Journal of the American Chemical Society, Vol.121, No.29, 6827-6833, 1999
Ti2Nb6O12, a novel niobium oxide cluster compound with "Chevrel phase" intercluster connectivity type
The niobium oxide cluster compound Ti2Nb6O12 was synthesized from NbO, NbO2 and TiO2 in the presence of NaF melt at 950 degrees C. It crystallizes in an original structure type based on octahedral cluster units (Nb6O12i)O-6(a). The clusters connect to each other through outer-inner linkages to form a three-dimensional framework containing cubeoctahedral cavities. The cluster connectivity pattern in Ti2Nb6O12 and intercluster metal-metal distances are similar to those found in the "Chevrel phases". The Ti4+ ions have a distorted octahedral environment formed by the oxide ligands belonging to the clusters. Band structure calculations indicate that the lowest unoccupied band in Ti2Nb6O12 resembles the conduction band in the superconducting "Chevrel phases".