Single-ion Magnets Research Articles

The Impact of Coordination Distortion on Magnetic Properties of Co (II) Single‐Ion Magnets With Trigonal Prism Coordination Geometry

ABSTRACTTwo Co (II) compounds [Co (abs)2]·2H2O (1) and [Co (pabs)2] (2) (Habs = N‐(pyridine‐2′‐yl methylene)‐2‐aminobenzene sulfonic acid, Hpabs = N‐[(pyridine‐2′‐yl)(phenyl)methylene]‐2‐aminobenzene sulfonic acid) were synthesized by the introduction of sulfonate ligands with different substitutions. Both Co (II) ions are located in a trigonal prism coordination environment with different coordination distortions. Static magnetic studies and theoretical calculations found that easy‐axis magnetic anisotropy is present in both complexes. The contributions of the negative D values are principally derived from the first quartet excited state. Dynamic magnetic investigations uncovered that both compounds have field‐induced single‐ion magnet (SIM) behavior and their magnetic relaxations mainly realize through Raman and direct pathways.

Effect of Substituents in Equatorial Hexaazamacrocyclic Schiff Base Ligands on the Construction and Magnetism of Pseudo D6h Single-Ion Magnets.

Three mononuclear DyIII compounds [DyL1(Ph3SiO)2][BPh4]·MeCN·2H2O (1), [DyL2(Ph3SiO)2][BPh4]·C2H5OH·H2O (2), and [DyL3(Ph3SiO)(OAc)][BPh4]·CH3OH·3H2O (3) and their corresponding YIII diluted analogues [Dy0.0967Y0.9033L1(Ph3SiO)2][BPh4]·MeCN·2H2O (1@Y), [Dy0.2668Y0.7332L2(Ph3SiO)2][BPh4]·C2H5OH·H2O (2@Y), and [Dy0.1260Y0.8740L3(Ph3SiO)(OAc)][BPh4]·CH3OH·3H2O (3@Y) were synthesized with hexaazamacrocyclic Schiff base ligands as an equatorial ligand. The substituents in the equatorial hexaazamacrocyclic Schiff base ligand show a significant effect on the replacement of the axial ligands. Compounds 1, 2, and 3 are typical zero dc field single-molecule magnets with effective energy barriers (Ueff) of 1092(6), 946.1(7), and 150.1(9) K, respectively. Although the effective energy barriers of 1 and 2 are close, the magnetic hysteresis remains open up to 20 K for 1, twice as large as that of 2 (10 K), which is different from the previously reported compounds, probably due to nonplanarity N6 in the equator. Ab initio calculations indicate that the ground states of compounds 1 and 2 exhibit high anisotropy and pure second and third excited states, while compound 3 exhibits pure ground-state anisotropy and highly mixed excited states, leading to the easy occurrence of quantum tunneling of magnetization between the ground and excited states in compound 3. This work indicates that the substituents in equatorial hexaazamacrocyclic Schiff base ligands have a significant effect on the construction and magnetic properties of DyIII SIMs with D6h symmetry.

THz-EPR-based Magneto-Structural Correlations for Cobalt(II) Single-Ion Magnets With Bis-Chelate Coordination.

New cobalt(II)-based complexes with [N2O2] coordination formed by two bis-chelate ligands were synthesized and characterized by a multi-technique approach. The complexes possess an easy-axis anisotropy (D<0) and magnetic measurements show a field-induced slow relaxation of magnetization. The spin-reversal barriers, i. e., the splitting of the two lowest Kramers doublets (UZFS), have been measured by THz-EPR spectroscopy, which allows to distinguish the two crystallographically independent species present in one of the complexes. Based on these experimental UZFS energies together with those for related complexes reported in literature, it was possible to establish magneto-structural correlations. UZFS linearly depends on the elongation parameter ϵT of the (pseudo-)tetrahedral coordination, which is given by the ratio between the average obtuse and acute angles at the cobalt(II) ion, while UZFS was found to be virtually independent of the twist angle of the chelate planes. With increasing deviation from the orthogonality of the latter, the rhombicity (|E/D|) increases.

