Slow Magnetic Relaxations in Cobalt(II) Tetranitrate Complexes. Studies of Magnetic Anisotropy by Inelastic Neutron Scattering and High-Frequency and High-Field EPR Spectroscopy

Lei Chen; Hui Hui Cui; Shelby E. Stavretis; Seth C. Hunter; Yi Quan Zhang; Xue Tai Chen; Yi Chen Sun; Zhenxing Wang; You Song; Andrey A. Podlesnyak; Zhong Wen Ouyang; Zi Ling Xue

doi:10.1021/acs.inorgchem.6b01544

Slow Magnetic Relaxations in Cobalt(II) Tetranitrate Complexes. Studies of Magnetic Anisotropy by Inelastic Neutron Scattering and High-Frequency and High-Field EPR Spectroscopy

Lei Chen, Hui Hui Cui, Shelby E. Stavretis, Seth C. Hunter, Yi Quan Zhang, Xue Tai Chen, Yi Chen Sun, Zhenxing Wang, You Song, Andrey A. Podlesnyak, Zhong Wen Ouyang, Zi Ling Xue

Direct Geometry

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Abstract

Three mononuclear cobalt(II) tetranitrate complexes (A)₂[Co(NO₃)₄] with different countercations, Ph₄P⁺ (1), MePh₃P⁺ (2), and Ph₄As⁺ (3), have been synthesized and studied by X-ray single-crystal diffraction, magnetic measurements, inelastic neutron scattering (INS), high-frequency and high-field EPR (HF-EPR) spectroscopy, and theoretical calculations. The X-ray diffraction studies reveal that the structure of the tetranitrate cobalt anion varies with the countercation. 1 and 2 exhibit highly irregular seven-coordinate geometries, while the central Co(II) ion of 3 is in a distorted-dodecahedral configuration. The sole magnetic transition observed in the INS spectroscopy of 1-3 corresponds to the zero-field splitting (2(D² + 3E²)^1/2) from 22.5(2) cm^-1 in 1 to 26.6(3) cm^-1 in 2 and 11.1(5) cm^-1 in 3. The positive sign of the D value, and hence the easy-plane magnetic anisotropy, was demonstrated for 1 by INS studies under magnetic fields and HF-EPR spectroscopy. The combined analyses of INS and HF-EPR data yield the D values as +10.90(3), +12.74(3), and +4.50(3) cm^-1 for 1-3, respectively. Frequency- and temperature-dependent alternating-current magnetic susceptibility measurements reveal the slow magnetization relaxation in 1 and 2 at an applied dc field of 600 Oe, which is a characteristic of field-induced single-molecule magnets (SMMs). The electronic structures and the origin of magnetic anisotropy of 1-3 were revealed by calculations at the CASPT2/NEVPT2 level.

Original language	English
Pages (from-to)	12603-12617
Number of pages	15
Journal	Inorganic Chemistry
Volume	55
Issue number	24
DOIs	https://doi.org/10.1021/acs.inorgchem.6b01544
State	Published - Dec 19 2016

Funding

We are grateful for financial support from the National Basic Research Program of China (No. 2013CB922102 to X.-T.C. and Y.S.), the Natural Science Grant of China (No. 21471078 to X.-T.C.), the Natural Science Foundation of Jiangsu Province of China (BK20151542), and the U.S. National Science Foundation (CHE-1362548 and CHE-1633870 to Z.-L.X.). Acknowledgment is also made to the donors of the American Chemical Society Petroleum Research Fund for partial support of this research.

Funders	Funder number
Natural Science Grant of China	21471078
U.S. National Science Foundation	CHE-1633870, CHE-1362548
National Science Foundation	1633870, 1362548
American Chemical Society Petroleum Research Fund
Natural Science Foundation of Jiangsu Province	BK20151542
National Basic Research Program of China (973 Program)	2013CB922102

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10.1021/acs.inorgchem.6b01544

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Chen, L., Cui, H. H., Stavretis, S. E., Hunter, S. C., Zhang, Y. Q., Chen, X. T., Sun, Y. C., Wang, Z., Song, Y., Podlesnyak, A. A., Ouyang, Z. W., & Xue, Z. L. (2016). Slow Magnetic Relaxations in Cobalt(II) Tetranitrate Complexes. Studies of Magnetic Anisotropy by Inelastic Neutron Scattering and High-Frequency and High-Field EPR Spectroscopy. Inorganic Chemistry, 55(24), 12603-12617. https://doi.org/10.1021/acs.inorgchem.6b01544

