“…As already demonstrated for mononuclear octahedral mixed-fluoro complexes, 19 F NMR spectroscopy is a very specific, sensitive, and high-resolution method for the elucidation of reactions, the structures of the reaction products and the distribution of the individual species within a series (see section II.D). Therefore the application of this technique to the more complicated mixed hexanuclear metal halide clusters was very obvious, because these systems could not be completely analyzed in previous studies. ,,, The respective terminal members of possible series, [(M 6 X i 12 )Y a 4 ] or [(M 6 X i 12 )Y a 6 ] 4- and [(M 6 X i 8 )Y a 4 ] or [(M 6 X i 8 )Y a 6 ] 2- , Y = X or Y ≠ X, have been studied extensively by X-ray structure analyses 372-379 and by electronic and vibrational spectroscopy. , Apart from the condition Y ≠ X, the three cluster units of [(M 6 X i 8 )Y a 6 ] 2- are known from Mo and W (see Figure c) and present three opportunities for systematic variations. Firstly, the outer octahedral coordination sphere Y a 6 can be a mix of two ligands, which results in 10 species, where, preferentially, one of the outer sphere ligands is F to allow for 19 F NMR spectroscopy.…”