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

A novel high-spin Co(II) complex, named (Co-2(II)(mu-L-1)(mu-L-2)(mu-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 (mu-Cl, mu-(N-N), mu-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 T-chi M vs. T curve and DFT computations reveal that the mu-O linker in the Co2O2 system transmits ferromagnetic coupling.

Automated summary

A novel high-spin Co(II) complex has been synthesized using a solvothermal method, featuring Co(II) ions in octahedral and tetrahedral coordination bridged by mu-Cl, mu-(N-N), and mu-O linkers forming 1D chains. The compound exhibits single-chain magnetic behavior at low temperatures, with the mu-O linker transmitting ferromagnetic coupling according to both simulation and DFT computations.