Geometrievermittelte Anisotropieverstärkung: Zugang zu molekularen Magneten mit hoher Blocking‐Temperatur

Starting from a polyimido sulfonate the four-coordinate, N,N'-chelated Co(II) complex [Co{(NtBu)3 SMe}2 ] (1) was synthesized, and its molecular structure was elucidated by single-crystal X-ray structural analysis. The acute N-Co-N bite angle imposed by the N,N'-chelating ligand (NtBu)3 SMe(-) leads to pronounced C2v distortion of the tetrahedral coordination environment and thus to high anisotropy of the Co(II) ion (D≈-58 cm(-1) ), favorable for single-molecule-magnet (SMM) properties. Magnetic measurements revealed a high barrier to spin reversal (Ueff =75 cm(-1) ) that gives rise to the observation of slow relaxation of the magnetization in zero field and a hysteresis loop at 2 K for this unique complex.

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Triimidosulfonates as Acute Bite‐Angle Chelates: Slow Relaxation of the Magnetization in Zero Field and Hysteresis Loop of a Co^II Complex

Carl

Demeshko

Meyer

et al. 2015

Chemistry A European J

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Pentagonal Bipyramid Fe^II Complexes: Robust Ising‐Spin Units towards Heteropolynuclear Nanomagnets

Bar

Gogoi

Pichon

et al. 2017

Chemistry A European J

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Pentagonal bipyramid Fe complexes have been investigated to evaluate their potential as Ising-spin building units for the preparation of heteropolynuclear complexes that are likely to behave as single-molecule magnets (SMMs). The considered monometallic complexes were prepared from the association of a divalent metal ion with pentadentate ligands that have a 2,6-diacetylpyridine bis(hydrazone) core (H L ). Their magnetic anisotropy was established by magnetometry to reveal their zero-field splitting (ZFS) parameter D, which ranged between -4 and -13 cm and was found to be modulated by the apical ligands (ROH versus Cl). The alteration of the D value by N-bound axial CN ligands, upon association with cyanometallates, was also assessed for heptacoordinated Fe as well as for related Ni and Co derivatives. In all cases, N-coordinated cyanide ligands led to large magnetic anisotropy (i.e., -8 to -18 cm for Fe and Ni, +33 cm for Co). Ab initio calculations were performed on three Fe complexes, which enabled one to rationalize the role of the ligand on the nature and magnitude of the magnetic anisotropy. Starting from the pre-existing heptacoordinated complexes, a series of pentanuclear compounds were obtained by reactions with paramagnetic [W(CN) ] . Magnetic studies revealed the occurrence of ferromagnetic interactions between the spin carriers in all the heterometallic systems. Field-induced slow magnetic relaxation was observed for mononuclear Fe complexes (U /k up to 53 K (37 cm ), τ =5×10 s), and SMM behavior was evidenced for a heteronuclear [Fe W ] derivative (U /k =35 K and τ =4.6 10 s), which confirmed that the parent complexes were robust Ising-type building units. High-field EPR spectroscopic investigation of the ZFS parameters for a Ni derivative is also reported.

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Spectroscopic Studies of the Magnetic Excitation and Spin‐Phonon Couplings in a Single‐Molecule Magnet

Stavretis

Moseley

Fei

et al. 2019

Chemistry A European J

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Large separations between ground and excited magnetic states in single‐molecule magnets (SMMs) are desirable to reduce the likelihood of spin reversal in the molecules. Spin‐phonon coupling is a process leading to magnetic relaxation. Both the reversal and coupling, making SMMs lose magnetic moments, are undesirable. However, direct determination of large magnetic states separations (>45 cm−1) is challenging, and few detailed investigations of the spin‐phonon coupling have been conducted. The magnetic separation in [Co(12‐crown‐4)2](I3)2(12‐crown‐4) (1) is determined and its spin‐phonon coupling is probed by inelastic neutron scattering (INS) and far‐IR spectroscopy. INS, using oriented single crystals, shows a magnetic transition at 49.4(1.0) cm−1. Far‐IR reveals that the magnetic transition and nearby phonons are coupled, a rarely observed phenomenon, with spin‐phonon coupling constants of 1.7–2.5 cm−1. The current work spectroscopically determines the ground–excited magnetic states separation in an SMM and quantifies its spin‐phonon coupling, shedding light on the process causing magnetic relaxation.

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Geometrievermittelte Anisotropieverstärkung: Zugang zu molekularen Magneten mit hoher Blocking‐Temperatur

Cited by 5 publications

References 18 publications

Triimidosulfonates as Acute Bite‐Angle Chelates: Slow Relaxation of the Magnetization in Zero Field and Hysteresis Loop of a Co^II Complex

Triimidosulfonates as Acute Bite‐Angle Chelates: Slow Relaxation of the Magnetization in Zero Field and Hysteresis Loop of a Co^II Complex

Pentagonal Bipyramid Fe^II Complexes: Robust Ising‐Spin Units towards Heteropolynuclear Nanomagnets

Spectroscopic Studies of the Magnetic Excitation and Spin‐Phonon Couplings in a Single‐Molecule Magnet

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Geometrievermittelte Anisotropieverstärkung: Zugang zu molekularen Magneten mit hoher Blocking‐Temperatur

Cited by 5 publications

References 18 publications

Triimidosulfonates as Acute Bite‐Angle Chelates: Slow Relaxation of the Magnetization in Zero Field and Hysteresis Loop of a CoII Complex

Triimidosulfonates as Acute Bite‐Angle Chelates: Slow Relaxation of the Magnetization in Zero Field and Hysteresis Loop of a CoII Complex

Pentagonal Bipyramid FeII Complexes: Robust Ising‐Spin Units towards Heteropolynuclear Nanomagnets

Spectroscopic Studies of the Magnetic Excitation and Spin‐Phonon Couplings in a Single‐Molecule Magnet

Contact Info

Product

Resources

About

Triimidosulfonates as Acute Bite‐Angle Chelates: Slow Relaxation of the Magnetization in Zero Field and Hysteresis Loop of a Co^II Complex

Triimidosulfonates as Acute Bite‐Angle Chelates: Slow Relaxation of the Magnetization in Zero Field and Hysteresis Loop of a Co^II Complex

Pentagonal Bipyramid Fe^II Complexes: Robust Ising‐Spin Units towards Heteropolynuclear Nanomagnets