Schwingungsspektren und Normalkoordinatenanalysen der 92Mo-, 100Mo-, 35Cl- und 37Cl-Isotopomeren der Clusteranionen [(Mo6X)Y]2−; Xi = Cl,Br; Ya = F,Cl, Br,I |
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Authors: | D Bublitz W Preetz |
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Abstract: | Vibrational Spectra and Normal Coordinate Analysis of 92Mo, 100Mo, 35Cl, and 37Cl Isotopomers of the Cluster Anions (Mo6X )Y ]2?; Xi = Cl, Br; Ya = F, Cl, Br, I The tetrabutylammonium (TBA) salts of the octa-μ3-halogeno-hexahalogeno-octahedro-hexamolybdate(2 –) anions (Mo6X )Y ]2?; Xi = Cl, Br; Ya = F, Cl, Br, I; have been synthesized using 92Mo, 100Mo, 35Cl, and 37Cl. The 10 K IR and Raman spectra reveal significant frequency shifts due to the isotopic labelling of the Mo6 cage, the inner sphere halides X8i or the outer sphere ligands Y , respectively. The normal coordinate analysis yields (Mo? Mo) valence force constants of about 1.3 to 1.5 mdyn/Å. For the μ3-bonded halogenes Cli and Bri valence force constants of 1.1 resp. 1.0 mdyn/Å are calculated. The values for (Mo? Ya) bonds are found in the usual halide range. The observed isotopic shifts are verified very well by the calculations, allowing detailed assignment of the IR and Raman spectra of these compounds for the first time. |
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Keywords: | Octa-μ 3-halogeno-hexahalogeno-octahedro-hexamolybdate(2 – ) anions Isotopomers Raman IR Spectra Normal Coordinate Analysis Force Constants |
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