Magnetic Properties of Hexanuclear Lanthanide(III) Clusters Incorporating a Central μ₆-Carbonate Ligand Derived from Atmospheric CO₂ Fixation

Three isostructural hexanuclear lanthanide­(III) clusters are reported (Ln^III = Gd, Tb, and Dy). The metallic core of each complex displays an unusual arrangement of ions, which is stabilized by a μ₆-carbonate ligand. Magnetic studies show that the Ln^III ions in each compound are weakly exchange coupled, with the Tb and Dy analogues displaying single-molecule-magnet behavior

Magnetic Properties of Hexanuclear Lanthanide(III) Clusters Incorporating a Central μ₆-Carbonate Ligand Derived from Atmospheric CO₂ Fixation

Three isostructural hexanuclear lanthanide­(III) clusters are reported (Ln^III = Gd, Tb, and Dy). The metallic core of each complex displays an unusual arrangement of ions, which is stabilized by a μ₆-carbonate ligand. Magnetic studies show that the Ln^III ions in each compound are weakly exchange coupled, with the Tb and Dy analogues displaying single-molecule-magnet behavior

Magnetic Properties of Hexanuclear Lanthanide(III) Clusters Incorporating a Central μ₆-Carbonate Ligand Derived from Atmospheric CO₂ Fixation

Three isostructural hexanuclear lanthanide­(III) clusters are reported (Ln^III = Gd, Tb, and Dy). The metallic core of each complex displays an unusual arrangement of ions, which is stabilized by a μ₆-carbonate ligand. Magnetic studies show that the Ln^III ions in each compound are weakly exchange coupled, with the Tb and Dy analogues displaying single-molecule-magnet behavior

Magnetic Properties of Hexanuclear Lanthanide(III) Clusters Incorporating a Central μ₆-Carbonate Ligand Derived from Atmospheric CO₂ Fixation

Three isostructural hexanuclear lanthanide­(III) clusters are reported (Ln^III = Gd, Tb, and Dy). The metallic core of each complex displays an unusual arrangement of ions, which is stabilized by a μ₆-carbonate ligand. Magnetic studies show that the Ln^III ions in each compound are weakly exchange coupled, with the Tb and Dy analogues displaying single-molecule-magnet behavior

Single-Molecule Magnetism in Three Related {Co^III₂Dy^III₂}‑Acetylacetonate Complexes with Multiple Relaxation Mechanisms

Three new heterometallic complexes with formulas ­of ­[Dy^III₂­Co^III₂­(OMe)₂­(teaH)₂­(acac)₄­(NO₃)₂]­ (<b>1</b>),­ [Dy^III₂Co^III₂­(OH)₂­(teaH)₂­(acac)₄­(NO₃)₂]­·4H₂O (<b>2</b>), and [Dy^III₂­Co^III₂­(OMe)₂­(mdea)₂­(acac)₄­(NO₃)₂] (<b>3</b>) were characterized by single-crystal X-ray diffraction and by dc and ac magnetic susceptibility measurements. All three complexes have an identical “butterfly”-type metallic core that consists of two Dy^III ions occupying the “body” position and two diamagnetic low-spin Co^III ions occupying the outer “wing-tips”. Each complex displays single-molecule magnet (SMM) behavior in zero applied magnetic field, with thermally activated anisotropy barriers of 27, 28, and 38 K above 7.5 K for <b>1</b>–<b>3</b>, respectively, as well as observing a temperature-independent mechanism of relaxation below 5 K for <b>1</b> and <b>2</b> and at 3 K for <b>3</b>, indicating fast quantum tunneling of magnetization (QTM). A second, faster thermally activated relaxation mechanism may also be active under a zero applied dc field as derived from the Cole–Cole data. Interestingly, these complexes demonstrate further relaxation modes that are strongly dependent upon the application of a static dc magnetic field. Dilution experiments that were performed on <b>1</b>, in the {Y^III₂Co^III₂} diamagnetic analog, show that the slow magnetic relaxation is of a single-ion origin, but it was found that the neighboring ion also plays an important role in the overall relaxation dynamics

Single-Molecule Magnetism in Three Related {Co^III₂Dy^III₂}‑Acetylacetonate Complexes with Multiple Relaxation Mechanisms

