Dysprosium Single-Molecule Magnets Involving 1,10-Phenantroline-5,6-dione Ligand

Abstract

The two mononuclear complexes of the formula [Dy(tta) 3 (L)] (1) and [Dy(hfac) 3 (L)] (2) (where tta -= 2-thenoytrifluoroacetylacetonate and hfac -= 1,1,1,5,5,5-hexafluoroacetylacetonate) were obtained from the coordination reaction of the Dy(tta) 3 ·2H 2 O or Dy(hfac) 3 ·2H 2 O units with the 1,10-phenantroline-5,6-dione ligand (L). Their structures have been determined by X-ray diffraction studies on single crystals, and they revealed a supramolecular assembly of tetramers through σ-π interactions. Both complexes displayed a Single-Molecule Magnet (SMM) behavior without an external applied magnetic field. Magnetic relaxation happened through Orbach, Raman and Quantum Tunneling of the Magnetization (QTM). Wavefunction theory calculations were realized to rationalize the magnetic properties.

Radical‐Bridged Ln4 Metallocene Complexes with Strong Magnetic Coupling and a Large Coercive Field

“…Thei ntermolecular Dy•••Dy distances vary between 10.202(10) and 10.601(18) (Figure S7). These values are slightly smaller than the largest intramolecular Dy•••Dy distance of 10.715 (18) ,l eading us to believe that the intermolecular interactions may impact the overall magnetic performance.W ith that said, the presence of bridging radical ligands is anticipated to dominate the exchange interactions and provide ag iant-spin vector model intrinsic to the Dy 4 complex. [20,27,37,43] To probe the magnetic interactions between the spin carriers and the potential SMM behavior, we carried out direct current (dc) and alternating current (ac) magnetic susceptibility measurements using aS QUID magnetometer.…”

“…[10] This was achieved through the judicious design of the ligand field around the metal center,w hich stabilizes the lowest degenerate substate with al arge j J z j value that provides significant separations from the higher excited states.T his discovery led to af lurry of lanthanide SMMs with varying nuclearities.P olynuclear lanthanide systems are plagued by the lack of magnetic interactions between the 4f metal ions.H ence,m ononuclear lanthanide SMMs reign supreme magnetic performance owing to their superior magnetic axiality (i.e., axial magnetic anisotropy). [11][12][13][14][15][16][17][18] However,m agnetic axiality must be retained in the ground and excited states,o therwise it would result to the introduction of through-barrier relaxation mechanisms of the magnetization such as quantum tunneling of the magnetization (QTM), Raman and direct. [19] With that said, there is af undamental limit to the intrinsic magnetic properties that could be extracted from as ingle Ln III ion.…”

Radical‐Bridged Ln4 Metallocene Complexes with Strong Magnetic Coupling and a Large Coercive Field

“…[10] This was achieved through the judicious design of the ligand field around the metal center,w hich stabilizes the lowest degenerate substate with al arge j J z j value that provides significant separations from the higher excited states.T his discovery led to af lurry of lanthanide SMMs with varying nuclearities.P olynuclear lanthanide systems are plagued by the lack of magnetic interactions between the 4f metal ions.H ence,m ononuclear lanthanide SMMs reign supreme magnetic performance owing to their superior magnetic axiality (i.e., axial magnetic anisotropy). [11][12][13][14][15][16][17][18] However,m agnetic axiality must be retained in the ground and excited states,o therwise it would result to the introduction of through-barrier relaxation mechanisms of the magnetization such as quantum tunneling of the magnetization (QTM), Raman and direct. [19] With that said, there is af undamental limit to the intrinsic magnetic properties that could be extracted from as ingle Ln III ion.…”

“…Polynuclear lanthanide systems are plagued by the lack of magnetic interactions between the 4 f metal ions. Hence, mononuclear lanthanide SMMs reign supreme magnetic performance owing to their superior magnetic axiality (i.e., axial magnetic anisotropy) [11–18] . However, magnetic axiality must be retained in the ground and excited states, otherwise it would result to the introduction of through‐barrier relaxation mechanisms of the magnetization such as quantum tunneling of the magnetization (QTM), Raman and direct [19] .…”

Redox Modulation of Field-Induced Tetrathiafulvalene-Based Single-Molecule Magnets of Dysprosium

“…The typical oquinone bond lengths are different compared to those in the terminal six-membered rings in bridging In the present article, we propose to focus our attention on the H 2 SQ ligand and its oxidized form Q in the coordination reactions with the Dy(tta) 3 •2H 2 O units. The replacement of the hfac − ancillary anions with tta − is known to change the magnetic performances of the target compound [29,[38][39][40]. Indeed, the resulting X-ray structures of the dinuclear complexes [Dy 2 (tta) 6 (H 2 SQ)] (Dy-H 2 SQ) and [Dy 2 (tta) 6 (Q)]•2CH 2 Cl 2 (Dy-Q) highlighted new coordination spheres around the Dy III compared to those observed for their hfac − parents of formula [Dy 2 (hfac) 6 (H 2 SQ)]•CH 2 Cl 2 and [Dy 2 (hfac) 6 (Q)]) [36] leading to the study of new magnetic properties.…”