First TPymT-Ln complexes (TPymT = 2,4,6-Tris(2-pyrimidyl)-1,3,5-triazine; Ln = Eu, Gd, Tb, Dy): Solvothermal synthesis, structure, magnetic and photoluminescent properties

Four novel mononuclear lanthanide complexes, [Ln(TPymT)(NO3)3(H2O)2] (Ln: Eu3+ (1), Gd3+ (2), Tb3+ (3) and Dy3+ (4)), have been solvothermally synthesized using multidentate 2,4,6-tris(2-pyrimidyl)-1,3,5-triazine (TPymT). Compounds 1–3 have been characterized by means of elemental analysis, FT-IR, and single-crystal/powder X-ray diffraction analysis. Compound 4 was structurally characterized. The Ln3+ ion in 1–4 is ten-coordinated, where TPymT serves as an N3 donor in an isostructural series. The alternating-current magnetic studies showed frequency dependence below ca. 10 K for 3, as an indication of a single-ion magnet. The activation energy for the magnetization reorientation was estimated as Ueff/kB = 95(9) K after applying a dc bias field 2000 Oe for 3. The photoluminescent studies clarified that 1 and 3 behaved as red and green light emitters with quantum yields as high as 17 and 39 %, respectively. The TD-DFT calculation supports the energy level scheme of ground and excited states of TPymT together with the reference compound 4′-phenyl-2,2’:6′,2″-terpyridine. The present work suggests a broad chance and motivation to apply TPymT to the field of 4f coordination chemistry.

Metalo Hydrogen-Bonded Organic Frameworks Constructed by Coordinated Chains for Magnetic and Proton-Conductive Bifunctionality.

Metalo hydrogen-bonded organic frameworks (MHOFs) have received growing interest in designing crystalline functional materials. However, reports on bifunctional MHOFs showing magnetic and proton-conductive properties are extremely limited and their design is challenging. Herein, we investigated the magnetic and proton-conductive properties of two sulfonated CoHOF and MnHOF, {M(H2O)2(abs)2}n (M = Co2+ and Mn2+, Habs = 4-aminoazobenzene-4'-sulfonic anion), constructed by coordination chains. The supramolecular frameworks sustained by H bonds between -SO3- and coordinated water show directional ladder-type H bonds with hydrophilic nanochannels, leading to high proton conduction with exceptionally high conductivity around 10-2 S cm-1 at 100 °C under 97% relative humidity. In particular, the maximum σ value of CoHOF, 2.11 × 10-2 S cm-1, recorded the highest value among the reported proton-conducting materials showing slow magnetic relaxation. Meanwhile, the molecular structure of organosulfonate enables the magnetic isolation of high-spin Co2+ and Mn2+ centers in the frameworks. Magnetic measurements indicated that the MHOFs show field-induced single-ion magnet (SIM) properties, making these compounds rare magnetic-proton-conductive MHOFs. The work provides not only two unique MHOFs with SIM behavior and high proton conduction performance but also avenues for designing stable bifunctional MHOFs via a coordination chain approach.

Integrating Polyoxometalate into Dy(III)-based Single-molecule Magnets with Pentagonal Bipyramidal Symmetry.

