FT-IR characterization of Titanium tetrabutoxide catalyst of ethylene dimerization: a DFT Study

Ethylene dimerization is a topic of major fundamental and applied importance. It has triggered much research and scientific effort to improve performance of the catalysts used in the industrial scale. Of the metals studied, titanium-based compounds have been found to be ideally suited, giving high yields of 1-butene. Computational chemistry, and in particular density functional theory (DFT), has been proven to give insights for a better understanding of reaction mechanisms that play a role in homogeneous catalysis. Vibrational spectroscopy is an excellent method for structural analysis and the determination of molecular interactions. In this research, the DFT calculations were done to study optimized structure and theoretical FT-IR spectroscopic data for the titanium tetrabutoxide as a conventional catalyst in the ethylene dimerizaiton. In this regard, firstly the B3LYP/LANL2DZ basis set for Ti atom and B3LYP/6-31G basis set for C, H, and O atoms were used. After optimization, configuration of the titanium tetrabutoxide structure was disrupted. Therefore, optimization method was qualified by the B3LYP/6-31+G (d,p) basis set for all atoms. The results revealed a tetrahedral structure in gas phase with basic parameters of r(Ti...O) 1.81Å and ∠(O—Ti...O) ≈108.39˚. The comparison of theoretical and experimental frequencies of vibrational assignments in the FT-IR spectrum showed that all frequencies computed by the DFT had good agreement with those observed in the experimental results.

DFT, Ethylene dimerization, FT-IR, Tinanium tetrabutoxide