Sc3N@(C-80-I-h(7))(CF3)(14) and Sc3N@(C-80-I-h(7))(CF3)(16). Endohedral Metallofullerene Derivatives with Exohedral Addends on Four and Eight Triple-Hexagon Junctions. Does the Sc3N Cluster Control the Addition Pattern or Vice Versa?
The compounds Sc3N@(C-80-I-h(7))(CF3)(14) and Sc3N@(C-80-I-h(7))(CF3)(16) (2) were prepared by heating Sc3N@C-80-I-h(7) and Ag(CF3CO2) to 350 degrees C in a sealed tube. The structures of 1 and 2 were determined by single-crystal X-ray diffraction. They are the first X-ray structures of any endohedral metallofullerene with more than four cage C(sp(3)) atoms. The structures exhibit several unprecedented features for metallic nitride fullerenes, including multiple cage sp(3) triple-hexagon junctions (four on 1 and eight on 2), no cage disorder and little (2) or no (1) endohedral atom disorder, high-precision (C-C esd's are 0.005 angstrom for 1 and 0.002 angstrom for 2), an isolated aromatic C(sp(2))(6) hexagon on 2, and two negatively charged isolated aromatic C(Sp(2))(5)(-) pentagons on 2 that are bonded to one of the Sc atoms. DFT calculations are in excellent agreement with the two Sc3N conformations observed for 2 (Delta E(calc) = 0.36 kJ mol(-1); Delta E(exp) = 0.26(2) kJ mol(-1)).