Thermal and magnetic properties and vibrational analysis of 4-(dimethylamino) pyridine: a quantum chemical approach.

The FT-IR and FT-Raman spectra of 4-(dimethylamino) pyridine (4DMAP) have been recorded in the region 4000-500 cm(-1)and 3500-100 cm(-1). Quantum chemical calculations of energy, geometry and vibrational wavenumbers of 4DMAP were carried out by using ab initio HF and density functional theory (DFT/B3LYP) with complete relaxation in the potential energy surface using 6-311++G(d,p) basis set. The harmonic vibrational wavenumbers were calculated and the scaled wavenumbers have been compared with the experimental FT-IR and FT-Raman spectra. The quantum chemical parameters have been computed from the HOMO-LUMO energy values. Temperature dependence thermodynamic parameters and magnetic properties of the title compound have been analyzed. Using NBO analysis the stability of the molecule arising from hyper-conjugative interactions, charge delocalization has been analyzed. The first-order hyper-polarizability (β) values of the title molecule were computed by B3LYP method. Finally the theoretically spectrograms for FT-IR and FT-Raman spectra of the title molecule have been constructed which show good agreement with recorded spectra. Crown