Ultraviolet spectrum of periodate ion, IO –4

Abstract

The ultraviolet spectrum of the periodate ion IO^–₄ in several solvents has been resolved into two overlapping gaussian bands, one close to 222 nm (ε_max= 1.0 × 10³ m² mol^–1) and the other close to 280 nm (ε_max= 27 m² mol^–1). Both bands undergo small blue shifts in more polar solvents and it is concluded that they are due to π^*→π^* and n→π^* transitions, respectively. The shift in going from acetonitrile to water is negligible, confirming that hydrogen bonding of the ion to water is weak. The diffuse reflectance spectra of solid NaIO₄ and KIO₄ show bands at ≈ 215, 290, and 330 nm.