Structure and Magnetic Properties of Lanthanide Compounds with the 3,6-Di(Tert-Butyl)-1,2-Benzoquinone Radical Anion

Романенко, Г. В.; Fokin, S. V.; Letyagin, G. A.; Bogomyakov, A. S.; Овчаренко, В. И.

doi:10.1134/s0022476619070102

Cited by 8 publications

(8 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The shift reagents for NMR spectroscopy tris(1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-octanedionate)europium(III) {[Eu(fod) 3 ]}, 2,2′-dipyridyl (Dipy), pyridine (Py), and THF from Sigma-Aldrich were used as received. Heterospin complex [Eu(SQ) 3 (THF) 2 ] was prepared by direct interaction of 3,6-di( tert -butyl)-1,2-benzoquinone (Q) with an excess of metallic Eu in THF and purified by a procedure reported elsewhere . Chemical synthesis and all other manipulations were carried out in a dry argon atmosphere of the MBraun drybox LABmaster dp (H 2 O < 3 × 10 –4 %).…”

Section: Methodsmentioning

confidence: 99%

“…Heterospin complex [Eu(SQ) 3 (THF) 2 ] was prepared by direct interaction of 3,6di(tert-butyl)-1,2-benzoquinone (Q) with an excess of metallic Eu in THF and purified by a procedure reported elsewhere. 29 Chemical synthesis and all other manipulations were carried out in a dry argon atmosphere of the MBraun drybox LABmaster dp (H 2 O < 3 × 10 −4 %). Microanalyses were performed on the EA-3000 CHNS analyzer.…”

Section: Methodsmentioning

confidence: 99%

“…In this work, we present a proton NMR study of solutions of heterospin complex [Eu(SQ) 3 L n ], where SQ is 3,6-di( tert -butyl)semiquinone, L is tetrahydrofuran (THF), Py, or Dipy, n is the number of diamagnetic ligands. The X-ray structure of the [Eu(SQ) 3 (THF) 2 ] complex reported recently by some of us is given in Figure . The NMR study was performed at variable magnetic field strengths (4.7, 9.4, and 16.4 T) with the aim of probing the magnetic field effect on NMR line broadening.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Multifrequency Nuclear Magnetic Resonance as an Efficient Tool To Investigate Heterospin Complexes in Solutions

et al. 2020

View full text Add to dashboard Cite

We report a multifrequency nuclear magnetic resonance (NMR) study of heterospin complexes [Eu(SQ)3L n ], where SQ is 3,6-di(tert-butyl)-1,2-semiquinone, L is tetrahydrofuran (THF), pyridine (Py), or 2,2′-dipyridyl (Dipy), and n is the number of diamagnetic ligands. Multifrequency NMR experiments allowed us to determine the effective paramagnetic shifts of the ligands (L = THF or Py) and the chemical equilibrium constant for [Eu(SQ)3(THF)2]. In addition, we have found a strong magnetic field effect on the NMR line broadening, giving rise to very broad NMR lines at high magnetic fields. We attribute this effect to broadening under fast exchange conditions when the NMR spectrum represents a homogeneously broadened line with a width proportional to the square of the NMR frequency difference of the free and bound forms of L. Consequently, the line width strongly increases with the magnetic field. This broadening effect allows one to determine relevant kinetic parameters, i.e., the effective exchange time. The strong broadening effect allows one to exploit the [Eu(SQ)3(THF)2] complex as an efficient shift reagent, which not only shifts unwanted NMR signals but also broadens them, notably, in high-field NMR experiments. We have also found that [Eu(SQ)3Dipy] is a thermodynamically stable complex; hence, one can study [Eu(SQ)3Dipy] solutions without special precautions. We report an X-ray structure of the [Eu(SQ)3Dipy]·C6D6 crystals that have been grown directly in an NMR tube. This shows that multifrequency NMR investigations of heterospin compound solutions not only provide thermodynamic and kinetic data for heterospin species but also can be useful for the rational design of stable heterospin complexes and optimization of synthetic approaches.

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Multifrequency Nuclear Magnetic Resonance as an Efficient Tool To Investigate Heterospin Complexes in Solutions

et al. 2020

View full text Add to dashboard Cite

show abstract

“…As the ac magnetic susceptibility data were measured in an external applied field, we may consider the QTM to be quenched, and as such a fit was performed with a combination of direct relaxation and Raman relaxation processes (fit 1, 5). This fit gives A = 2181(67) K À 1 , C = 0.135(6) s À 1 K À n , and n = 8.57 (32). However, the lowest temperature data are not well fit.…”

Section: Dynamic Magnetometrymentioning

confidence: 97%

“…[24,25] In Ln(III) molecular chemistry, tetraoxolene ligands have been used to bridge Ln(III) ions in dinuclear species, with the tetraoxolene in both the diamagnetic and radical forms, [26][27][28] while diamagnetic catecholate ligands have been utilized in both Ln(III) SMM [29][30][31] and other Ln compounds. [32][33][34][35] One group of compounds for which the Ln(III)-dioxolenes are isolable in their semiquinonate redox form are the family of compounds [Ln(Tp) 2 (DBSQ)] (Tp À = hydro-tris(1-pyrazolyl)borate, DBSQ• À = 3,5-di-tertbutyl-1,2-semiquinonate). [36,37] Notably, the Gd(III) analogue has a relatively large antiferromagnetic magnetic exchange coupling of J ex = À 5.7 cm À 1 between the Gd(III) and the DBSQ• À ligand.…”

