<i>Ab initio</i>-based determination of lanthanoid–radical exchange as visualised by inelastic neutron scattering

Dunstan, Maja A.; Giansiracusa, Marcus J.; Calvello, Simone; Sorace, Lorenzo; Krause-Heuer, Anwen M.; Soncini, Alessandro; Mole, Richard A.; Boskovic, Colette

doi:10.1039/d3sc04229d

Cited by 3 publications

(4 citation statements)

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“…Data for the Er analogues were reported previously and are included for comparison. [10] All Lntrop are isomorphous, crystallizing in the chiral space groups P4 1 2 1 2 and P4 3 2 1 2 with half a complex per unit cell, consistent with a previously reported Ho analogue. [9] The Ln-dbsq series are also isomorphous, crystallizing in the space group P2 1 /c.…”

Section: Crystallography and Structure Descriptionsupporting

confidence: 86%

“…This structural similarity between the two analogues supports the assumption of similar ligand geometry and therefore crystal-field effects for the analysis of spectroscopic and magnetic data. [10]…”

Section: Crystallography and Structure Descriptionmentioning

confidence: 99%

“…Building on an early study from Caneschi et al, [9] we have recently reported elucidation of the exchange coupling between an Er(III) ion and the 3,5-di-tertbutylseminquinonate (dbsq *À ) radical ligand in the complex [ErTp 2 dbsq] (Tp À = hydro-tris(1pyrazolyl)borate) in a combined experimental and computational investigation. [10] This determination relied upon comparison of the electronic structure with an analogue containing the non-radical tropolonate (trop À ) ligand in the complex [ErTp 2 trop], and the assumption that the crystal field splitting of the Er(III) ions is similar in both complexes due to the near identical Er(III) coordination geometry.…”

Section: Introductionmentioning

confidence: 99%

“…Although the magnetic properties of many of the lanthanoid complexes in the families [LnTp 2 dbsq] (Ln-dbsq) and [LnTp 2 trop] (Ln-trop) were reported some time ago, and our own recent study involved inelastic neutron scattering and EPR spectra, [10] these data have all been collected in the solid state. Solution data are largely absent for these complexes, including the electrochemical and photophysical properties.…”

Section: Introductionmentioning

confidence: 99%

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Lanthanoid Semiquinonate/Tropolonate Complexes: Redox Chemistry and Luminescence

Dunstan,

Suryadevara,

Cameron

et al. 2024

Eur J Inorg Chem

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Heteroleptic lanthanoid (Ln = Eu, Gd, Tb, Dy, Ho and Yb) complexes featuring hydro‐tris(1‐pyrazolyl)borate (Tp−) ligands combined with the bidentate O‐donor ligands tropolonate (trop−) or 3,5‐di‐tertbutylseminquinonate (dbsq●−) have been synthesized and investigated. Despite the similarity of the bidentate O‐donor trop− and dbsq●− ligands, and the lanthanoid coordination geometries, the complexes [LnTp2dbsq] (Ln‐dbsq) and [LnTp2trop] (Ln‐trop) exhibit markedly different redox and photophysical properties. The electrochemistry of Ln‐dbsq is dominated by processes associated with the readily redox‐active dbsq●− moiety. In contrast, the relative redox inactivity in Ln‐trop allows for the observation of the Eu(III) to Eu(II) reduction process. Photophysical measurements reveal no sensitized emission for the Ln‐dbsq family, while the trop− antenna ligand is able to sensitize emission in the visible range for Eu(III) and Ho(III), and in the near‐infrared for Ho(III) and Yb(III).

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Section: Crystallography and Structure Descriptionsupporting

confidence: 86%

Section: Crystallography and Structure Descriptionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Lanthanoid Semiquinonate/Tropolonate Complexes: Redox Chemistry and Luminescence

Dunstan,

Suryadevara,

Cameron

et al. 2024

Eur J Inorg Chem

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Trigonal Planar Heteroleptic Lanthanide(III) Bis(silyl)amide Complexes Containing Aminoxyl Radicals and Anions

Gransbury,

Nicholas,

Murphy

et al. 2024

Inorg. Chem.

