Magneto-Structural Correlations in a Family of FeIIReIV(CN)2 Single-Chain Magnets: Density Functional Theory and Ab Initio Calculations

Until now, the expressions of the anisotropic energy barriers Δξ and ΔA, using the uniaxial magnetic anisotropy D, the intrachain coupling strength J, and the high-spin ground state S for single-chain magnets (SCMs) in the intermediate region between the Ising and the Heisenberg limits, were unknown. To explore this relationship, we used density functional theory and ab initio methods to obtain expressions of Δξ and ΔA in terms of D, J, and S of six R4FeII–ReIVCl4(CN)2 (R = diethylformamide (1), dibutylformamide (2), dimethylformamide (3), dimethylbutyramide (4), dimethylpropionamide (5), and diethylacetamide (6)) SCMs in the intermediate region. The ΔA value for compounds 1–3 was very similar to the magnetic anisotropic energy of a single FeII, while the value of Δξ was predicted using the exchange interaction of FeII with the neighboring ReIV, which could be expressed as 2JSReSFe. Similar to compounds 1–3, the anisotropy energy barrier ΔA of compounds 4 and 5 was also equal to (Di – Ei)SFe2, but the cor...