Putting a terbium-monometallic cyanide cluster into the C82 fullerene cage: TbCN@C2(5)-C82.

The first terbium (Tb)-monometallic cyanide clusterfullerene (CYCF), TbCN@C82, has been successfully synthesized and isolated, whose molecular structure was determined unambiguously as TbCN@C2(5)-C82 by single crystal X-ray diffraction. The C2(5)-C82 isomeric cage represents a new cage capable of encapsulating a monometallic cyanide cluster. The C-N bond length within the encaged TbCN cluster is determined to be 0.94(5) Å, which is smaller by at least 0.17 Å than those of the reported C-N triplet bonds in traditional cyanide/nitrile compounds and cyano coordination complexes. An electronic configuration of [Tb(3+)(CN)(-)](2+)@[C82](2-) was proposed for TbCN@C82.