Absorption Spectra, Optical Activity and Isotopic Exchange

Abstract

WE have made a systematic examination¹ of the absorption spectra of cobaltammines which undergo isotopic exchange of hydrogen atoms in constituent NH₃ or NH₂ radicals, and more especially of those which are mixtures of optical isomers. Cobaltammines almost invariably give rise to two broad absorption bands² in the visible (I) and near ultraviolet (II) spectrum. Substitution of ²H for ¹H produces an effect upon band (I) illustrated in Fig. 1; it is generally more pronounced the larger the number of exchangeable hydrogen atoms in the molecular ion. Absorption band (II) is scarcely affected, but differences occur in the farther ultra-violet. The full line is representative of protium-containing cobaltammines, the broken line of corresponding deuterium compounds.