Theoretical Investigation of the Infrared Spectrum of 5-Bromo-2,4-pentadiynenitrile from a CCSD(T)/B3LYP Anharmonic Potential

Abstract

On the grounds of a hybrid CCSD(T)/B3LYP/aug-cc-pVTZ anharmonic potential and the use of a variational and variational-perturbational methods, the IR spectra of 5-bromo-2,4-pentadiynenitrile (BrC₅ N) is revisited in the mid-infrared region up to 4500 cm^-1 . A position and intensity analysis of our theoretical results allow us to assign the fundamental bands together with their combinations and overtones, in the aforementioned range of frequencies. The main objective of this work is to give an "a priori" complete IR spectrum of BrC₅ N, which can be used as a guide for the low-intensity bands in areas not completely studied so far.

Keywords: 5-bromo-2,4-pentadiynenitrile; ab initio calculations; computational chemistry; density functional theory; vibrational spectroscopy.