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Keywords:

  • EXAFS spectroscopy;
  • Cluster compounds;
  • Polyanions;
  • Solid-state structures;
  • Ab initio calculations

Abstract

The nonastannide clusters have been investigated usingEXAFS, NMR and Raman spectroscopy as well as quantum chemical calculations explicitly considering a model cationic field and solid-state statistics. NMR spectroscopic andEXAFS results are basically identical to those previously published and consistent with a fluctional model of the cluster. The quantum chemical calculations show that there is no significant difference in energy between the two model geometries, C4v and D3h, and that the vibrational frequencies are very low, clearly indicating that the cluster is expected to be fluctional. The solid-state statistics show that both model geometries can be used to describe all known nonastannide structures with reasonable success, illustrating that the classification of the nonastannide clusters in terms of specific symmetries is entirely arbitrary. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)