Polyoxometalates (POMs) with various coordination fashions are versatile ligands for constructing single-ion magnets (SIMs), but enforcing POM-SIMs with a specific geometry remains a synthetic challenge. Herein, we synthesized a POM-cocrystallized DyIII-SIM [Dy(OPPh3)4(H2O)3][PW12O40]·4EtOH (1Dy) and a POM-ligated DyIII-SIM [{Dy(OPPh3)3(H2O)3}{PW12O40}]·Ph3PO·H2O (2Dy) with pentagonal bipyramidal local coordination geometry. Magnetic measurements indicate that 1Dy displays field-induced single-molecule magnet (SMM) behavior and the relaxation is dominated by under-barrier processes. 2Dy exhibits spin-lattice relaxation at a broader temperature region with a reversal barrier over 300 K. Magneto-structural analysis reveals that the enhancement of SMM behavior originated from the equatorial replacement of Ph3PO by POM, which strengthens the axial anisotropy in 2Dy. Luminescent experiments indicate that the characteristic DyIII emissions of 1Dy are covered up by the strong π-π* emission of Ph3PO at low-temperature regions. As for 2Dy, partial DyIII emission persists thanks to the antenna effect between DyIII and POM.

Modulating Magnetic Performance in DyIII Single Ion Magnets With N5O2 Ligands

ABSTRACT[Dy (LMe)(H2O)]CF3SO3·0.25H2O (1·0.25H2O), where H2LMe is the reported ligand 2,2′‐(((pyridine‐2,6‐diylbis (methylene))bis((pyridin‐2‐ylmethyl)azanediyl))bis (methylene))bis(4‐methylphenol), shows the DyIII ion in an N5O3 environment, with triangular dodecahedral geometry (D2d symmetry). 1·0.25H2O is a single ion magnet (SIM) with an energy barrier for spin reversal of 510 K, and open hysteresis loops up to 8 K. The magnetostructural comparison of 1·0.25H2O with some closely related complexes and with other eight‐coordinated SIMs with high energy barriers (&gt; 300 K) allows to draw some conclusions to enhance the magnetic performance in these nanomagnets with non‐purely axial geometries. Ab initio calculations complement and support the experimental results.

Salt of dysprosium(iii) tetrakis(hexafluoroacetylacetonate) with 1,1′-dimethyl-4,4′-bipyridinium as a new single-ion magnet

Salt of dysprosium(iii) tetrakis(hexafluoroacetylacetonate) with 1,1′-dimethyl-4,4′-bipyridinium as a new single-ion magnet

Levamisole Based Co(II) Single-Ion Magnet.

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 τo=1.4 (4)×10-9 s.

Single-Ion Magnetism of the [DyIII(hfac)4]- Anions in the Crystalline Semiconductor {TSeT1.5}●+[DyIII(hfac)4]- Containing Weakly Dimerized Stacks of Tetraselenatetracene.

The oxidation of tetraselenatetracene (TSeT) by tetracyanoquinodimethane in the presence of dysprosium(III) tris(hexafluoroacetylacetonate), DyIII(hfac)3, produces black crystals of {TSeT1.5}●+[DyIII(hfac)4]- (1) salt, which combines conducting and magnetic sublattices. It contains one-dimensional stacks composed of partially oxidized TSeT molecules (formal averaged charge is +2/3). Dimers and monomers can be outlined within these stacks with charge and spin density redistribution. The spin triplet state of the dimers is populated above 128 K with an estimated singlet-triplet energy gap of 542 K, whereas spins localized on the monomers show paramagnetic behavior. A semiconducting behavior is observed for 1 with the activation energy of 91 meV (measured by the four-probe technique for an oriented single crystal). The DyIII ions coordinate four hfac- anions in [DyIII(hfac)4]-, providing D2d symmetry. Slow magnetic relaxation is observed for DyIII under an applied static magnetic field of 1000 Oe, and 1 is a single-ion magnet (SIM) with spin reversal barrier Ueff = 40.2 K and magnetic hysteresis at 2 K. Contributions from DyIII and TSeT●+ paramagnetic species are seen in EPR. The DyIII ion rarely manifests EPR signals, but such signal is observed in 1. It appears due to narrowing below 30 K and has g4 = 6.1871 and g5 = 2.1778 at 5.4 K.

Crystal structure and cryomagnetic study of a mononuclear erbium(III) oxamate inclusion complex.