@article{2fe939b300304863a1fb0d037947132a,

title = "Slow Magnetic Relaxations in Cobalt(II) Tetranitrate Complexes. Studies of Magnetic Anisotropy by Inelastic Neutron Scattering and High-Frequency and High-Field EPR Spectroscopy",

abstract = "Three mononuclear cobalt(II) tetranitrate complexes (A)2[Co(NO3)4] with different countercations, Ph4P+ (1), MePh3P+ (2), and Ph4As+ (3), have been synthesized and studied by X-ray single-crystal diffraction, magnetic measurements, inelastic neutron scattering (INS), high-frequency and high-field EPR (HF-EPR) spectroscopy, and theoretical calculations. The X-ray diffraction studies reveal that the structure of the tetranitrate cobalt anion varies with the countercation. 1 and 2 exhibit highly irregular seven-coordinate geometries, while the central Co(II) ion of 3 is in a distorted-dodecahedral configuration. The sole magnetic transition observed in the INS spectroscopy of 1-3 corresponds to the zero-field splitting (2(D2 + 3E2)1/2) from 22.5(2) cm-1 in 1 to 26.6(3) cm-1 in 2 and 11.1(5) cm-1 in 3. The positive sign of the D value, and hence the easy-plane magnetic anisotropy, was demonstrated for 1 by INS studies under magnetic fields and HF-EPR spectroscopy. The combined analyses of INS and HF-EPR data yield the D values as +10.90(3), +12.74(3), and +4.50(3) cm-1 for 1-3, respectively. Frequency- and temperature-dependent alternating-current magnetic susceptibility measurements reveal the slow magnetization relaxation in 1 and 2 at an applied dc field of 600 Oe, which is a characteristic of field-induced single-molecule magnets (SMMs). The electronic structures and the origin of magnetic anisotropy of 1-3 were revealed by calculations at the CASPT2/NEVPT2 level.",

author = "Lei Chen and Cui, {Hui Hui} and Stavretis, {Shelby E.} and Hunter, {Seth C.} and Zhang, {Yi Quan} and Chen, {Xue Tai} and Sun, {Yi Chen} and Zhenxing Wang and You Song and Podlesnyak, {Andrey A.} and Ouyang, {Zhong Wen} and Xue, {Zi Ling}",

note = "Publisher Copyright: {\textcopyright} 2016 American Chemical Society.",

year = "2016",

month = dec,

day = "19",

doi = "10.1021/acs.inorgchem.6b01544",

language = "English",

volume = "55",

pages = "12603--12617",

journal = "Inorganic Chemistry",

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publisher = "American Chemical Society",

number = "24",

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Chen, L, Cui, HH, Stavretis, SE, Hunter, SC, Zhang, YQ, Chen, XT, Sun, YC, Wang, Z, Song, Y, Podlesnyak, AA, Ouyang, ZW & Xue, ZL 2016, 'Slow Magnetic Relaxations in Cobalt(II) Tetranitrate Complexes. Studies of Magnetic Anisotropy by Inelastic Neutron Scattering and High-Frequency and High-Field EPR Spectroscopy', Inorganic Chemistry, vol. 55, no. 24, pp. 12603-12617. https://doi.org/10.1021/acs.inorgchem.6b01544

Slow Magnetic Relaxations in Cobalt(II) Tetranitrate Complexes. Studies of Magnetic Anisotropy by Inelastic Neutron Scattering and High-Frequency and High-Field EPR Spectroscopy. / Chen, Lei; Cui, Hui Hui; Stavretis, Shelby E. et al.
In: Inorganic Chemistry, Vol. 55, No. 24, 19.12.2016, p. 12603-12617.

Research output: Contribution to journal › Article › peer-review

TY - JOUR

T1 - Slow Magnetic Relaxations in Cobalt(II) Tetranitrate Complexes. Studies of Magnetic Anisotropy by Inelastic Neutron Scattering and High-Frequency and High-Field EPR Spectroscopy

AU - Chen, Lei

AU - Cui, Hui Hui

AU - Stavretis, Shelby E.

