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 [Co II Co III (HL 2 ) 2 (L 1 )] [L 1 H = 2‐hydroxy‐1‐naphthaldehyde ( 1 ), o ‐vanillin ( 2 ), and salicylaldehyde ( 3 )] have been synthesized successfully using Schiff base (LH 4 ) ligand. The complexes were characterized by single‐crystal XRD, powder XRD, IR, and UV–Vis analyses. The Co II 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.