Far-infra-red Spectra of some Square-planar Ions

Abstract

THERE are three different assignments of the infra-red-active modes of K₂PtCl₄ in the literature^1–3. One was based on a low-resolution spectrum¹ and is thus misleading. The other two authors differed in their assignment of ν₂ and ν₇, but their data are in good agreement except that Mathieu et al.³ reported a band at 160 cm⁻¹ which was not found by either Sacconi et al.² or by ourselves. We have observed the spectrum of K₂PtCl₄ to 40 cm⁻¹ and support Sacconi's results and assignment for the following reasons.