curve and DFT computations reveal that the μ-O linker in the Co₂O₂ system transmits ferromagnetic coupling.