Gadolinium‐Triradical Complex with Ground <i>S</i> = 10 State: Synthesis, Structural Characterization and Magnetic Studies

Kanetomo, Takuya; Naoi, Yuya; Enomoto, Masaya

doi:10.1002/ejic.202001113

Cited by 7 publications

(16 citation statements)

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“…According to the usual method known for lanthanide-nitroxide coordination compounds [ 13 , 14 , 15 , 16 ], combining iPr 3 BPBN and [Gd(hfac) 3 (H 2 O) 2 ] with a molar ratio 1/1 in a dichloromethane-heptane mixed solvent afforded the polycrystalline product of [{Gd(hfac) 3 (μ- iPr 3 BPBN )} 2 ] ( 1 ; Scheme 1 ). The composition was confirmed to be 1 •(CH 2 Cl 2 ) 2 by means of spectroscopic and X-ray diffraction analyses.…”

Section: Resultsmentioning

confidence: 99%

“…The N-O bond length is 1.296 (10) Å, being typical of nitroxide complexes [ 13 , 14 , 16 , 47 ]. The coordination structure is best described as an approximate square antiprism from the SHAPE analysis [ 53 ], giving the CShM value of 1.431 to the ideal SAPR-8 for both disorder positions.…”

Section: Resultsmentioning

confidence: 99%

“…Lanthanide(4f)-radical(2p) heterospin systems afford an important class of magnetic materials [ 1 , 2 , 3 , 4 , 5 , 6 ]. As a 2p spin source, nitroxide or aminoxyl radicals [ 7 ] are widely demanded, because the oxygen atom of nitroxide radicals can serve as an O-donor to metal ions [ 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 ], and 4f-2p magnetic exchange couplings are operational [ 12 , 13 , 14 , 15 , 16 ]. Exchange coupling will reduce possible quantum tunneling of magnetization in single-molecule magnets [ 5 , 17 , 18 ].…”

Section: Introductionmentioning

confidence: 99%

“…Ferromagnetic 4f-2p exchange coupling often occurs across coordination bonds, and the nature, ferro- or antiferromagnetic, and their magnitude depend on the coordination structure [ 13 , 14 , 15 , 16 ]. A gadolinium(III) ion is often selected as a first choice to investigate exchange coupling in a spin-only treatment according to conventional magnetometry.…”

Section: Introductionmentioning

confidence: 99%

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Ferromagnetic 2p-2p and 4f-2p Couplings in a Macrocycle from Two Biradicals and Two Gadolinium(III) Ions

2022

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A new ground triplet biradical 2’,4’,6’-triisopropylbiphenyl-3,5-diyl bis(tert-butyl nitroxide) (iPr3BPBN) was prepared and characterized by means of room-temperature ESR spectroscopy displaying a zero-field splitting pattern together with a half-field signal. Complex formation with gadolinium(III) 1,1,1,5,5,5-hexafluoropentane-2,4-dionate (hfac) afforded a macrocycle [{Gd(hfac)3(m-iPr3BPBN)}2]. As the X-ray crystallographic analysis clarified, the biradical serves as a bridging ligand, giving a 16-membered ring, where each nitroxide radical oxygen atom is directly bonded to a Gd3+ ion. The magnetic study revealed that the iPr3BPBN bridge behaved as a practically triplet biradical and that the Gd3+-radical magnetic coupling was weakly ferromagnetic. The exchange parameters were estimated as 2jrad-rad/kB > 300 K and 2JGd-rad/kB = 1.2 K in the H = −2J S1•S2 convention. The DFT calculation based on the atomic coordinates clarified the ground triplet nature in metal-free iPr3BPBN and the enhanced triplet character upon coordination. The calculation also suggests that ferromagnetic coupling would be favorable when the Gd-O-N-C(sp2) torsion comes around 100°. The present results are compatible with the proposed magneto-structure relationship on the nitroxide-Gd compounds.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Ferromagnetic 2p-2p and 4f-2p Couplings in a Macrocycle from Two Biradicals and Two Gadolinium(III) Ions

2022

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“…The torsion angle table is usually listed up in a crystallographic information file (.cif), and no recalculation is needed to assess ϕ. The ϕ parameter is handy, so that the plot of J vs. ϕ has also been applied to 4f-2p heterospin systems; for example, the Gd- [183][184][185][186][187][188][189][190][191][192], Tb- [193,194], and Dy-nitroxide compounds [195,196].…”

