Synthesis, Isolation, and Trifluoromethylation of Two Isomers of C84 -Based Monometallic Cyanide Clusterfullerenes: Interplay between the Endohedral Cluster and the Exohedral Addends.

As an emerging member of endohedral fullerenes, metal cyanide clusterfullerenes (CYCF) are unique in terms of the encapsulation of a monometallic cluster. To date the reported carbon cages of CYCFs are limited to C82 and C76 , and little is known about the chemical reactivity of CYCFs. Herein, two isomers of the first C84 -based CYCFs, YCN@C84 , were isolated as trifluoromethyl derivatives, including YCN@C84 (23)(CF3 )18 and three isomers of YCN@C84 (13)(CF3 )16 , which are based on a unique chiral C2 -C84 (13) cage. As a common feature of the CF3 addition patterns, the YCN@C84 (CF3 )16/18 compounds are stabilized by the formation of isolated C=C bonds and benzenoid rings on the carbon cages. The interplay between the endohedral YCN cluster and the exhohedral CF3 addends was unveiled according to single-crystal X-ray diffraction studies, thus offering new insight into the chemical reactivity of CYCFs.