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Modulation of the crystal field (CF) in lanthanide (Ln) complexes can enhance optical and magnetic properties, and large CF splitting can be achieved with low coordination numbers in specific geometries. We previously reported that the homoleptic near-linear Sm 2+ complex [Sm II {N(Si i Pr 3 ) 2 } 2 ] (1-Sm) is oxidized by the 2,2,6,6-tetramethylpiperidinyl-1-oxy (TEMPO • ) radical to give the heteroleptic, approximately trigonal planar Sm 3+ complex, [Sm III {N(Si i Pr 3 ) 2 } 2 (TEMPO − )] ( 2-Sm). Here, we report the synthesis of homologous [Ln III {N(Si i Pr 3 ) 2 } 2 (TEMPO − )] (2-Ln; Ln = Tm, Yb) complexes by the oxidation of the parent [Ln{N(Si i Pr 3 ) 2 } 2 ] (1-Ln; Ln = Tm, Yb) with TEMPO • ; complexes 2-Ln all contain TEMPO − anions. The homoleptic bent Ln 3+ complexes [Ln III {N(Si i Pr 3 ) 2 } 2 ][B(C 6 F 5 ) 4 ] (3-Ln; Ln = Sm, Tm, Yb) were also treated with TEMPO • to yield the heteroleptic, approximately trigonal planar Ln 3+ complexes [Ln III {N(Si i Pr 3 ) 2 } 2 (TEMPO • )][B(C 6 F 5 ) 4 ] (4-Ln; Ln = Sm, Tm, Yb); the cations of 4-Ln all contain TEMPO • radicals. We have compared the electronic structures of the two geometrically similar families of Ln 3+ complexes with the TEMPO − anion (2-Ln) or TEMPO • radical (4-Ln) using a combination of UV−vis-NIR and EPR spectroscopy, magnetic measurements, and ab initio calculations. These studies revealed no single-molecule magnet behavior for 2-Yb despite evidence for sizable CF splitting and a high degree of purity of the ground stabilized m J = |±7/2⟩ state, while the radical TEMPO • in 4-Yb did not significantly improve performance.

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Isolation of Elusive Fluoflavine Radicals in Two Differing Oxidation States

Benner,

Demir

2024

J. Am. Chem. Soc.

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Facile access and switchability between multiple oxidation states are key properties of many catalytic applications and spintronic devices yet poorly understood due to inherent complications arising from isolating a redox system in multiple oxidation states without drastic structural changes. Here, we present the first isolable, free fluoflavine (flv) radical flv(1–•) as a bottleable potassium compound, [K(crypt-222)](flv•), 1, and a new series of organometallic rare earth complexes [(Cp*2Y)2(μ-flvz)]X, (where Cp* = pentamethylcyclopentadienyl, X = [Al(OC{CF3}3)4]− (z = −1), 2; X = 0 (z = −2), 3; [K(crypt-222)]+ (z = −3), 4) comprising the flv ligand in three different oxidation states, two of which are paramagnetic flv1–• and flv3–•. Excitingly, 1, 2, and 4 constitute the first isolable flv1–• and flv3–• radical complexes and, to date, the only isolated flv radicals of any oxidation state. All compounds are accessible in good crystalline yields and were unambiguously characterized via single-crystal X-ray diffraction analysis, cyclic voltammetry, IR-, UV–vis, and variable-temperature EPR spectroscopy. Remarkably, the EPR spectra for 1, 2, and 4 are distinct and a testament to stronger spin delocalization onto the metal centers as a function of higher charge on the flv radical. In-depth analysis of the electron- and spin density via density functional theory (DFT) calculations utilizing NLMO, QTAIM, and spin density topology analysis confirmed the fundamental interplay of metal coordination, ligand oxidation state, aromaticity, covalency, and spin density transfer, which may serve as blueprints for the development of future spintronic devices, single-molecule magnets, and quantum information science at large.

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Ab initio-based determination of lanthanoid–radical exchange as visualised by inelastic neutron scattering

Abstract: Magnetic exchange coupling can modulate the slow magnetic relaxation in single-molecule magnets. Despite this, elucidation of exchange coupling remains a significant challenge for the lathanoid(III) ions, both experimentally and computationally....

Cited by 3 publications

References 81 publications

Lanthanoid Semiquinonate/Tropolonate Complexes: Redox Chemistry and Luminescence

Lanthanoid Semiquinonate/Tropolonate Complexes: Redox Chemistry and Luminescence

Trigonal Planar Heteroleptic Lanthanide(III) Bis(silyl)amide Complexes Containing Aminoxyl Radicals and Anions

Isolation of Elusive Fluoflavine Radicals in Two Differing Oxidation States

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