Preparation and characterisation of solid ditetra-alkylammonium tetrahalogenocadmates (R4N)2CdX4(R = Me, Et, or Bun; X = I or Br) and tetra-n-butylammonium tri-iodocadmate Bun4NCdI3, and an interpretation of their vibrational spectra

Abstract

A new and simple method of preparing these salts by mixing hot ethanolic solutions of the components and subsequent precipitation is described. They were characterised by chemical analysis, X-ray powder photographs, and vibrational spectroscopy. The i.r. and Raman spectra indicate that in the tetrahalogenocadmates the cadmium atoms are tetrahedrally co-ordinated to the halogen, and that this co-ordination persists in Buⁿ₄NCdI₃ where the anions appear to be dimeric, i.e., this salt should be formulated as (Buⁿ₄N)₂Cd₂I₆. The vibrational spectrum of solid cadmium iodide is also reported in detail. A limited X-ray structural study showed (Et₄N)₂CdI₄ to be tetragonal with 8 molecules per unit cell.