The synthesis, crystal structure and magnetic properties of an oxamate-containing erbium(III) complex, namely, tetrabutylammonium aqua[N-(2,4,6-trimethylphenyl)oxamato]erbium(III)-dimethyl sulfoxide-water (1/3/1.5), (C16H36N)[Er(C11H12NO3)4(H2O)]·3C2H6OS·1.5H2O or n-Bu4N[Er(Htmpa)4(H2O)]·3DMSO·1.5H2O (1), are reported. The crystal structure of 1 reveals the occurrence of an erbium(III) ion, which is surrounded by four N-phenyl-substituted oxamate ligands and one water molecule in a nine-coordinated environment, together with one tetrabutylammonium cation acting as a counter-ion, and one water and three dimethyl sulfoxide (DMSO) molecules of crystallization. Variable-temperature static (dc) and dynamic (ac) magnetic measurements were carried out for this mononuclear complex, revealing that it behaves as a field-induced single-ion magnet (SIM) below 5.0 K.

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

In this study, we synthesized a new Co(II) complex, [NMe4]2[Co(bpyO2)2] (1), using deprotonated 2,2'-bipyridine-6,6'-diol ligands (bpyO2 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-of-phase 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 pyridine-coordinated 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.

The paradigm of magnetic molecule in quantum matter: Slow molecular spin relaxation

The quantum nature of single-ion magnets, single-molecule magnets, and single-chain magnets has been manifested among other phenomena by magnetic hysteresis due to slow spin relaxation, competing with fast quantum tunneling at low temperatures. Slow spin relaxation, described by Arrhenius-type law with the effective barrier energies Ueff = 50 cm–1, was discovered 3 decades ago in paramagnetic Mn12-acetate complex of oxy-bridged mixed-valence manganese ions, below the blocking temperature TB = 3 K. In contrast to common magnetic materials, it is governed primarily by magnetic anisotropy, set by zero-splitting of spin states of a magnetic ion in a field of ligands, and spin-lattice coupling. The emerging studies on the border of coordination chemistry, physics of spin systems with reduced dimensionality, and nanotechnologies, were performed in search of routes for enhancement of Ueff and TB characteristics, in line with increase of operation temperature and quantum correlation time, mandatory for quantum applications. The best results with TB ∼ 80 K and Ueff ∼ 1261 cm–1, were obtained for DyIII single-ion magnet, so far. Numerous excellent research and review articles address particular activities behind this achievement. It follows, that present challenges are dictated by the rational development of novel, smart magnetic molecules, featured by butterfly cores, cyano-bridges, 2D metal-organic frameworks, and metal-free graphene nanoclusters, as well as stable free radicals, magnetized by spare electrons. These species are briefly considered here with respect to the unique experience of international collaborative activity, established by Prof. Juan Bartolomé.

Magnetic Anisotropy and Relaxation in Four-Coordinate Cobalt(II) Single-Ion Magnets with a [CoIIO4] Core.

A mononuclear four-coordinate Co(II) complex with a [CoIIO4] core, namely, PPN[Li(MeOH)4][Co(L)2] (1) (PPN = bis(phosphoranediyl)iminium; H2L = perfluoropinacol), has been studied by X-ray crystallography, magnetic characterization, and theoretical calculations. This complex presents a severely distorted coordination geometry. The O-Co-O bite angle is 83.42°/83.65°, and the dihedral twist angle between the O-Co-O chelate planes is 55.6°. The structural distortion results in a large easy-axis magnetic anisotropy with D = -104(1) cm-1 and a transverse component with |E| = +4(2) cm-1. Alternating current (ac) susceptibility measurements demonstrate that 1 exhibits slow relaxation of magnetization at zero static field. However, the frequency-dependent out-of-phase (χ"M) susceptibilities of 1 at 0 Oe do not show a characteristic maximum. Upon the application of a dc field or the dilution with a diamagnetic Zn matrix, the quantum tunneling of magnetization (QTM) process can be successfully suppressed. Notably, after dilution with the Zn matrix, the obtained sample exhibits a structure different from that of the pristine complex. In this altered sample, the asymmetric unit does not contain the Li(MeOH)4+ cation, resulting in an O-Co-O bite angle of 86.05° and a dihedral twist angle of 75.84°, thereby leading to an approximate D2d symmetry. Although such differences are not desirable for magnetic studies, this study still gives some insights. Theoretical calculations reveal that the D parameter is governed by the O-Co-O bite angle, in line with our previous report for other tetrahedral Co(II) complex with a [CoIIN4] core. On the other hand, the rhombic component is found to increase as the dihedral angle deviates from 90°. These findings provide valuable guidelines for fine-tuning the magnetic properties of Co(II) complexes.

