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

A novel high-spin Co( ii ) complex, named [Co II 2 (μ-L 1 )(μ-L 2 )(μ-Cl)Cl] n ( 1 ), was achieved through the reaction of Co( ii ) salts with two kinds of pyrazolate ligands (HL 1 = 2-(5-methyl-1 H -pyrazol-3-yl) pyridine; HL 2 = 2-(5-methyl-4 H -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 M T vs. T curve and DFT computations reveal that the μ-O linker in the Co 2 O 2 system transmits ferromagnetic coupling. We report a homospin non-solvated Co II chain compound constructed by two similar tridentate ligands and chloride ions, which displays slow magnetic relaxation below 5 K.