Lithium-ion-encapsulated fullerenes (Li
@C
) are 3D superatoms with rich oxidative states. Here we show a conductive and magnetically frustrated metal-fullerene-bonded framework {Cu
(Li@C
)(L)(py)
...(NTf
)(hexane)}
(1) (L = 1,2,4,5-tetrakis(methanesulfonamido)benzene, py = pyridine, NTf
= bis(trifluoromethane)sulfonamide anion) prepared from redox-active dinuclear metal complex Cu
(L)(py)
and lithium-ion-encapsulated fullerene salt (Li
@C
)(NTf
). Electron donor Cu
(L)(py)
bonds to acceptor Li
@C
via eight Cu‒C bonds. Cu-C bond formation stems from spontaneous charge transfer (CT) between Cu
(L)(py)
and (Li
@C
)(NTf
) by removing the two-terminal py molecules, yielding triplet ground state Cu
(L)(py)
(Li
@C
), evidenced by absorption and electron paramagnetic resonance (EPR) spectra, magnetic properties and quantum chemical calculations. Moreover, Li
@C
radicals (S = ½) and Cu
ions (S = ½) interact antiferromagnetically in triangular spin lattices in the absence of long-range magnetic ordering to 1.8 K. The low-temperature heat capacity indicated that compound 1 is a potential candidate for an S = ½ quantum spin liquid (QSL).
Using scanning tunneling microscopy (STM) and density functional theory (DFT) calculations, we directly determine the spatial and energetic distributions of superatom molecular orbitals (SAMOs) of an ...Li@C60 monolayer adsorbed on a Cu(111) surface. Utilizing a weakly bonded Li+@C60 NTf2 – (NTf2 –: bis(trifluoromethanesulfonyl)imide) salt makes it possible to produce a Li@C60 monolayer with high concentration of Li@C60 molecules. Because of the very uniform adsorption geometry of Li@C60 on Cu(111), the p z -SAMO, populated above the upper hemisphere of the molecule, exhibits an isotropic and delocalized nature, with an energy that is significantly lower compared to that of C60. The isotropic overlapping of p z -SAMOs in the condensed monolayer of Li@C60 results in a laterally homogeneous STM image contributing to the formation of a free-electron-like states. These findings make an important step toward further basic research and applicative utilization of Li@C60 SAMOs.
If the physical properties of C(60) fullerene molecules can be controlled in C(60) products already in use in various applications, the potential for industrial development will be significant. ...Encapsulation of a metal atom in the C(60) fullerene molecule is a promising way to control its physical properties. However, the isolation of C(60)-based metallofullerenes has been difficult due to their insolubility. Here, we report the complete isolation and determination of the molecular and crystal structure of polar cationic Li@C(60) metallofullerene. The physical and chemical properties of Li@C(60) cation are compared with those of pristine C(60). It is found that the lithium cation is located at off-centre positions in the C(60)-I(h) cage interior and that the Li(+)@C(60) salt has a unique two-dimensional structure. The present method of purification and crystallization of C(60)-based metallofullerenes provides a new C(60) fullerene material that contains a metal atom.
Covalently organic derivatization of Li+@C60PF6 – to obtain Li+-encapsulated PCBM, Li+@PCBMPF6 –, is described. Synthetic procedures, electrochemical properties, light absorption properties, details ...of isomerization from 5,6- to 6,6-isomer, and X-ray crystal structure of Li+@PCBMPF6 – are discussed.
Rock solid: Fullerene‐encapsulated Li+ (Li+@C60) is an alkaline cation owing to the spherical shape and positive charge. Li+@C60 crystallizes as a rock‐salt‐type crystal in the presence of PF6−. The ...orientations of C60 (green; see picture) and PF6− (orange) are perfectly ordered below 370 K, and Li+ (purple) hops within the cage. At temperatures below 100 K two Li+ units are localized at two polar positions within each C60.
Using scanning tunneling microscopy (STM) and density functional theory (DFT) calculations, we directly determine the spatial and energetic distributions of superatom molecular orbitals (SAMOs) of an ...Li@C-60 monolayer adsorbed on a Cu(111) surface. Utilizing a weakly bonded Li+@C-60 NTf2- (NTf2-: bis(trifluoromethanesulfonyl)imide) salt makes it possible to produce a Li@C-60 monolayer with high concentration of Li@C-60 molecules. Because of the very uniform adsorption geometry of Li@C-60 on Cu(111), the p(z)-SAMO, populated above the upper hemisphere of the molecule, exhibits an isotropic and delocalized nature, with an energy that is significantly lower compared to that of C-60. The isotropic overlapping of p(z)-SAMOs in the condensed monolayer of Li@C-60 results in a laterally homogeneous STM image contributing to the formation of a free-electron-like states. These findings make an important step toward further basic research and applicative utilization of Li@C-60 SAMOs.
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