W- and X-band EPR investigation of Sc3@C82

Rahmer, Jürgen; Dunsch, Lothar; Dorn, Harry C.; Mende, Jens; Mehring, M.

doi:10.1002/mrc.1665

Cited by 13 publications

(17 citation statements)

References 16 publications

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“…The best simulation was found with isotropic parameters of g = 2.00 and A = 18.10 MHz, which are identical to previous studies. 28 , 32 , 33 Upon cooling, 22 lines gradually disappeared and were replaced with a single 12 G wide line below 130 K. 28 This abrupt transformation of the cw-EPR spectra was largely due to the Sc 3 C 2 core motion. At above 140 K, mobility of the core was possible due to the weak interaction between the core and shell.…”

Section: Resultsmentioning

confidence: 99%

Qubit crossover in the endohedral fullerene Sc₃C₂@C₈₀

et al. 2018

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Section: Resultsmentioning

confidence: 99%

Qubit crossover in the endohedral fullerene Sc₃C₂@C₈₀

et al. 2018

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“…9,10 In the first studies of Sc 3 C 82 based on synchrotron powder diffraction measurements, 11 the molecule was considered to consist of three scandium atoms enclosed in a C 3v symmetric C 82 cage, denoted as Sc 3 @C 82 . Later EPR experiments on the molecule 12 partially supported this. Recently, 13 C NMR experiments have been performed on the corresponding [Sc 3 C 82 ] À anion, which is a closed-shell species.…”

Section: Introductionmentioning

confidence: 82%

“…Suggestions about the nature of the dynamics of confined metal atoms and small clusters inside fullerenes have been made, mainly based on NMR, 19 EPR 12,20,21 and Raman experiments. 22,23 A theoretical study further supported the Raman measurements.…”

Section: Introductionmentioning

confidence: 99%

Dynamics and magnetic resonance properties of Sc3C2@C80 and its monoanion

Taubert

Straka

Pennanen

et al. 2008

Phys. Chem. Chem. Phys.

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We report density functional theory (DFT) studies on the endohedral scandium carbide fullerene Sc3C2@C80 and its monoanion [Sc3C2@C80](-). The system consisting of a Sc3C2 moiety inside the Ih C80 fullerene has been studied by using first principles molecular dynamics simulations at the DFT level. On the picosecond time scale, the triangle defined by the scandium atoms is seen to jump between orientations along the equatorial six-membered ring belt of the cage. The confined carbide unit, in turn, is engaged in a flipping motion through the Sc3 plane. In contrast to the equilibrium geometry optimisations using large basis sets that predict a trigonal bipyramidal structure, a planar Sc3C2-moiety is preferred during the finite-temperature simulation. In the molecular dynamics picture, Sc3C2@C80 is best described as an equilibrium between the two static minimum structures. Calculations of the vibrational frequencies show that the earlier predicted C2 and C2v symmetric isomers are in fact saddle points, with one imaginary normal mode frequency that is related to the flipping motion of the confined carbon dimer. Reoptimisation revealed two new minimum energy structures where the C2 unit is tilted with respect to its orientation in the earlier suggested higher-symmetry structures. The nature of the bonding in the static structures of the two isomers of Sc3C2@C80 has been investigated using the electron localisation function and natural population analysis. Some increased electron pair localisation is detected on the six-membered rings closest to the Sc atoms. 13C nuclear magnetic resonance (NMR) chemical shifts have been calculated for the closed-shell monoanion of Sc3C2@C80. The 13C shifts were also calculated for Sc2C2@C84, for further comparison to experimentally measured spectra. The confined carbon atoms are strongly deshielded in these metallofullerenes, implying an incorrect earlier interpretation of the experimental 13C NMR spectrum of Sc2C2@C84. The neutral Sc3C2@C80 system with one unpaired electron is further characterised by calculating the hyperfine coupling constants, the g tensor, as well as paramagnetic NMR (pNMR) 13C shifts for both static isomers. The chemical shifts of the confined carbon atoms and the hyperfine coupling constants of all the confined atoms are strongly dependent on the conformation of the Sc3C2 moiety. Consequently, dynamical effects are expected to be important in the modelling of the magnetic properties of endohedral scandium carbide fullerenes. The two low-lying isomers have rather different pNMR 13C shifts, implying the potential of this method in structural assignment.

