Ligand-field effect to harness the magnetic anisotropy in a series of mixed valence Co (III)-Co (II) dinuclear complexes

Three mixed valence dinuclear Co (III)-Co (II)-based complexes having general formulae of [CoIICoIII (HL2)2(L1)] [L1H = 2-hydroxy-1-naphthaldehyde (1), o-vanillin (2), and salicylaldehyde (3)] have been synthesized successfully using Schiff base (LH4) ligand. The complexes were characterized by single-crystal XRD, powder XRD, IR, and UV-Vis analyses. The CoII ion with elongated octahedral geometry conferred significant magnetic anisotropy with D values being 64.0(8), 71.1(7), and 52.1(3) cm-1 for 1, 2, and 3, respectively. These complexes exhibited single-molecule magnet behavior with magnetic relaxation occurring mainly through Raman for 1 and 3 whereas direct and Raman for complex 2. The analysis of the static and dynamic magnetic properties was further supported by theoretical calculations using CASSCF/DLPNO-NEVPT2. Three Co (III)-Co (II) mixed valence dinuclear complexes were synthesized and characterized using various techniques. These complexes exhibited elongated octahedral geometry around Co (II) ion, significant magnetic anisotropy, and field-induced single-molecule magnet behavior with magnetization relaxation through Raman, Orbach, and direct processes. The analysis of magnetic properties was complemented by theoretical calculations. image