Abstract
A new Nb6 oxychloride, PbLu3Nb6Cl15O6,
has been synthesized from stoichiometric amounts of PbO, Lu2O3,
Nb2O5, NbCl5 and Nb, heated at 680 °C.
The crystal structure has been determined by single crystal X-ray diffraction (cubic, Pn, a = 13.8327(4) Å, V = 2646.8(1) Å3, Z = 4).
The structure consists of a f.c.c. stacking of discrete edge-capped Nb6Cli6Oi6Cla6 units in which six oxygen and six chlorine atoms are ordered
on the twelve inner positions, while the six apical ones are occupied by six
chlorines. Additional chlorines, which do not belong to the former units,
are bonded to the lutetium atoms to form Lu2Cl2 entities
that occupy 3/4 of the tetrahedral cavities of the stacking units, while
the lead ions are randomly distributed in the 1/4 remaining tetrahedral
and in the octahedral cavities. The Nb6Cl12O6
units are connected to each other by both the Lu2Cl2
entities and the lead ions to form a three-dimensional framework. This compound
exhibits 14 valence electrons per cluster.