Orientation‐Driven Large Magnetic Hysteresis of Er(III) Cyclooctatetraenide‐Based Single‐Ion Magnets Adsorbed on Ag(100)

The molecular self‐assembly and the magnetic properties of two cyclooctatetraenide (COT)‐based single‐ion magnets (SIM) adsorbed on Ag(100) in the sub‐monolayer (ML) range are reported. Our study combines scanning‐tunneling microscopy, X‐ray photoemission spectroscopy and polarized X‐ray absorption spectroscopy to show that Cp*ErCOT (Cp* = 1,2,3,4,5‐pentamethylcyclopentadienide anion) SIMs self‐assemble as alternating compact parallel rows including standing‐up and lying‐down conformations, following the main crystallographic directions of the substrate. Conversely, K[Er(COT)2], obtained from subliming the [K(18‐c‐6)][Er(COT)2]·2THF salt, forms uniaxially ordered domains with the (COT)2− rings perpendicular to the substrate plane. The polarization‐dependent X‐ray absorption spectra reproduced by the multiX simulations suggest that the strong in‐plane magnetic anisotropy of K[Er(COT)2]/Ag(100) and the weak out‐of‐plane anisotropy of Cp*ErCOT/Ag(100) can be attributed to the strikingly different surface ordering of these two complexes. Compared to the bulk phase, surface‐supported K[Er(COT)2] exhibits a similarly large hysteresis opening, while the Cp*ErCOT shows a rather small opening. This result reveals that despite structural similarities, the two organometallic SMMs have strongly different magnetic properties when adsorbed on the metal substrate, attributed to the different orientations and the resulting interactions of the ligand rings with the surface.

Three coordinated first row-transition metal complexes, [M{N(SiMe3)2}3]−1/0: Structure, bonding, and magnetic properties

Structure, bonding, and magnetic properties of [M{N(SiMe3)2}3]−1/0 (M = first row-transition metal, Sc-Cu in + 2/+3 oxidation state) complexes are studied. The atoms in molecules (AIM) analysis shows that non-covalent interactions between the methyl hydrogens are prevalent. Energy decomposition analysis coupled with natural orbital for chemical valence (EDA-NOCV) analysis shows that the ligand is bonded to the metal ions through σ and π bonding. In addition, the reasonable contribution from the dispersion interaction supports van der Waals' type of interaction. The highest value of magnetic anisotropy (D) is calculated in the NiII complex with a value of −382.945 (−234.145) cm−1 at the CASSCF (NEVPT2) level of theory. It is significantly higher than the previously reported values of −14.644 (−15.631) and −63.691 (−64.000) cm−1 in similar CrII and MnIII complexes, respectively. Ab Initio Ligand Field Theory (AILFT) is utilized to calculate the splitting of the d-orbitals in all the metal complexes. In the NiII complexes, the blocking barrier (Ueff) is found to be 127 cm−1. Thus, it has a high potential to be utilized as a single ion magnet (SIM).

