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 Bun 4NCdI3, 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.