A theoretical study on the molecular structure and vibrational (FT-IR and Raman) spectra of a new organic-inorganic compound of 2[N(C3H7)4]SbCl4

The salt bis-tetrapropylammonium tetrachloroantimonate (III) is crystallized in the monoclinic system with the P21/c space group. The unit cell dimensions are: a = 18.1973(5) Å, b = 15.7225(4) Å, c = 13.6491(3) Å, β = 91.65(1)° and Z = 4. The vibrational spectra have been measured at room temperature by FT-infrared spectroscopy (4000-400 cm−1) on polycrystalline samples, and by FT-Raman spectroscopy (3500-30 cm−1) on monocrystals. The structure of the 2[N(C3H7)4]SbCl4 formed by two types of cations (C3H7)4N+ and two types of anions [SbCl4]− was optimized by density functional theory (DFT) using the B3LYP method. Actually the values obtained by the B3LYP/LanL2MB basis with the aid of a calculation of the potential energy distribution (PED) are in good agreement with the experimental data. A root mean square (rms) difference value was calculated and the small differences between experimental and calculated modes have been interpreted by intermolecular interactions with-in the crystal. A comparison between the results of the 2[N(C3H7)4]SbCl4 compound and the simulated compounds based on the (CH3)4N+) and (C2H5)4N+ fragments, shows an increase in the wavenumber of the bands assigned to the stretching vibration of the (NC) group for the 2[N(C3H7)4]SbCl4 compound. The comparison between the [N(C3H7)4]Cl ligand and the 2[N(C3H7)4]SbCl4 compound of the infrared and Raman spectrum shows an increase in the wavenumber for the bands assigned to the stretching vibration of (CH3) and the bending vibration of (NC4) groups in the 2[N(C3H7)4]SbCl4 compound.