Section: Discussionmentioning

confidence: 99%

Molecular S = 2 High-Spin, S = 0 Low-Spin and S = 0 ⇄ 2 Spin-Transition/-Crossover Nickel(II)-Bis(nitroxide) Coordination Compounds

et al. 2021

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Heterospin systems have a great advantage in frontier orbital engineering since they utilize a wide diversity of paramagnetic chromophores and almost infinite combinations and mutual geometries. Strong exchange couplings are expected in 3d–2p heterospin compounds, where the nitroxide (aminoxyl) oxygen atom has a direct coordination bond with a nickel(II) ion. Complex formation of nickel(II) salts and tert-butyl 2-pyridyl nitroxides afforded a discrete 2p–3d–2p triad. Ferromagnetic coupling is favored when the magnetic orbitals, nickel(II) dσ and radical π*, are arranged in a strictly orthogonal fashion, namely, a planar coordination structure is characterized. In contrast, a severe twist around the coordination bond gives an orbital overlap, resulting in antiferromagnetic coupling. Non-chelatable nitroxide ligands are available for highly twisted and practically diamagnetic complexes. Here, the Ni–O–N–Csp2 torsion (dihedral) angle is supposed to be a useful metric to describe the nickel ion dislocated out of the radical π* nodal plane. Spin-transition complexes exhibited a planar coordination structure in a high-temperature phase and a nonplanar structure in a low-temperature phase. The gradual spin transition is described as a spin equilibrium obeying the van’t Hoff law. Density functional theory calculation indicates that the energy level crossing of the high- and low-spin states. The optimized structures of diamagnetic and high-spin states well agreed with the experimental large and small torsions, respectively. The novel mechanism of the present spin transition lies in the ferro-/antiferromagnetic coupling switch. The entropy-driven mechanism is plausible after combining the results of the related copper(II)-nitroxide compounds. Attention must be paid to the coupling parameter J as a variable of temperature in the magnetic analysis of such spin-transition materials. For future work, the exchange coupling may be tuned by chemical modification and external stimulus, because it has been clarified that the parameter is sensitive to the coordination structure and actually varies from 2J/kB = +400 K to −1400 K.

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Structures and magnetic properties of two series of Schiff base binuclear lanthanide complexes

Ying

Huang

Zou

et al. 2022

Applied Organom Chemis

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Until now, although there are many examples of studying the magnetic properties of Schiff base binuclear lanthanide complexes, the relationship between the structure and magnetic properties of the complexes still is worth further investigation in order to improve the magnetic properties of Schiff base lanthanide complexes. In this work, we successfully obtained two series of binuclear Ln complexes by in situ reaction of 4‐diethylaminosalicylaldehyde, benzoic hydrazide and different lanthanide salts at 80°C under solvothermal conditions, namely, [Ln2(L)3(NO3)3]·CH3CN·CH3OH·H2O [Ln = Dy (1), Ho (2), Gd (3) L = deprotonated 4‐diethylamino salicylaldehyde benzoylhydrazine], [Ln2(L)4(CH3COO)]CH3COO·CH3CN [Ln = Dy (4), Ho (5), Gd (6)]. The complex 1 contains three Schiff base ligands L, two Dy (III) ions, and three NO3−. The ligand H1L is formed by in situ Schiff base reaction with 4‐diethylaminosalicylaldehyde and benzoic hydrazide with the participation of Ln (NO3)3. When replacing Ln (NO3)3 with Ln (OAc)3, obtained three μ2‐OAc bridged binuclear Ln (III) complexes. The magnetic study showed that complex 4 exhibits field‐induced single‐molecule magnet (SMM) behavior while complex 1 does not show any SMMs behavior. In addition, we have studied the magnetocaloric effect of complexes 3 and 6, their maximum −ΔSm values are 21.37 J kg−1 K−1 and 15.32 J kg−1 K−1, respectively, under ΔH = 7 T and T = 2 K.

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Gadolinium‐Triradical Complex with Ground S = 10 State: Synthesis, Structural Characterization and Magnetic Studies

Cited by 7 publications

References 55 publications

Ferromagnetic 2p-2p and 4f-2p Couplings in a Macrocycle from Two Biradicals and Two Gadolinium(III) Ions

Ferromagnetic 2p-2p and 4f-2p Couplings in a Macrocycle from Two Biradicals and Two Gadolinium(III) Ions

Molecular S = 2 High-Spin, S = 0 Low-Spin and S = 0 ⇄ 2 Spin-Transition/-Crossover Nickel(II)-Bis(nitroxide) Coordination Compounds

Structures and magnetic properties of two series of Schiff base binuclear lanthanide complexes

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