Section: Introductionmentioning

confidence: 99%

Modulation of Slow Magnetic Relaxation in Gd(III)‐Tetrahalosemiquinonate Complexes

Dunstan

Brown

Sorace

et al. 2022

Chemistry An Asian Journal

View full text Add to dashboard Cite

Incorporating lanthanoid(III)‐radical magnetic exchange coupling is a possible route to improving the performance of lanthanoid (Ln) single‐molecule magnets (SMMs), molecular materials that exhibit slow relaxation and low temperature quantum tunnelling of the magnetization. Complexes of Gd(III) can conveniently be used as model systems to study the Ln‐radical exchange coupling, thanks to the absence of the orbital angular momentum that is present for many Ln(III) ions. Two new Gd(III)‐radical compounds of formula [Gd(18‐c‐6)X4SQ(NO3)].I3 (18‐c‐6=18‐crown‐6, X4SQ⋅−=tetrahalo‐1,2‐semiquinonate, 1: X=Cl, 2: X=Br) have been synthesized, and the presence of the dioxolene ligand in its semiquinonate form confirmed by X‐ray crystallography, UV‐Visible‐NIR spectroscopy and voltammetry. Static magnetometry and EPR spectroscopy indicate differences in the low temperature magnetic properties of the two compounds, with antiferromagnetic exchange coupling of JGd‐SQ∼−2.0 cm−1 (Hex=−2JGd‐SQ(SGdSSQ)) determined by data fitting. Interestingly, compound 1 exhibits slow magnetic relaxation in applied magnetic fields while 2 relaxes much faster, pointing to the major role of packing effects in modulating slow relaxation of the magnetization.

show abstract

Structural Variety, Isomerism, and Interconversions of Polynuclear Samarium Complexes with Reduced 9,10-Phenanthrenequinone Ligand

Sinitsa,

Sukhikh,

Konchenko

et al. 2024

Organometallics

View full text Add to dashboard Cite

The reaction of samarocene [SmCp* 2 (thf) n ] (1, Cp* = η 5 -C 5 Me 5 , thf = tetrahydrofuran, n = 0, 2) with a redoxactive ligand 9,10-phenanthrenequinone (phenQ) was investigated. Reaction products strongly depend on the reactant ratio and the presence of donor solvent (thf). The 1:1 reaction in toluene leads to the trinuclear complex [Sm 3 Cp* 3 (phenCat) 3 ] (4, phenCat 2− is a doubly reduced form of phenQ), while in thf, the binuclear complex [Sm 2 Cp* 2 (phenCat) 2 (thf) 3 ] ( 5) is formed with the same metal-to-ligands ratio Sm:Cp*:phenCat = 1:1:1. The same reaction in hexane leads to a mixture of products with a greater number of {SmCp* 2 } fragments; the major ones are the binuclear complex [Sm 2 Cp* 4 (phenCat)] (6) and the heterovalent complex [Sm 3 Cp* 4 (phenCat) 2 ] (7), and the minor product is the complex salt [SmCp* 2 ] + [Sm 2 Cp* 3 (phenCat) 2 ] − ([SmCp* 2 ][8] − ). Sm 2+ in all cases and the Cp* − ligand in most cases are oxidized. Simultaneous crystallization of two stable geometrical isomers of 7 was discovered, differing in the position of one phenCat 2− ligand. For the reactions in toluene, several byproducts were found: two structurally equivalent complexes with the anion 8 − as the sole ligand, [Sm(8) 2 ] (9) and [K(8) 2 ] − (10 − , crystallized with the samarocenium cation), and a cocrystal of two neutral complexes [Sm 2 Cp* 3 (phenCat)(thf)(μ-OH)] 2 [Sm 4 Cp* 4 (phenCat) 4 ] ((11) 2 12). Complex 12 has the same metal-to-ligands ratio as 4 but has a different total composition. The single-crystal structures are compared with the known ones for bulkier 3,6-bis-t-butyl-obenzoquinone and reveal a crucial influence of ligand steric properties and interligand π-stacking on the geometry and composition of the complexes.

show abstract

Structure and Magnetic Properties of Lanthanide Compounds with the 3,6-Di(Tert-Butyl)-1,2-Benzoquinone Radical Anion

Cited by 8 publications

References 19 publications

Multifrequency Nuclear Magnetic Resonance as an Efficient Tool To Investigate Heterospin Complexes in Solutions

Multifrequency Nuclear Magnetic Resonance as an Efficient Tool To Investigate Heterospin Complexes in Solutions

Modulation of Slow Magnetic Relaxation in Gd(III)‐Tetrahalosemiquinonate Complexes

Structural Variety, Isomerism, and Interconversions of Polynuclear Samarium Complexes with Reduced 9,10-Phenanthrenequinone Ligand

Contact Info

Product

Resources

About