A Dy2 Complex Constructed by TCNQ·− Radical Anions with Slow Magnetic Relaxation Behavior

A centrosymmetric dinuclear complex, [Dy2(H2dapp)2(μ-OH)2(H2O)2]·4TCNQ·2CH3OH, was synthesized using the TCNQ·− radical anion (TCNQ = 7,7,8,8-tetracyanoquino-dimethane) and pentadentate nitrogen-containing Schiff base ligand (H2dapp = 2,6-diacetylpyridine)-bis(2-pyridylhydrazone). In the Dy2 dimer, the two DyIII ions adopt eight-coordinated geometries intermediate between D4d and D2d symmetries, linked by two OH− groups, with ferromagnetic Dy-Dy interactions. The TCNQ·− radical anions are uncoordinated, and they pack tightly into antiparamagnetic dimers to balance the system charge. Under zero field, weak magnetic relaxation was observed, with an approximate Δeff = 2.82 K and τ0 = 6.88 × 10−6 s. This might be attributed to the short intermolecular Dy···Dy distance of 7.97 Å, which could enhance intermolecular dipolar interactions and quantum tunneling of magnetization (QTM).