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“…Freezing of the cluster, on the other hand, leads to a dramatic broadening of the EPR features, which precludes observation of the hyperfine structure. The disappearance of the hyperfine splitting and the evolution of the spectrum into one broad feature at a similar temperature was observed earlier for Sc 3 C 2 @C 80 …”

Section: Resultsmentioning

confidence: 99%

“…The disappearance of the hyperfines plitting and the evolution of the spectrum into one broad feature at as imilart emperature was observed earlier for Sc 3 C 2 @C 80 . [33] Scandium-containing endometallofullerenes were previously studied mainly in solution. The preparationo fs alt 6 allowed the analysiso ft he EPR spectrumo fS c 3 N@I h -C 80 C À in the solid state.…”

Section: Dissociation Of Singly Bonded (Scmentioning

confidence: 99%

Molecular Structure and Magnetic and Optical Properties of Endometallonitridofullerene Sc₃N@I_h‐C₈₀ in Neutral, Radical Anion, and Dimeric Anionic Forms

Konarev

Popov

Zorina

et al. 2019

Chemistry A European J

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A series of compounds with Sc3N@Ih‐C80 in the neutral, monomeric, and dimeric anion states have been prepared in the crystalline form and their molecular structures and optical and magnetic properties have been studied. The neutral Sc3N@Ih‐C80⋅3 C6H4Cl2 (1) and (Sc3N@Ih‐C80)3(TPC)2⋅5 C6H4Cl2 (2, TPC=triptycene) compounds both crystallized in a high‐symmetry trigonal structure. The reduction of Sc3N@Ih‐C80 to the radical anion resulted in dimerization to form diamagnetic singly bonded (Sc3N@Ih‐C80−)2 dimers. In contrast to {[2.2.2]cryptand(Na+)}2(Sc3N@Ih‐C80−)2⋅2.5 C6H4Cl2 (3) with strongly disordered components, we synthesized new dimeric phases {[2.2.2]cryptand‐ (K+)}2(Sc3N@Ih‐C80−)2⋅2 C6H4Cl2 (4) and {[2.2.2]cryptand‐ (Cs+)}2(Sc3N@Ih‐C80−)2⋅2 C6H4Cl2 (5) in which only one major dimer orientation was found. The thermal stability of the (Sc3N@Ih‐C80−)2 dimers was studied by EPR analysis of 3 to show their dissociation in the 400–460 K range producing monomeric Sc3N@Ih‐C80.− radical anions. This species shows an EPR signal with a hyperfine splitting of 5.8 mT. The energy of the intercage C−C bond was estimated to be 234±7 kJ mol−1, the highest value among negatively charged fullerene dimers. The EPR spectra of crystalline (Bu3MeP+)3(Sc3N@Ih‐C80.−)3⋅C6H4Cl2 (6) are presented for the first time. The salt shows an asymmetric EPR signal, which could be fitted by three lines. Two lines were attributed to Sc3N@Ih‐C80.−. Hyperfine splitting is manifested above 180 K due to the hyperfine interaction of the electron spin with the three scandium atoms (a total of 22 lines with an average splitting of 5.32 mT are observed at 220 K). Furthermore, each of the 22 lines is additionally split into six lines with an average separation of 0.82 mT. The large splitting indicates intrinsic charge and spin density transfer from the fullerene cage to the Sc3N cluster. Both the monomeric and dimeric Sc3N@Ih‐C80− anions show an intrinsic shift of the IR bands attributed to the Sc3N cluster and new bands corresponding to these species appear in the NIR range of their UV/Vis/NIR spectra, which allows these anions to be distinguished from neutral species.

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W- and X-band EPR investigation of Sc3@C82

Cited by 13 publications

References 16 publications

Qubit crossover in the endohedral fullerene Sc₃C₂@C₈₀

Qubit crossover in the endohedral fullerene Sc₃C₂@C₈₀

Dynamics and magnetic resonance properties of Sc3C2@C80 and its monoanion

Molecular Structure and Magnetic and Optical Properties of Endometallonitridofullerene Sc₃N@I_h‐C₈₀ in Neutral, Radical Anion, and Dimeric Anionic Forms

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W- and X-band EPR investigation of Sc3@C82

Cited by 13 publications

References 16 publications

Qubit crossover in the endohedral fullerene Sc3C2@C80

Qubit crossover in the endohedral fullerene Sc3C2@C80

Dynamics and magnetic resonance properties of Sc3C2@C80 and its monoanion

Molecular Structure and Magnetic and Optical Properties of Endometallonitridofullerene Sc3N@Ih‐C80 in Neutral, Radical Anion, and Dimeric Anionic Forms

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Product

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Qubit crossover in the endohedral fullerene Sc₃C₂@C₈₀

Qubit crossover in the endohedral fullerene Sc₃C₂@C₈₀

Molecular Structure and Magnetic and Optical Properties of Endometallonitridofullerene Sc₃N@I_h‐C₈₀ in Neutral, Radical Anion, and Dimeric Anionic Forms