Études des spectres infrarouges de polymolybdates et polywolframates alcalins anhydres entre 4000 et 200 cm−1

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Résumé

On a déterminé les spectres infrarouges, entre 4000 et 200 cm−1, de polymolybdates et polywolframates alcalins, MmM'nOx (M = alcalin, M' = Mo ou W). On propose une interprétation des spectres observés, en accord avec une structure construite d'octaèdres M'O6 déformés et de tétraèdres irréguliers M'O4, joints par les sommets. On trouve, en outre, une isotypie entre les tétramolybdates de K, Rb et Cs, et, d'un autre côté, entre les triwolframates de Rb et Cs.

Abstract

The infrared spectra of alkaline polymolybdates and polytungstates, MmM'nOx (M = alkali metal, M' = Mo or W), were determined from 4000 to 200 cm−1. An assignment of the observed bands is proposed in accordance with a structure consisting of deformed M'O6 octahedra and irregular M'O4 tetrahedra joined together at the corners. Furthermore, it was found that K, Rb and Cs tetramolybdates are of the same type, whereas Rb and Cs tritungstates constitute another type.

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