AU - Hunter, Seth C.

AU - Zhang, Yi Quan

AU - Chen, Xue Tai

AU - Sun, Yi Chen

AU - Wang, Zhenxing

AU - Song, You

AU - Podlesnyak, Andrey A.

AU - Ouyang, Zhong Wen

AU - Xue, Zi Ling

PY - 2016/12/19

Y1 - 2016/12/19

N2 - Three mononuclear cobalt(II) tetranitrate complexes (A)2[Co(NO3)4] with different countercations, Ph4P+ (1), MePh3P+ (2), and Ph4As+ (3), have been synthesized and studied by X-ray single-crystal diffraction, magnetic measurements, inelastic neutron scattering (INS), high-frequency and high-field EPR (HF-EPR) spectroscopy, and theoretical calculations. The X-ray diffraction studies reveal that the structure of the tetranitrate cobalt anion varies with the countercation. 1 and 2 exhibit highly irregular seven-coordinate geometries, while the central Co(II) ion of 3 is in a distorted-dodecahedral configuration. The sole magnetic transition observed in the INS spectroscopy of 1-3 corresponds to the zero-field splitting (2(D2 + 3E2)1/2) from 22.5(2) cm-1 in 1 to 26.6(3) cm-1 in 2 and 11.1(5) cm-1 in 3. The positive sign of the D value, and hence the easy-plane magnetic anisotropy, was demonstrated for 1 by INS studies under magnetic fields and HF-EPR spectroscopy. The combined analyses of INS and HF-EPR data yield the D values as +10.90(3), +12.74(3), and +4.50(3) cm-1 for 1-3, respectively. Frequency- and temperature-dependent alternating-current magnetic susceptibility measurements reveal the slow magnetization relaxation in 1 and 2 at an applied dc field of 600 Oe, which is a characteristic of field-induced single-molecule magnets (SMMs). The electronic structures and the origin of magnetic anisotropy of 1-3 were revealed by calculations at the CASPT2/NEVPT2 level.

AB - Three mononuclear cobalt(II) tetranitrate complexes (A)2[Co(NO3)4] with different countercations, Ph4P+ (1), MePh3P+ (2), and Ph4As+ (3), have been synthesized and studied by X-ray single-crystal diffraction, magnetic measurements, inelastic neutron scattering (INS), high-frequency and high-field EPR (HF-EPR) spectroscopy, and theoretical calculations. The X-ray diffraction studies reveal that the structure of the tetranitrate cobalt anion varies with the countercation. 1 and 2 exhibit highly irregular seven-coordinate geometries, while the central Co(II) ion of 3 is in a distorted-dodecahedral configuration. The sole magnetic transition observed in the INS spectroscopy of 1-3 corresponds to the zero-field splitting (2(D2 + 3E2)1/2) from 22.5(2) cm-1 in 1 to 26.6(3) cm-1 in 2 and 11.1(5) cm-1 in 3. The positive sign of the D value, and hence the easy-plane magnetic anisotropy, was demonstrated for 1 by INS studies under magnetic fields and HF-EPR spectroscopy. The combined analyses of INS and HF-EPR data yield the D values as +10.90(3), +12.74(3), and +4.50(3) cm-1 for 1-3, respectively. Frequency- and temperature-dependent alternating-current magnetic susceptibility measurements reveal the slow magnetization relaxation in 1 and 2 at an applied dc field of 600 Oe, which is a characteristic of field-induced single-molecule magnets (SMMs). The electronic structures and the origin of magnetic anisotropy of 1-3 were revealed by calculations at the CASPT2/NEVPT2 level.

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U2 - 10.1021/acs.inorgchem.6b01544

DO - 10.1021/acs.inorgchem.6b01544

M3 - Article

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SN - 0020-1669

VL - 55

SP - 12603

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JO - Inorganic Chemistry

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ER -

Slow Magnetic Relaxations in Cobalt(II) Tetranitrate Complexes. Studies of Magnetic Anisotropy by Inelastic Neutron Scattering and High-Frequency and High-Field EPR Spectroscopy

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