Trigonal-prismatische Nb6-Einheiten in Verbindungen des Typs A3[Nb6SBr17] (A = Tl,K, Cs) |
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Authors: | Hermann Womelsdorf,H.-Jü rgen Meyer |
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Abstract: | Trigonal-prismatic Nb6-Units in Compounds of the Type A3[Nb6SBr17] (A = Tl, K, Cs) The new compounds A3[Nb6SBr17] (A = Tl, K, Cs) were synthesized and their lattice parameters were calculated from indexed X-ray powder patterns. An intensity measurement based on a single-crystal of Tl3[Nb6SBr17] was performed with an automatic four-circle diffractometer (a = 1704.9(1) pm, b = 1862.8(3) pm, c = 932.51(7) pm; β = 90.747(7)°, Vm = 445.9(3) cm3/mol; C2/c, Z = 4). The structure refinement confirmed consistency with the Rb3[Nb6SBr17] structure, found previously. The comparison of both structures yielded no significant differences concerning the distances within the sulfur-centered Nb6S cluster core. Extended Hückel calculations revealed a maximum of the niobium–niobium overlap populations for (the actual present number of) 14 electrons occupying metal–metal bonding states. |
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Keywords: | Tl3[Nb6SBr17] Cs3[Nb6SBr17] K3[Nb6SBr17] synthesis crystal structure electronic structure |
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