Infrared and Raman spectra and the vibrational assignment of hexamethylenetetramine‐h₁₂ and ‐d₁₂

The infrared spectra of polycrystalline hexamethylenetetramine‐h₁₂ and ‐d₁₂ (HMT‐h₁₂ and HMT‐d₁₂) at 300 and 100°K, and the Raman spectra of polycrystals, single crystals, and saturated aqueous solutions of HMT‐h₁₂ and HMT‐d₁₂ at 300°K, have been recorded. The infrared spectra and the Raman spectra of the single crystals yielded an unambiguous assignment of most of the zero wave vector fundamental vibrations in the solid. Product rule and normal coordinate calculations verified the mutual compatibility of the assignments for the two isotopic molecules, and gave a detailed description of the vibrational modes. The spectra of HMT‐h₁₂ and their assignment differ slightly from those of previous authors, while the spectra of HMT‐d₁₂ have not been reported previously. The only F₁ mode whose frequency is well established is ν₁₆, at 378 cm⁻¹ in HMT‐h₁₂ and 315 cm⁻¹ in HMT‐d₁₂. The longitudinal and transverse components of several of the infrared‐active F₂ modes have been unambiguously assigned in the Raman spectra.