Spectroscopic studies of sulfite-based polyoxometalates at high temperature and high pressure

Structural changes occurring within non-conventional Dawson-type [alpha/beta-Mo18O54(SO3)(2)](4-) polyanions in the form of tetrapentylammonium salts were studied by a combination of IR. Raman and visible spectroscopy at high temperature and high pressure. Evidence of the formation of bronze-type materials above 400 K and also upon pressurization to 8 GPa is presented. This conclusion is suggested to be a general result for polyoxometalate compounds subjected to extreme conditions and it opens opportunities for the design of new materials with interesting optical and electronic properties. (C) 2011 Elsevier Inc. All rights reserved.