A Hexanuclear Niobium Cluster Compound With Intra-Cluster Chelate Ligands: [Nb6 (OC2 H4 NH2 )12 ]I3.

From the reaction of [Nb6 I11 ] with 2-aminoethanol in pyridine the cluster compound [Nb6 (OC2 H4 NH2 )12 ]I3 has been obtained and the single-crystal X-ray structure determined. It represents the first example of a group VB metal cluster compound with hexanuclear, octahedral metal atom core, which carries intra-cluster chelate ligands. With the formation of this unprecedented cluster cation we report for the first time a transformation of a 6-8 to a 6-12 type cluster unit. The formation of the cluster cation goes along with a one-electron oxidation of the cluster starting material. Furthermore, it adds a second entry to the so far very small group of M6 cluster compounds with organic ligands on the inner cluster sites.