Thermal Motion of Ammine Groups in Carbonatotetrammine Cobalt (III) by Proton Nuclear Magnetic Resonance

Abstract

The broad-line NMR spectra of carbonatotetramminecobalt (III) bromide were observed in polycrystalline state at temperatures between 77°K and 383°K. It has been concluded that 1) from 200°K to 383°K the ammine groups are rotating about the Co–N axis, 2) there is no motion of the complex cation as a whole up to the decomposition point, and 3) below 90°K one of the four ammine groups in each complex becomes stationary.