Synthesis, Structures, and Single-Molecule Magnetic Properties of Three Dy2 Complexes.

To explore the influences of the subtle structural variations in the ligand backbones on the single-molecule magnetic properties of dinuclear dysprosium(III) complexes, three ligands-H2 L1 (H2 L1 =N1 ,N3 -bis(salicylaldehyde)diethylenetriamine), H2 L2 (H2 L2 =N1 ,N3 -bis(3-methoxysalicylidene)diethylenetriamine), and H2 L3 (H2 L3 =N1 ,N3 -bis(5-chlorosalicyladehyde)diethylenetriamine)-were synthesized and employed to prepare the expected dinuclear dysprosium(III) complexes. The three ligands differ in terms of the substituents at the benzene rings of the salicylaldehyde moieties. The reactions of Dy(NO3 )3 ⋅6 H2 O, pivalic acid, and the ligands H2 L1 , H2 L2 , and H2 L3 generated complexes with the formulae [Dy2 (L1 )2 (piv)2 ] (1), [Dy2 (L2 )2 (piv)2 ] (2), and [Dy2 (L3 )2 (piv)2 ]⋅ 2 MeCN (3), respectively. The purposeful attachment of the functional groups with varied sizes at the benzene rings of the salicylaldehyde backbones resulted in slight differences in the Dy-O-Dy bond angles and the Dy⋅⋅⋅Dy bond lengths in 1-3; consequently, the three complexes exhibited distinct magnetic properties. They all showed slow magnetization relaxation with energy barriers of 40.32 (1), 31.67 (2), and 33.53 K (3). Complete active space self-consistent field (CASSCF) calculations were performed on complexes 1-3 to rationalize the slight discrepancy observed in the magnetic behavior. The calculated results satisfactorily explained the experimental outcomes.