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).
Wang et al. (Tue,) studied this question.