Three new heterometallic complexes with formulas ­of ­[Dy^III₂­Co^III₂­(OMe)₂­(teaH)₂­(acac)₄­(NO₃)₂]­ (<b>1</b>),­ [Dy^III₂Co^III₂­(OH)₂­(teaH)₂­(acac)₄­(NO₃)₂]­·4H₂O (<b>2</b>), and [Dy^III₂­Co^III₂­(OMe)₂­(mdea)₂­(acac)₄­(NO₃)₂] (<b>3</b>) were characterized by single-crystal X-ray diffraction and by dc and ac magnetic susceptibility measurements. All three complexes have an identical “butterfly”-type metallic core that consists of two Dy^III ions occupying the “body” position and two diamagnetic low-spin Co^III ions occupying the outer “wing-tips”. Each complex displays single-molecule magnet (SMM) behavior in zero applied magnetic field, with thermally activated anisotropy barriers of 27, 28, and 38 K above 7.5 K for <b>1</b>–<b>3</b>, respectively, as well as observing a temperature-independent mechanism of relaxation below 5 K for <b>1</b> and <b>2</b> and at 3 K for <b>3</b>, indicating fast quantum tunneling of magnetization (QTM). A second, faster thermally activated relaxation mechanism may also be active under a zero applied dc field as derived from the Cole–Cole data. Interestingly, these complexes demonstrate further relaxation modes that are strongly dependent upon the application of a static dc magnetic field. Dilution experiments that were performed on <b>1</b>, in the {Y^III₂Co^III₂} diamagnetic analog, show that the slow magnetic relaxation is of a single-ion origin, but it was found that the neighboring ion also plays an important role in the overall relaxation dynamics

Single-Molecule Magnetism in Three Related {Co^III₂Dy^III₂}‑Acetylacetonate Complexes with Multiple Relaxation Mechanisms

Three new heterometallic complexes with formulas ­of ­[Dy^III₂­Co^III₂­(OMe)₂­(teaH)₂­(acac)₄­(NO₃)₂]­ (<b>1</b>),­ [Dy^III₂Co^III₂­(OH)₂­(teaH)₂­(acac)₄­(NO₃)₂]­·4H₂O (<b>2</b>), and [Dy^III₂­Co^III₂­(OMe)₂­(mdea)₂­(acac)₄­(NO₃)₂] (<b>3</b>) were characterized by single-crystal X-ray diffraction and by dc and ac magnetic susceptibility measurements. All three complexes have an identical “butterfly”-type metallic core that consists of two Dy^III ions occupying the “body” position and two diamagnetic low-spin Co^III ions occupying the outer “wing-tips”. Each complex displays single-molecule magnet (SMM) behavior in zero applied magnetic field, with thermally activated anisotropy barriers of 27, 28, and 38 K above 7.5 K for <b>1</b>–<b>3</b>, respectively, as well as observing a temperature-independent mechanism of relaxation below 5 K for <b>1</b> and <b>2</b> and at 3 K for <b>3</b>, indicating fast quantum tunneling of magnetization (QTM). A second, faster thermally activated relaxation mechanism may also be active under a zero applied dc field as derived from the Cole–Cole data. Interestingly, these complexes demonstrate further relaxation modes that are strongly dependent upon the application of a static dc magnetic field. Dilution experiments that were performed on <b>1</b>, in the {Y^III₂Co^III₂} diamagnetic analog, show that the slow magnetic relaxation is of a single-ion origin, but it was found that the neighboring ion also plays an important role in the overall relaxation dynamics

Single-Molecule Magnetism in Three Related {Co^III₂Dy^III₂}‑Acetylacetonate Complexes with Multiple Relaxation Mechanisms

Three new heterometallic complexes with formulas ­of ­[Dy^III₂­Co^III₂­(OMe)₂­(teaH)₂­(acac)₄­(NO₃)₂]­ (<b>1</b>),­ [Dy^III₂Co^III₂­(OH)₂­(teaH)₂­(acac)₄­(NO₃)₂]­·4H₂O (<b>2</b>), and [Dy^III₂­Co^III₂­(OMe)₂­(mdea)₂­(acac)₄­(NO₃)₂] (<b>3</b>) were characterized by single-crystal X-ray diffraction and by dc and ac magnetic susceptibility measurements. All three complexes have an identical “butterfly”-type metallic core that consists of two Dy^III ions occupying the “body” position and two diamagnetic low-spin Co^III ions occupying the outer “wing-tips”. Each complex displays single-molecule magnet (SMM) behavior in zero applied magnetic field, with thermally activated anisotropy barriers of 27, 28, and 38 K above 7.5 K for <b>1</b>–<b>3</b>, respectively, as well as observing a temperature-independent mechanism of relaxation below 5 K for <b>1</b> and <b>2</b> and at 3 K for <b>3</b>, indicating fast quantum tunneling of magnetization (QTM). A second, faster thermally activated relaxation mechanism may also be active under a zero applied dc field as derived from the Cole–Cole data. Interestingly, these complexes demonstrate further relaxation modes that are strongly dependent upon the application of a static dc magnetic field. Dilution experiments that were performed on <b>1</b>, in the {Y^III₂Co^III₂} diamagnetic analog, show that the slow magnetic relaxation is of a single-ion origin, but it was found that the neighboring ion also plays an important role in the overall relaxation dynamics

