Exploration of Intramolecular Interactions and Single-Molecule Magnetic Behaviors in MIII4LnIII2 (M = Fe, Ga; Ln = Dy, Y) Complexes

Three hexanuclear heterometallic complexes, namely, [M(4)(III)Ln(2)(III)(mu(3)-OH)(2)(mdea)(4)(C6H5CO2)(6)(N-3)(2)]center dot H2O [M = Fe, Ln = Y (1); M = Ga, Ln = Dy (2); and M = Fe, Ln = Dy (3), mdeaH(2) = methyldiethanolamine], have been synthesized and characterized. The results of single-crystal X-ray diffraction analysis showed that compounds 1-3 contain the identical {M(4)(III)Ln(2)(III)} core (M = Ga, Fe; Ln = Y, Dy). DC magnetic susceptibility measurements indicated that the magnetic interactions between Fe-III centers are antiferromagnetic, whereas the exchange couplings between the Fe-III and Dy-III centers are ferromagnetic. AC magnetic susceptibility measurements revealed that (Ga4Dy2III)-Dy-III 2 and (Fe4Dy2III)-Dy-III 3 displayed single-molecule magnetic behaviors. To the best of our knowledge, an energy barrier of 125.3 K for (Ga4Dy2III)-Dy-III compound 2 is the highest energy barrier among all reported Ga-III-Dy-III single-molecule magnets. After replacing the diamagnetic Ga-III centers with paramagnetic Fe-III centers, magnetic relaxation occurs at a 0 dc field, indicating that quantum tunneling of magnetization can be inhibited by weak ferromagnetic interactions between Fe-III and Dy-III ions.

Automated summary

Three hexanuclear heterometallic complexes have been synthesized and characterized. Two of them show single-molecule magnetic behaviors. The magnetic properties and structures of these complexes have been studied through magnetic susceptibility measurements and X-ray diffraction analysis.