Octahedral Niobium Thiocyanato Complexes Containing [Nb6Cl9O3] Cluster Core: Syntheses, Crystal Structures and Evidences of NCS Ligand Exchange

Abstract

J. Cluster Sci., 2009, 20, 213-22

Octahedral clusters with mixed inner ligand environment: Self-assembly, modification and isomerism

“…Large discrepancy between atomic radii of the halide ligands caused a strong distortion of the metal cluster. The apical NCS groups can be substituted by treatment with strong acids [24]. The discovery of the first mixed oxyhalide cluster ScNb 6 Cl 13 O 3 [27] has opened the field of a new class of niobium octahedral clusters in which ordered oxygen/halogen distribution within the {Nb 6 X 18 } unit (L = O, Cl or Br) leads to clusters with greater distortions of the Nb 6 octahedra, possessing valency electron concentration (VEC) from 13 to 16.…”

“…The same pair of isomers was obtained in the reactions with KNCS. The apical ligands in these anions are rather labile and can be substituted with chloride ligands [ 24,41 ]. It turned out that no inner ligand exchange and no redox process occurred in these reactions and consequently the {Nb 6 Cl 9 O 3 } cluster core remains identical in the starting and final compounds.…”