Selective Synthesis, Isolation, and Crystallographic Characterization of LaSc2N@Ih-C80

Abstract

The successful preparation and isolation of the mixed-metal endohedral fullerene, LaSc(2)N@I(h)-C(80), and its structural characterization by single-crystal X-ray diffraction are reported. Results from chemically adjusting plasma temperature, energy, and reactivity (CAPTEAR) experiments indicate that a 10 wt % addition of Cu(NO(3))(2)·2.5H(2)O to a mixture of La(2)O(3) and Sc(2)O(3) decreases the amount of C(60) and C(70) found in soot extracts by an order of magnitude. By combining a stoichiometric 2-fold excess of La to Sc atoms in the plasma reactor, an extract containing a greater abundance of LaSc(2)N@I(h)-C(80) relative to Sc(3)N@I(h)-C(80) was obtained. Alternatively, the stir and filter approach (SAFA method) can be used to remove the empty cage fullerenes from a carbon soot sample prepared without using Cu(NO(3))(2)·2.5H(2)O. LaSc(2)N@I(h)-C(80) has been characterized by UV/vis absorption spectroscopy and by single-crystal X-ray diffraction. Ordered crystals with nearly identical orientations of the endohedral relative to the porphyrin have been obtained by cocrystallization of LaSc(2)N@I(h)-C(80) with either Ni(II)(OEP) or H(2)(OEP). The LaSc(2)N unit is planar, although earlier computations suggested that it would be pyramidal.