Vibrational Spectroscopic Studies and Computational Study of

FT-IR and FT-Raman spectra of 1,2-diphenyl-4-n-Butyl-3,5-pyrazolidinedione (Phenylbutazone) were recorded and analyzed. The vibrational wavenumbers were computed using HF/6-31G(d) and B3LYP/6-31G(d) basis sets and compared with experimental data. The first hyperpolarizability, infrared intensities and Raman activities are also reported. The geometrical parameters of the title compound obtained from theoretical calculations are in agreement with that of reported similar derivatives. The first hyperpolarizability is comparable with reported values of similar derivatives and is an attractive molecule for future applications in non-linear optics. The variation in C-N bond lengths suggests an extended π-electron delocalization over the pyrazolidinedione moiety which is responsible for the nonlinearity of the molecule