Vibrational Spectra and Molecular Potential Fields of Mercurous Chloride, Bromide, and Iodide

The Raman and infrared spectra of solid mercurous chloride, bromide, and iodide have been recorded and the vibrational fundamentals assigned on the basis of $D_{\mathrm{\infty h}}$ molecular symmetry. Normal modes were found at 279, 250, 169, 107, and 42 cm⁻¹ for the chloride, 220, 184, 136, 71, and 37 cm⁻¹ for the bromide, and at 194, 138, 113, 49, and 31 cm⁻¹ for the iodide. The potential fields of the molecules have been analyzed assuming the most general valence forces. The potential constants and normal modes are described and discussed in terms of the assignments. The mixing of the Hg–Hg and the Hg–X stretching modes is considered in detail.