Vibrational spectroscopic studies of solid state reactions

Abstract

A vibrational spectroscopy study on the following solid state reactions are presented: The thermal decomposition reactions of (NH4) 2Cr04 to (NH 4) 2Cr207 and ( NH 4) 2Cr2O7 to Cr203, and the photo isomerization of [ Co ( NH3) 5N02 ]CL2 to [ Co ( NH3) 50N0 ]CL2. A literature survey on the above reactions, as well as vibrational node determination and assignment of these to infrared and Raman bands of the reagents, products and intermediates involved, are included. The react ion kinetics of the decom:E;X)s it ion of ( NH4) 2CrO4 and photoisomer i zat ion of [Co(NH3) 5N02]C12 are determined by Raman and infrared methods respectively. Results obtained for the former reaction can be interpreted in terms of either the contracting cylinder or contracting area equations. Kinetics of the photochemical reaction [Co(NH3) 5NO2 ] CL2 hv [Co(NH3) 5N02 ]CL2 are reported for the first time, and it is a first order reaction. In addition these measurements provide direct evidence of structural changes during the course of the different reactions.