Metallic nitride fullerenes (MNFs) and oxometallic fullerenes (OMFs) react quickly with an array of Lewis acids. Empty-cage fullerenes are largely unreactive under conditions used in this study. The reactivity order is Sc4O2@I-h-C-80 > Sc3N@C-78 > Sc3N@C-68 > Sc3N@D-5h-C-80 > Sc3N@I-h-C-80. Manipulations of Lewis acids, molar ratios, and kinetic differences within the family of OMF and MNF metallofullerenes are demonstrated in a selective precipitation scheme, which can be used either alone for purifying Sc3N@I-h-C-80 or combined with a final high-performance liquid chromatography pass for Sc4O2@I-h-C-80, Sc3N@D-5h-C-80, Sc3N@C-68, or Sc3N@C-78. The purification process is scalable. Analysis of the experimental rate constants versus electrochemical band gap explains the order of reactivity among the OMFs and MNFs.