Combined Experimental and Theoretical Investigation of the Origin of Magnetic Anisotropy in Pentagonal Bipyramidal Isothiocyanato Co(II), Ni(II), and Fe(III) Complexes with Quaternary-Ammonium-Functionalized 2,6-Diacetylpyridine Bisacylhydrazone
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Shcherbakov, Igor N.
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Magnetic anisotropy in pentagonal bipyramidal complexes of Co(II) (1 and 2), Fe(III) (3 and 4), and Ni(II) (5) with a 2,2′-[2,6-pyridinediylbis(ethylidyne-1-hydrazinyl-2-ylidene)]bis[N,N,N-trimethyl-2-oxoethanaminium] equatorial ligand and isothiocyanato axial ligands has been investigated by magnetic susceptibility measurements, powder X-band electron paramagnetic resonance (EPR) spectroscopy, Mössbauer spectroscopy, ab initio, and ligand-field density functional theory (LFDFT) calculations. The studied complexes display three distinct types of magnetic anisotropy. Co(II) complexes (1 and 2) show an easy plane anisotropy with large and positive D values and negligible rhombicity. The Ni(II) complex (5) has uniaxial magnetic anisotropy with a negative D value. Fe(III) complexes (3 and 4) have small zero-field splitting (ZFS) parameters. Theoretical modeling is used to rationalize the magnetic anisotropy in these systems and to identify the most important excited states that are respons...ible for the zero-field splitting. These excitations are a consequence of the electronic structure of the central metal ion in ideal pentagonal bipyramidal coordination.
Keywords:Magnetic properties / Electron paramagnetic resonance spectroscopy / Quantum mechanics / Mössbauer spectroscopy / Magnetic susceptibility measurements / ab initio / Ligand Field Theory / Group theory / Magnetic anisotropy / Zero Field Splitting / LFDFT / DFT / Theoretical modeling / Symmetry / Pentagonal Bipyramidal
Source:The Journal of Physical Chemistry C, 2019, 123, 51, 31142-31155
- American Chemical Society (ACS)
- Rational design and synthesis of biologically active and coordination compounds and functional materials, relevant for (bio)nanotechnology (RS-172035)
- Interactions of natural products, their derivatives and coordination compounds with proteins and nucleic acids (RS-172055)
- Slovenian Research Agency (P1-0175)
- Slovenian Research Agency (P1-0112)
- Southern Federal University
- The peer-reviewed version: http://cer.ihtm.bg.ac.rs/handle/123456789/3269