Infrared spectra of CH₂Cl₂, CH₂Br₂, and CH₂ I₂: in the solid state

Abstract

The infrared spectra of CH₂Cl₂, CH₂Br₂, and CH₂I₂ in the solid state at liquid nitrogen temperatures are presented. These spectral data indicate an orthorhombic structure with four molecules per unit cell for CH₂Cl₂ and a triclinic or monoclinic structure for CH₂Br₂. For CH₂I₂ the data show that the molecule in the solid state possesses a C₂ site symmetry and that there should be more than one molecule per unit cell. It is shown that the infrared spectrum of solid CH₂I₂ obtained here is different from that reported for forms I and II by earlier workers, and indicates the existence of a third form.