Lanthanum Endohedral Metallofulleropyrrolidines: Synthesis, Isolation, and EPR Characterization

Abstract

Lanthanum endohedral metallofulleropyrrolidines have been synthesized for the first time through addition of an azomethine ylide to La@C82‐A in toluene. It was found that the addition reaction is very efficient and, to some extent, regioselective. Two major endohedral metallofulleropyrrolidines, a monoadduct and a bisadduct of La@C82‐A with abundance ratio of ∼1:0.4, have been isolated by HPLC chromatography and characterized by mass spectrometry, UV/Vis‐NIR absorption, and EPR spectroscopy. The electronic structure of La@C82‐A has been modified slightly upon monoaddition and significantly upon bisaddition of the pyrrolidines.

Chemical, Electrochemical, and Structural Properties of Endohedral Metallofullerenes

“…However, the hyperfine coupling constant, g value, and peak-to-peak linewidth of the monoadduct were closer to that of the nonderivatized La@C 82 (C 2v ) than that of the bisadduct, thus indicating that the monoadduct had a similar electronic structure to that of the parent compound. [49] In the same year, Gu and co-workers studied the same reaction with different M@C 82 EMFs (M = Gd, Y) [50,51] by using N-methylglycine and different aldehydes. Multiple additions were obtained and further isolation of the adducts was not accomplished.…”

“…[49] A solution of La@C 82 (C 2v ) in toluene containing an excess of N-methylglycine and paraformaldehyde was heated in a sealed EPR quartz tube at 100 8C for 30 minutes. Three bisadducts and two monoadducts were obtained, and multistep HPLC separation enabled one mono-and one bisadduct to be isolated in pure form.…”

Water-soluble fullerenes for medical applications

“…46 Prato reactions have been carried out on La@C 82 to yield mono-and bis-adducts, with electron paramagnetic resonance measurements showing slight modification of the electronic structure upon monoaddition, and significant modification upon bisaddition. 56 Bingel cyclopropanation was used by Bolskar et al 57 to isolate a derivative of the otherwise insoluble Gd@C 60 . This is of value as the Gd@C 60 fraction of the arc discharge soot is more abundant than Gd@C 82 but could never be isolated due to its insolubility.…”

Trifluoromethylated Endohedral Metallofullerenes: Synthesis and Characterization of Y@C82(CF3)5

“…Previously reported EMF cycloaddition products retained the paramagnetic nature of the parent EMFs, and routine NMR spectroscopic characterization was not possible. [17] Both isomers of Y@C 82 (CF 3 ) 5 exhibited a 19 F NMR spectrum with five resonances having a 1:1:1:1:1 intensity pattern. The d values for isomer II ranged from d = À53 to À69 ppm, which is similar to the d values for C 60 (CF 3 ) 2/4/6 (which ranged from d = À66 to À72 ppm).…”