A Family of Binuclear Dysprosium(III) Radical Compounds with Magnetic Relaxation in ON and OFF States

作者：Han, Tian; Shi, Wei^*; Zhang, Xiao-Ping; Li, Lei-Lei; Cheng, Peng

来源：Inorganic Chemistry, 2012, 51(23): 13009-13016.

DOI：10.1021/ic3021244

• SINGLE-MOLECULE-MAGNET
• CONTINUOUS SYMMETRY MEASURES
• SHARING DY-3 TRIANGLES
• ANISOTROPIC BARRIER
• CHAIN MAGNETS
• BEHAVIOR
• EXCHANGE
• COMPLEX
• AGGREGATE
• POLYHEDRA

Four binuclear dysprosium compounds incorporating the radical ligand 2-(4-oxidopyridyl)-4,4,5,5-tetramethylimidazolin-1-oxyl-3-oxide (PyNONIT) have been successfully synthesized under appropriate conditions. Centrosymmetric bimetallic Dy2O2 cores in all of the compounds through double-mu(2)-oxygen atoms of the N-oxide groups are realized in a metal-radical approach for the first time. Dimers 1 and 2, of the same formula {[Dy(hfac)(3)(PyNONIT)](2)}(2) (hfac = hexafluoroacetylacetonate) but obtained by different methods, which contain almost identical local symmetry of D-4d and Dy-(O)(2)-Dy bridging fashion, however, display no out-of-phase alternating-current (ac) signal for 1 and slow relaxation of the magnetization for 2 corresponding to the difference of the crystal packing mode. The adduct ([Dy(hfac)(3)(PyNONIT)](2)[Dy-0.5(hfac)(1.5)(H2O)](2)) (3) consists of two items, the dimer [Dy(hfac)(3)(PyNONIT)](2) and the monomer [Dy(hfac)(3)(H2O)(2)], where the symmetry of Dy-III ion in Dy2O2 decreases to D-2d, showing slow relaxation of the magnetization at lower temperature. Interestingly, a moisture-mediated reversible solid transformation between 1 and ([Dy(hfac)(3)(H2O)(PyNONIT)](2)) (4) has been investigated. Spongelike 1 can undergo a transition from eight to nine coordination at room temperature through hydration. A different coordination field is mostly responsible for no ac signal noticed for 4. The structural diversity of the Dy-2 family provides an opportunity to expand the investigation on 4f single molecule magnets. Approaches that the relaxation of the supramolecular dimer can be tuned to ON and OFF states modulated by the packing mode and ligand field are presented.

• 出版日期2012-12-3
• 单位南开大学