Production, Isolation, and Electronic Properties of Missing Fullerenes:  Ca@C₇₂ and Ca@C₇₄

Synthesis, isolation and characterization of new endohedral fullerenes M@C72 (M = Eu, Sr, Yb)

“…Both, Sr@C 72 -II and Yb@C 72 , do not show a prominent absorbtion in the UV-vis region. Furthermore, Eu@C 72 -I, Sr@C 72 -I and Yb@C 72 show a characteristic absorbtion within the NIR region at about 1400 nm, which also been reported for one of the Ca@C 72 -isomers [2]. The distinct absorptions at 1381 nm, 1360 nm and 1373 nm are caused by the difference in ionization energies of europium, strontium and ytterbium.…”

“…Two Ca@C 72 isomers have been isolated [2,3]. Based on theoretical calculations for Ca@C 72 and Mg@C 72 , four stable isomers have been predicted for each of them.…”

Computations on three isomers of La@C74

“…The computations treat a set of three metallofullerene isomers, using the carbon cages investigated [2,[21][22][23] with Ca@C 74 , namely the unique D 3h C 74 IPR cage and two non-IPR cages yielding nonnegligible computed metallofullerene concentrations. In the previous computations, the cages have been labeled by some code numbers that are also used here, combined with the symmetry of the empty cage: 1/D 3h , 103/C 1 , and 4/C 1 ( Fig.…”

“…W hile empty C 74 fullerene [1] has still not been available, various related C 74 -based metallo-fullerenes have been known and studied vigorously like Ca@C 74 [2,3], Sm@C 74 [4,5], Sr@C 74 [6], Ba@C 74 [7], La@C 74 [8][9][10], Eu@C 74 [11], Yb@C 74 [12][13][14], Sc 2 @C 74 [15], or Er 3 @C 74 [16]. Among them, La@C 74 has a special position as its X-ray crystallographic analysis is available [10], although for a solventrelated derivative, La@C 74 -C 6 H 3 Cl 2 .…”

“…First, such computations were performed for Ca@C 74 [2,[21][22][23], and it was shown that the non-IPR encapsulations are not significant for Ca@C 74 (in contrast to Ca@C 72 [25,26]). This paper deals with calculations of La@C 74 again from the point of view of possibilities for encapsulation into non-IPR C 74 cages, consistently using the Gibbs energies as required by high temperatures [27,28].…”