Solid-State and Solution FT-Raman Spectra of the Tetraiodine Dication I₄²⁺

Abstract

I₄ ²⁺ is the only known cyclic homopolyatomic cation or anion of iodine. It has a rectangular planar structure which may be thought of as containing two I₂ ⁺ units joined by a weak π∗-π∗ 4 centre 2 electron bond.¹ In this paper we report our FT-Raman spectra of I₄ ²⁺, which conflict with those published by Gillespie et al. ¹ and present evidence that the peaks attributed to a species containing iodine in the +1 oxidation state are in fact due to I₄ ²⁺.