A Family of {Cr^III₂Ln^III₂} Butterfly Complexes: Effect of the Lanthanide Ion on the Single-Molecule Magnet Properties

We report the synthesis of several heterometallic 3d–4f complexes which result from the replacement of the Dy^III ions in the [Cr^III₂Dy^III₂­(OMe)₂­(mdea)₂­(O₂CPh)₄­(NO₃)₂] single-molecule magnet (SMM) by the trivalent Pr, Nd, Gd, Tb, Ho, and Er lanthanide ions. The parent {Cr₂Dy^III₂} compound displayed an anisotropy barrier to magnetization reversal of 53 cm^–1, with magnetic hysteresis observed up to 3.5 K and with large coercive fields at low temperatures (2.7 T at 1.8 K). Magnetic studies for the new complexes revealed significantly different static and dynamic magnetic behavior in comparison to the parent {Cr^III₂Dy^III₂} complex. When Ln^III = Pr, a complete loss of SMM behavior is found, but when Ln^III = Nd or Er, frequency-dependent tails in the out-of-phase susceptibility at low temperatures are observed, indicative of slow magnetic relaxation, but with very small anisotropy barriers and fast relaxation times. When Ln^III = Tb and Ho, SMM behavior is clearly revealed with anisotropy barriers of 44 and 36 cm^–1, respectively. Magnetic hysteresis is also observed up to 2.5 and 1.8 K (0.003 T/s) for the Tb and Ho complexes, respectively. A large loss of the magnetization is, however, observed at zero-field, and as a result, the large coercivity which is present in the {Cr₂Dy₂} example is lost. The {Cr₂Tb₂} and {Cr₂Ho₂} complexes are rare examples of Tb- and Ho-based SMMs which reveal both slow relaxation in the absence of a static dc field (ac susceptibility) and open hysteresis loops above 1.8 K

A Family of {Cr^III₂Ln^III₂} Butterfly Complexes: Effect of the Lanthanide Ion on the Single-Molecule Magnet Properties

We report the synthesis of several heterometallic 3d–4f complexes which result from the replacement of the Dy^III ions in the [Cr^III₂Dy^III₂­(OMe)₂­(mdea)₂­(O₂CPh)₄­(NO₃)₂] single-molecule magnet (SMM) by the trivalent Pr, Nd, Gd, Tb, Ho, and Er lanthanide ions. The parent {Cr₂Dy^III₂} compound displayed an anisotropy barrier to magnetization reversal of 53 cm^–1, with magnetic hysteresis observed up to 3.5 K and with large coercive fields at low temperatures (2.7 T at 1.8 K). Magnetic studies for the new complexes revealed significantly different static and dynamic magnetic behavior in comparison to the parent {Cr^III₂Dy^III₂} complex. When Ln^III = Pr, a complete loss of SMM behavior is found, but when Ln^III = Nd or Er, frequency-dependent tails in the out-of-phase susceptibility at low temperatures are observed, indicative of slow magnetic relaxation, but with very small anisotropy barriers and fast relaxation times. When Ln^III = Tb and Ho, SMM behavior is clearly revealed with anisotropy barriers of 44 and 36 cm^–1, respectively. Magnetic hysteresis is also observed up to 2.5 and 1.8 K (0.003 T/s) for the Tb and Ho complexes, respectively. A large loss of the magnetization is, however, observed at zero-field, and as a result, the large coercivity which is present in the {Cr₂Dy₂} example is lost. The {Cr₂Tb₂} and {Cr₂Ho₂} complexes are rare examples of Tb- and Ho-based SMMs which reveal both slow relaxation in the absence of a static dc field (ac susceptibility) and open hysteresis loops above 1.8 K