Yttrium in fullerenes

The study of the literature data showed that yttrium is encapsulated in fullerene molecules in the form of metal atoms, clusters of nitrides, carbides, sulfides and other compounds. Endohedral metallofullerenes are capable of encapsulating up to four metal atoms. In the molecules of these compounds, the metal atoms are positively charged due to the transfer of an electron from the endohedral metal atom to the fullerene carbon cage. First of all, the main experimental and theoretical achievements described in early (up to 2000) works are considered. Achievements in the production, separation (isolation) and various spectroscopic characteristics of endohedral metallofullerenes have been thoroughly studied in an attempt to elucidate their structural, electronic, and solid-state properties. It is shown that endohedral metallofullerenes in electrical conductivity can be metals, semiconductors with small gaps, or insulators, depending on the size of the fullerene, the type and number of encapsulated metal atoms. Other electronic and magnetic properties of metallofullerenes are also interesting. Also, some promising applications of metallofullerenes are considered.
In addition, when analyzing the literature on the synthesis and properties of metalloendofullerenes, a very large number of publications related to the exohedral functionalization of metallofullerenes attracts attention.
First of all, it should be noted that the main problem hindering the development of science, technology and the use of fullerenes, endohedral metallofullerenes and nanotubes was the difficulty of obtaining high-purity samples. When metals are introduced into the electric arc process, the situation becomes more complicated due to the presence of many isomers of both fullerenes and endohedral metallofullerenes. Exohedral functionalization helps to solve the problem of separation of synthesis products, on the one hand, and leads to the production of substances with new useful properties and potential applications in materials science and medicine.
It is noted that currently the most productive and widespread method for the production of endohedral fullerenes is the electric arc process. The quantitative and qualitative output of metallofullerenes is significantly influenced by the conditions of the process in the reactor.

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