Abstract
The dinucleating fulvalenyl ligand [1,1',3,3'-(C5 t Bu2H2)2]2- (Fvtttt) was used to synthesize the dimetallic dysprosocenium cation [{Dy(η5-Cp*)}2(μ-BH4)(η5:η5-Fvtttt)]+ (3) as the salt of [B(C6F5)4]- (Cp* = C5Me5). Compound [3][B(C6F5)4] was obtained using a method in which the double half-sandwich complex [{Dy(BH4)2(THF)}2(Fvtttt)] (1) was reacted with KCp* to give the double metallocene [{Dy(Cp*)(μ-BH4)}2(Fvtttt)] (2), followed by removal of a bridging borohydride ligand upon addition of [(Et3Si)2(μ-H)][B(C6F5)4]. The dimetallic fulvalenyl complexes 1-3 give rise to single-molecule magnet (SMM) behaviour in zero applied field, with the effective energy barriers of 154(15) cm-1, 252(4) cm-1 and 384(18) cm-1, respectively, revealing a significant improvement in performance across the series. The magnetic properties are interpreted with the aid of ab initio calculations, which show substantial increases in the axiality of the crystal field from 1 to 2 to 3 as a consequence of the increasingly dominant role of the Fvtttt and Cp* ligands, with the barrier height and hysteresis properties being attenuated by the equatorial borohydride ligands. The experimental and theoretical results described in this study furnish a blueprint for the design and synthesis of poly-cationic dysprosocenium SMMs with properties that may surpass those of benchmark systems.
Highlights
Observations of magnetic bistability in structurally wellde ned, monodisperse nanomaterials have stimulated considerable interest in technology based on the quantum properties of atoms and molecules
The experimental and theoretical results described in this study furnish a blueprint for the design and synthesis of poly-cationic dysprosocenium single-molecule magnet (SMM) with properties that may surpass those of benchmark systems
Compound 1 was reacted with two equivalents of potassium pentamethylcyclopentadienide (KCp*) to give the double metallocene [{Dy(h5-Cp*)(m-BH4)}2(h5:h5-Fvtttt)] (2) in which the dysprosium centres are bridged by both borohydride ligands
Summary
Observations of magnetic bistability in structurally wellde ned, monodisperse nanomaterials have stimulated considerable interest in technology based on the quantum properties of atoms and molecules. The demonstration of magnetic memory in single holmium atoms on surfaces has introduced potential for the fabrication of data storage devices with capacities surpassing those of conventional technology.[1,2] Molecule-based magnetic materials offer similar opportunities, accompanied by the advantage that their electronic structure can be tuned using imaginative synthetic chemistry. The magnetic hysteresis properties of single-molecule magnets (SMMs) have been acclaimed as a possible source of novel data storage materials and, while such applications may eventually be possible, certain obstacles must rst be overcome.[6,7,8,9,10] Challenges to the implementation of SMMbased technology include that: (1) all known systems require cooling with cryogens in order to show hysteresis; (2) uniform nano-structuring of SMMs on surfaces is difficult, and; (3) the chemical stability of SMMs throughout surface deposition processes and, subsequently, in a device environment is not guaranteed, regardless of whether or not the bulk material itself is air-sensitive. Encouraging progress has been made, such as the discovery of magnetic hysteresis in an SMM at 80 K,11 i.e. above the boiling point of liquid nitrogen, and elegant surface studies of some SMMs have demonstrated the singlemolecule origins of the hysteresis.[12]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
