Raman spectroscopy studies of temperature induced phase transitions in [N(CH3)3H]CdCl3 and DFT (B3LYP) calculations

[N(CH3)3H]CdCl3 between 295 and 433 K possesses four phases. Three phase transition at T1=416 K, T2=373 K and T3=330 K (on heating) and T1=410 K, T2=386 K and T3=322 K (on cooling) was determined by differential scanning calorimetry. Thermal hysteresis of these transitions ∆T1=6 K, ∆T2=13 K and ∆T3=8 K, indicating a first order character. The X-ray diffraction study at room temperature revealed an orthorhombic system with Pbnm space group. The vibrational characteristics have been measured at room temperature by infrared spectroscopy (400-3800 cm−1) and by polarized Raman spectroscopy (10-3800 cm−1) on microcrystals orientated with respect to the organic and inorganic sublattice. The structure of this compound was optimized by density functional theory (DFT) using B3LYP with LanL2DZ and LanL2MB basis sets. The temperature dependence of the Raman line shifts ν and the half-width ∆ν detect the phase transitions (T1, T2 and T3).