Crystalline functionalized endohedral C60 metallofullerides

Abstract

Endohedral metallofullerenes have been extensively studied since the first experimental observation of La@C60 in a laser-vaporized supersonic beam in 1985. However, most of these studies have focused on metallofullerenes larger than C60 such as (metal)@C82, and there are no reported purified C60-based monomeric metallofullerenes, except for [Li@C60]+(SbCl6)− salt. Pure (metal)@C60 compounds have not been obtained because of their extremely high chemical reactivity. One route to their stabilization is through chemical functionalization. Here we report the isolation, structural determination and electromagnetic properties of functionalized crystalline C60-based metallofullerenes Gd@C60(CF3)5 and La@C60(CF3)5. Synchrotron X-ray single-crystal diffraction reveals that La and Gd atoms are indeed encapsulated in the Ih-C60 fullerene. The HOMO-LUMO gaps of Gd@C60 and La@C60 are significantly widened by an order of magnitude with addition of CF3 groups. Magnetic measurements show the presence of a weak antiferromagnetic coupling in Gd@C60(CF3)3 crystals at low temperatures.

Determining addition pathways and stable isomers for CF 3 functionalization of endohedral Gd@C 60

“…Fullerenes at the bottom of the figure where further addition is unfavourable have shaded backgrounds and a dark outline, and represent stable end points of a reaction pathway (adapted from Nakagawa et al . [ 6 ]). …”

“…In these cases, functionalization removes dangling bond or gap states, opening the energy gap between highest occupied (HOMOs) and lowest unoccupied (LUMOs) molecular orbitals and stabilizing the species [ 2 – 5 ]. In a similar way, functionalization has been proposed as a route to stabilization of certain metallic endofullerenes [ 5 , 6 ]. Introduction of a metallic atom within the cage can sometimes result in a locally reactive cage surface, which results in aggregation and hinders isolation and separation of the metallofullerene species.…”

Characterizing complexity of many-body quantum dynamics by higher-order eigenstate thermalization

“…th (X) follows a universal formula of the 2-REE of thermal pure states, which has been proposed in Refs [42,43]. It is written as…”

“…(74) have been obtained in Ref. [42][43][44] by using random pure states. In contrast to the case of k = 2, the finite-temperature Page correction of the 3-REE (i.e., the second term of Eq.…”

“…Thus, we see that the Page correction for a single energy eigenstate is understood as a unique contribution from the higher-order ETH. More generally, the finite-temperature Page curve of the k-REE [42][43][44] is obtained from the k-ETH at finite temperature. By using numerical exact diagonalization, we verified that the 2-ETH holds for the XXZ ladder model [45][46][47].…”