The molecular structure and properties of 5-(dimethylphenylammonium)-valeric acid bromide hydrate have been characterized by X-ray diffraction, B3LYP/6–311++G(d,p) calculations, FTIR and Raman spectra. The molecules are linked through the water molecules into centrosymmetric dimers arranged into a layered strongly anisotropic structure. It has been found that the bromide anion interacts with water molecule. The FTIR spectrum shows a broad absorption in the 3300–2200 cm −1 region attributed to the ν COOH⋯OH 2 and ν Br − ⋯H 2 O. A comparison was made between the conformation of valeric acid unit in hydrate and anhydrous forms in the isolated molecules and in the crystal. The experimental and theoretical infrared spectra are discussed. The potential energy distributions (PED) have been used to assign the bands in vibrational spectrum.
