Slow magnetization relaxation in a tetrahedrally coordinated mononuclear Co(<scp>ii</scp>) complex exclusively ligated with phenanthroline ligands

Wu, Chen-Ming; Tsai, Jae-En; Lee, Gene‐Hsiang; Yang, En‐Che

doi:10.1039/d0dt03481a

Cited by 5 publications

(4 citation statements)

References 61 publications

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“…In 2020, we employed only 2,9-diphenyl-phenanthroline as the ligand. Without an applied DC magnetic field, no out-of-phase signals were observed . After applying a 1000 G DC magnetic field frequency-dependent out-of-phase signals were observed, reaching a maximum of 6 K. These findings collectively highlight the significance of amide anion ligands in enabling pure nitrogen-coordinated ligands to exhibit SIM behavior.…”

Section: Introductionmentioning

confidence: 67%

“…Instead, among the substituents, the presence of amide anion shows significant differences in D values and the temperature of out-of-phase signals appearing in the absence of an external field. The first row includes three compounds (including 1 ) with substituted Co(II) complexes of bipyridine and phenanthroline . In these three compounds, D values range from −46 to −57 cm –1 .…”

Section: Resultsmentioning

confidence: 99%

“…The first row includes three compounds (including 1) with substituted Co(II) complexes of bipyridine 34 and phenanthroline. 18 In these three compounds, D values range from −46 to −57 cm −1 . However, it is notable that compound 1 is the only one displaying out-of-phase signals without the need for an applied DC magnetic field.…”

Section: ■ Introductionmentioning

confidence: 98%

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Cobalt(II) Single-Ion Magnet Coordinated by Double Deprotonation of 2,2′-Bipyridine-6,6′-diol Ligands

Yang,

Tsai,

Chang

et al. 2024

ACS Omega

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In this study, we synthesized a new Co(II) complex, [NMe 4 ] 2 [Co(bpyO 2 ) 2 ] (1), using deprotonated 2,2′-bipyridine-6,6′-diol ligands (bpyO 2 2−). This compound exhibits a significant zero-field splitting (D) value. The far-infrared magneto spectroscopy and high-frequency and field electron paramagnetic resonance (HFEPR) measurements indicated that compound 1 possesses D = −54.8 cm −1 and E ∼ 0 cm −1 . These findings were subsequently confirmed by other experimental data, including DC magnetic susceptibilities and variable temperature and variable magnetic field reduced magnetizations. Additionally, we conducted a series of AC magnetic susceptibility measurements to investigate the kinetics of magnetization relaxation. Below 6.6 K and under zero external magnetic field, fast quantum tunneling of magnetization (QTM) dominates (∼570 Hz), and temperature-independent out-ofphase signals are observed. Above 8.1 K, temperature-dependent behavior is observed. Furthermore, we examined the AC magnetic susceptibility behavior under external magnetic fields ranging from 300 to 4000 G. The effect of QTM is significantly reduced in the presence of an external magnetic field. Temperature-dependent behavior is primarily governed by Raman relaxation. Through structural analysis of compound 1 and a series of pure nitrogen-coordinated single-ion magnets (SIMs), we propose that the oxo substituents from the double-deprotonated form of the 2,2′-bipyridine-6,6′-diol ligands donate their negative charge to the pyridine ring, forming amido anion sites. This triggers a more pronounced out-of-phase signal than that observed in pure pyridinecoordinated compounds. Moreover, we observed intermolecular interactions, including intermolecular hydrogen bonding, which, to some extent, influenced the slow relaxation of molecules. Therefore, we speculate that the slow relaxation phenomenon of compound 1 may be attributed to the combination of oxo back-donating effects and intermolecular interactions.

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Section: Introductionmentioning

confidence: 67%

Section: Resultsmentioning

confidence: 99%

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Cobalt(II) Single-Ion Magnet Coordinated by Double Deprotonation of 2,2′-Bipyridine-6,6′-diol Ligands

Yang,

Tsai,

Chang

et al. 2024

ACS Omega

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“…14 In 2020, in our laboratory, we initiated a systematic investigation of Co( ii ) SIMs with two ligands that contained four ligating nitrogen atoms. 15 At that time, we reported magnetic field-induced slow-magnetization relaxations at about 6 K. In the current study, we report on the use of this tosylamide bidentate group to boost the temperatures of the out-of-phase signals. By incorporating a series of different geometric pyridine substituents, we observed how they systematically affect the magnetization relaxation mechanism.…”

Section: Introductionmentioning

confidence: 71%

Phonon-induced relaxation mechanisms are changed by a chelating effect in a Co^II single-ion magnet

Lou

Lin

et al. 2022

Dalton Trans.

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Levamisole Based Co(II) Single‐Ion Magnet

Biswas,

Havlicek,

Nemec

et al. 2024

Chemistry An Asian Journal

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A new Co(II) complex, [Co(NCS)2(L)2] (1) has been synthesized based on levamisole (L) as a new ligand. Single‐crystal X‐ray diffraction analyses confirm that the Co(II) ion is having a distorted tetrahedral coordination geometry in the complex. Notably strong intramolecular S∙∙∙S and S∙∙∙N interactions has been confirmed by employing Quantum Theory of Atoms in Molecules (QTAIM). These intramolecular interactions occur among the sulfur and nitrogen atoms of the levamisole ligands and also the nitrogen atoms of the thiocyanate. Direct current (dc) magnetic analyses reveal presence of zero field splitting (ZFS) and large magnetic anisotropy on Co(II). Detailed ab initio ligand field theory calculations quantitatively predicted the magnitude of ZFS. Prominent field‐induced single‐ion magnet (SIM) behavior was observed for 1 from dynamic magnetization measurements. Slow magnetic relaxation follows an Orbach mechanism with the effective energy barrier Ueff = 29.6 (7) K and relaxation time to = 1.4 (4) × 10−9 s.

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Slow magnetization relaxation in a tetrahedrally coordinated mononuclear Co(ii) complex exclusively ligated with phenanthroline ligands

Abstract: Clear frequency-dependent out-of-phase signals as well as a series of careful experiments indicate that the purely nitrogen coordinated mononuclear Co(ii) complex reported here is a SIM.

Cited by 5 publications

References 61 publications

Cobalt(II) Single-Ion Magnet Coordinated by Double Deprotonation of 2,2′-Bipyridine-6,6′-diol Ligands

Cobalt(II) Single-Ion Magnet Coordinated by Double Deprotonation of 2,2′-Bipyridine-6,6′-diol Ligands

Phonon-induced relaxation mechanisms are changed by a chelating effect in a Co^II single-ion magnet

Levamisole Based Co(II) Single‐Ion Magnet

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Slow magnetization relaxation in a tetrahedrally coordinated mononuclear Co(ii) complex exclusively ligated with phenanthroline ligands

Abstract: Clear frequency-dependent out-of-phase signals as well as a series of careful experiments indicate that the purely nitrogen coordinated mononuclear Co(ii) complex reported here is a SIM.

Cited by 5 publications

References 61 publications

Cobalt(II) Single-Ion Magnet Coordinated by Double Deprotonation of 2,2′-Bipyridine-6,6′-diol Ligands

Cobalt(II) Single-Ion Magnet Coordinated by Double Deprotonation of 2,2′-Bipyridine-6,6′-diol Ligands

Phonon-induced relaxation mechanisms are changed by a chelating effect in a CoII single-ion magnet

Levamisole Based Co(II) Single‐Ion Magnet

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Phonon-induced relaxation mechanisms are changed by a chelating effect in a Co^II single-ion magnet