Slow magnetic relaxation and proton conduction in a highly hydrogen-bonded dinuclear holmium(III) complex

Multifunctional magnetic-electrical materials are highly interesting, such as proton-conductive lanthanide single-ion magnets (SIMs). Herein, we reported the synthesis, crystal structure, magnetic and electrical properties of a bifunctional binuclear holmium(III) complex, [Ho2(H2dobdc)(H2O)14]·(H2dobdc)2·8H2O (Ho2, H4dobdc = 2,5-dioxodo-1,4-benzenedicarboxylate), which was constructed by a hydroxy‑functionalizd dicarboxybenzene and holmium(III) ions. Interestingly, single-crystal X-ray diffraction analysis reveals a highly hydrogen-bonded supramolecular structure and highly oxygenated site were formed within the complex. Magnetic measurements indicate the complex exhibits filed-induced slow magnetic relaxation property. Additionally, the impedance spectroscopy measurements show the complex also exhibits humidity- and temperature-dependent proton conduction behaviour via the Grotthus mechanism. These results support a proton-conductive holmium(III) single-ion magnet of Ho2. This work not only provides the first bifunctional HoIII complexes showing slow magnetic relaxation and proton-conducting behaviour but also a supramolecular way for advanced magnetic-electrical systems linking slow magnetic relaxation with unique proton conducting behaviour exploiting a possible cooperative behaviour.

Synthesis, crystal structure and magnetic properties of two 1D coordination polymers containing Co2+ and Cu2+ ions and 1,3,5-tris(4-carboxylphenyl)benzene

Two 1D coordination polymers, {[Co(H3BTB)2(phen)](NO3)2}n (1) and {[Cu(HBTB)2(phen)] DMF}n (2), were synthesized through a slow diffusion reaction between the metal ions Co2+ or Cu2+, 1,3,5-tris(4-carboxylphenyl)benzene (H3BTB) and 1,10-phenanthroline (phen). Single-crystal X-ray diffraction revealed that both metal centers are involved in a distorted octahedral environment. As expected for a Cu2+ ion with a d9 configuration, a pronounced Jahn-Teller distortion is observed. FTIR, powder XRD, and thermogravimetric analysis were employed for the chemical characterization of the two complexes. CASSCF-NEVPT2 was used to calculate the axial magnetic anisotropy (D) for complex 1, and the results were almost perfectly consistent with the experimental measurements. The AC magnetic susceptibility measurements revealed field-induced single-ion magnet (SIM) behavior at low temperatures for 1. EPR studies of complex 2 indicated that the Cu2+ ions are essentially isolated.

Dysprosium‐Radical Based Single‐Molecule Magnet Containing a Seven Coordinate Dy(III) Ion: A System for ab initio Study

AbstractSingle–ion magnets (SIMs) possessing a Dy(III) ion have recently attracted huge scientific attention. Herein, we report on a Dy(III)‐radical single–molecule magnet containing a seven‐coordinate Dy(III) ion with an O3N3Cl donor set. The frequency–dependent slow relaxation of magnetization has been observed below 8 K. DC magnetic studies have shown the presence of weak antiferromagnetic coupling between the Kramers ion (Dy(III), J = 15/2) and the ligand‐centered radical electron (S = 1/2) which was confirmed by multifunctional CASSCF calculations.

Slow relaxation of magnetization in the Co(II)‐phosphotungstate Keggin polyoxometalate

AbstractWe are reporting the single crystal structure of the tetrabutylammonium (TBA) salt of the old Co(II) Keggin phosphotungstate anion (Co(II)POM) and a study of the magnetic behaviour of this well‐known POM. This Co(II)POM crystallizes in a cubic cell and this high symmetry obscure a precise characterization of Co(II) coordination sphere metrics due to positional disordered. We employed DFT and SA‐SOC‐CASSCF as auxiliary tools to complement DC and AC magnetic data collected. The studied complex behaves as a field‐induced single ion magnet (SIM) showing slow relaxing magnetization below 5 K under small DC applied magnetic fields. Raman relaxation mechanisms dominates with different relaxation times observed when switching from the TBA salt to the K salt of the Co(II)POM.