Electronic Absorption Spectra of Square-Planar <i>d</i>8 Complexes in Different Crystal Environments

Abstract

Polarized crystal spectra of K2PdCl4 and K2PtCl4 have been measured at room temperature and interpreted by means of a vibronic intensity-borrowing mechanism. Single-crystal spectra of Magnus's green salt, Pt(NH3)4PtCl4, and its methylamine analog have also been measured, together with the powder spectra of a wide range of related salts. The visible absorptions are assigned to d—d transitions within axially perturbed anions, while a new infrared band in Magnus's green salt is identified with an intermolecular electron-transfer transition.