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The quaternary intermetallic compound Na8K23Cd12In48 was obtained in high yield after fusion of the elements in stoichiometric proportions in a Nb container followed by slow cooling. The structure was established by means of single-crystal X-ray diffraction techniques (P6/mmm, Z = 1, a = 17.114(3) A, c = 10.442(2) A; R(F), Rw(F) = 2.74%, 3.34% for 532 independent reflections and 55 parameters varied). It is composed of indium icosahedra, indium triangular clusters, and the novel Cd12In6 tubular cluster. The latter, which contains two sodium cations, stuffs a 96-atom polyhedron (fullerane) and is sheathed by 32 alkali cations (20K+ and 12Na+). The clusters are linked together through two-center two-electron bonds within a 3-D anionic network. The poor metal-like resistivity of the compound (ρ293K = 5 × 10-4 Ω cm) is consistent with the open shell band structure determined by extended Huckel methods. The shortage in electrons of the structure, mainly due to the cation packing limitation, is almost solely bo... |
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