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Bhatt G, Sharma T, Gupta SK, Meyer F, Rajaraman G, Murugavel R. Tuning Magnetic Anisotropy in Co(II) Tetrahedral Carbazole-Modified Phosphine Oxide Single-Ion Magnets: Importance of Structural Distortion versus Heavy-Ion Effect. Inorg Chem 2023; 62:18915-18925. [PMID: 37947449 DOI: 10.1021/acs.inorgchem.3c02401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2023]
Abstract
Three mononuclear cobalt(II) tetrahedral complexes [Co(CzPh2PO)2X2] (CzPh2PO = (9H-carbazol-9-yl)diphenylphosphine oxide and X = Cl (1), Br (2), I (3)) have been synthesized using a simple synthetic approach to examine their single-ion magnetic (SIM) behavior. A detailed study of the variation in the dynamic magnetic properties of the Co(II) ion in a tetrahedral ligand field has been carried out by the change of the halide ligand. The axial zero-field splitting parameter D was found to vary from -16.4 cm-1 in 1 to -13.8 cm-1 in 2 and +14.6 cm-1 in 3. All the new complexes exhibit field-induced SIM behavior. The results obtained from ab initio CASSF calculations match well with the experimental data, revealing how halide ions induce a change in the D value as we move from Cl- to I-. The ab initio calculations further reveal that the change in the sign of D is due to the multideterminant characteristics of the ground state wave function of 1 and 2, while single-determinant characteristics are instead observed for 3. To gain a better understanding of the relationship between the structural distortion and the sign and magnitude of D values, magnetostructural D correlations were developed using angular relationships, revealing the importance of structural distortions over the heavy halide effect in controlling the sign of D values. This study broadens the scope of employing electronically and sterically modified phosphine oxide ligands in building new types of air-stable Co(II) SIMs.
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Affiliation(s)
- Gargi Bhatt
- Department of Chemistry, Indian Institute of Technology Bombay, Powai 400076, Mumbai, India
| | - Tanu Sharma
- Department of Chemistry, Indian Institute of Technology Bombay, Powai 400076, Mumbai, India
| | - Sandeep K Gupta
- University of Göttingen, Institute of Inorganic Chemistry, Göttingen D-37077, Germany
| | - Franc Meyer
- University of Göttingen, Institute of Inorganic Chemistry, Göttingen D-37077, Germany
| | - Gopalan Rajaraman
- Department of Chemistry, Indian Institute of Technology Bombay, Powai 400076, Mumbai, India
| | - Ramaswamy Murugavel
- Department of Chemistry, Indian Institute of Technology Bombay, Powai 400076, Mumbai, India
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Yureva EA, Korchagin DV, Anichkin AA, Shilov GV, Babeshkin KA, Efimov NN, Palii AV, Aldoshin SM. Evidence for zero-field slow magnetic relaxation in a Co(II) complex with a pseudo-tetrahedral N 2I 2 environment. Dalton Trans 2022; 51:11916-11921. [PMID: 35876183 DOI: 10.1039/d2dt01336c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Herein, we report on the synthesis, structure and magnetic properties of a four-coordinate mononuclear Co(II) diiodide complex with the 3,5-dimethylpyrazole ligand. A distorted tetrahedral local coordination environment around the central cobalt ion is formed by the two nitrogen atoms of two monodentate pyrazole ligands and by iodide ions. Direct current (dc) magnetic measurements in combination with ab initio SA-CASSCF/NEVPT2 quantum-chemical calculations revealed a strong easy-axis-type magnetic anisotropy with a record value Dexp = -30.58(3) cm-1 of the axial zero field splitting parameter for pseudo-tetrahedral Co(II)-based CoL2Hal2 complexes. Moreover, it is the only complex in this series demonstrating the slow relaxation of magnetization at zero dc field. The Orbach process is shown to be the dominant mechanism of magnetic relaxations in the high temperature range, while the quantum tunneling of magnetization produces the leading contribution to the overall relaxation at temperatures below 4 K.
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Affiliation(s)
- E A Yureva
- Institute of Problems of Chemical Physics, Russian Academy of Sciences, 1, Acad. Semenov prosp., 142432 Chernogolovka, Moscow Region, Russia.
| | - D V Korchagin
- Institute of Problems of Chemical Physics, Russian Academy of Sciences, 1, Acad. Semenov prosp., 142432 Chernogolovka, Moscow Region, Russia.
| | - A A Anichkin
- Institute of Problems of Chemical Physics, Russian Academy of Sciences, 1, Acad. Semenov prosp., 142432 Chernogolovka, Moscow Region, Russia. .,Faculty of Fundamental Physical and Chemical Engineering, Moscow State University, 1-3, Leninskiye Gory, 119991 Moscow, Russia
| | - G V Shilov
- Institute of Problems of Chemical Physics, Russian Academy of Sciences, 1, Acad. Semenov prosp., 142432 Chernogolovka, Moscow Region, Russia.
| | - K A Babeshkin
- N. S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, 31, Leninsky prosp., 119991 Moscow, Russia
| | - N N Efimov
- N. S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, 31, Leninsky prosp., 119991 Moscow, Russia
| | - A V Palii
- Institute of Problems of Chemical Physics, Russian Academy of Sciences, 1, Acad. Semenov prosp., 142432 Chernogolovka, Moscow Region, Russia.
| | - S M Aldoshin
- Institute of Problems of Chemical Physics, Russian Academy of Sciences, 1, Acad. Semenov prosp., 142432 Chernogolovka, Moscow Region, Russia.
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