Zero‐field Slow Magnetic Relaxation Behavior of Dy₂ in a Series of Dinuclear {Ln₂} (Ln=Dy, Tb, Gd and Er) Complexes: A Combined Experimental and Theoretical Study

Abstract A series of dinuclear lanthanide(III) complexes having general formulae [Ln 2 L 2 (thd) 4 ] ⋅ 2CH 3 CN {Ln=Dy III ( 1 ), Tb III ( 2 ), Gd III ( 3 ), Er III ( 4 )} were successfully synthesized using Schiff base (E)‐2‐((pyridin‐2‐ylmethylene)amino)phenol (LH) and co‐ligand 2,2,6,6‐Tetramethyl‐3,5‐heptanedione (Hthd). The single crystal XRD data shows that complexes possess a dinuclear planar [Ln 2 ( μ 2 ‐O) 2 ] 4+ core where phenolate oxygen atoms act as bridges between the two Ln III ions, and that the coordination sphere of Ln III with eight coordination has distorted trigonal dodecahedron geometry. The magnetic analysis shows complex 1 is a single molecule magnet having a zero‐field effective energy barrier ( U eff ) of 54.02 K and relaxation time of τ o =4.45×10 −6 s. Field‐induced SMM behavior has been observed for 4 with an effective energy barrier of 26.9 K and τ 0 =2.4×10 −9 s. CASSCF+RASSI‐SO calculations on 1 , 2 and 4 provide deep insight regarding the electronic structure and single‐ion anisotropy of lanthanide ions. Further, using state‐of‐the‐art ab initio calculations, the nature of magnetic anisotropy and magnetic exchange interaction between the Ln III centers is analyzed to shed light on the magnetic dynamics of all the complexes 1 – 4 .