2‐Aminoethanol Extraction as a Method for Purifying Sc₃N@C₈₀ and for Differentiating Classes of Endohedral Fullerenes on the Basis of Reactivity

Abstract

Extraction with 2-aminoethanol is an inexpensive method for removing empty cage fullerenes from the soluble extract from electric-arc-generated fullerene soot that contains endohedral metallofullerenes of the type Sc3N@C2n (n = 34, 39, 40). Our method of separation exploits the fact that C60, C70, and other larger, empty cage fullerenes are more susceptible to nucleophilic attack than endohedral fullerenes and that these adducts can be readily extracted into 2-aminoethanol. This methodology has also been employed to examine the reactivity of the mixture of soluble endohedral fullerenes that result from doping graphite rods used in the Krätschmer-Huffman electric-arc generator with the oxides of Y, Lu, Dy, Tb, and Gd. For example, with Y2O3, we were able to detect by mass spectrometry several new families of endohedral fullerenes, namely Y3C108 to Y3C126, Y3C107 to Y3C125, Y4C128 to Y4C146, that resisted reactivity with 2-aminoethanol more than the empty cage fullerenes and the mono- and dimetallo fullerenes. The discovery of the family Y3C107 to Y3C125 with odd numbers of carbon atoms is remarkable, since fullerene cages must involve even numbers of carbon atoms. The newly discovered families of endohedral fullerenes with the composition M4C2n (M = Y, Lu, Dy, Tb, and Gd) are unusually resistant to reaction with 2-aminoethanol. Additionally, the individual endohedrals, Y3C112 and M3C102 (M = Lu, Dy, Tb and Gd), were remarkably less reactive toward 2-aminoethanol.

Synthesis and Isolation of the Titanium–Scandium Endohedral Fullerenes—Sc2TiC@Ih‐C80, Sc2TiC@D5h‐C80and Sc2TiC2@Ih‐C80: Metal Size Tuning of the TiIV/TiIIIRedox Potentials

“…[28b] They serve as potential models for the series of EMFs with odd numbers of carbon atoms such as Y 3 C 107 to Y 3 C 125 and Lu 3 C 107 to Lu 3 C 115 ,w hich have been discovered recently. [42] The presence of methane in the reactor atmosphere is crucial for the high selectivity of the synthesis of carbidec lusterfullerenes. In particular,i td ramatically reduces the yield of empty fullerenes.…”

Piperazine Functionalization of C70 for Incorporation into Supramolecular Assemblies

“…Along the chain the AgÀNd istances fall in av ery narrow range, 2.267(15)t o2 .307 (16) .T he Ag-N-Aga ngles also fall in an arrow range, 170.1 to 170.78,t hat produces only as light kinking of the chain. Therea re four molecules of the adduct N(CH 2 CH 2 ) 2 NC 70 (labeledA ,B ,Cand D) and four silver nitrate entitiesa long with seven dichloromethane molecules in the asymmetricu nit.…”

“…Remarkably,i n contrastt ot he {Rh 2 (O 2 CCF 3 ) 4 N(CH 2 CH 2 ) 2 NC 70 } n ·nC 6 H 6 structure, each of the four fullerenec ages in this silver polymer is ordered. Along the chain the AgÀNd istances fall in av ery narrow range, 2.267(15)t o2 .307 (16) .T he Ag-N-Aga ngles also fall in an arrow range, 170.1 to 170.78,t hat produces only as light kinking of the chain. In addition to coordination to nitrogen, each silver ion is also located near nitrate ions.…”

Identifying a Needle in a Haystack: Isolation and Structural Characterization of Er2C94 as the Carbide Er2C2@D3(85)‐C92

“…These fullerenes are usually prepared by the Krätschmer–Huffman electric‐arc process, which generally produces a number of soluble compounds that include empty‐cage fullerenes, as well as an array of endohedral metallofullerenes. Separation of the individual components can be time consuming, although a number of chemical methods for isolation of various types of fullerenes have been developed …”

“…Separation of the individual components can be time consuming, although a number of chemical methods for isolation of varioust ypes of fullerenes have been developed. [11][12][13][14][15][16] Structural characterization of endohedralm etallofullerenes runs into issues involving cage structurea nd cage isomers. While empty-cage fullerenes obey the isolated pentagonr ule (IPR), whichs pecifies that each of the twelve pentagons in a fullerenei ss urrounded by five hexagons,t his rule is only a suggestion for endohedral metallofullerenes.…”