Raman spectroscopic studies and DFT calculations on tribromoacetic acid and tribromoacetic acid-d

The Raman spectra of crystalline tribromoacetic acid (CBr3COOH), its deuterated analog (CBr3COOD) and a partially deuterated acid (CBr3COOD/H) have been measured using Raman spectroscopy. Density functional theory (DFT) calculations have been carried out in order to compare the measured spectra with the calculated ones and the bands have been assigned. The theoretical frequencies are close to the ones of the cyclic dimer in the crystal and this fact implies the "oriented gas" model for this compound. The three Raman active intermonomeric modes have been assigned. An extremely weak and broad (similar to 500 cm(-1)) nu OH band for (CBr3COOH)(2) centred at similar to 3000 cm(-1) could be detected. In addition, this band shows relatively sharp submaxima, irregularly spaced, assigned to overtones/summation bands of the COOH group. For the deuterated analog, (CBr3COOD)(2) the OD stretching band is centred at similar to 2230 cm(-1) and shows sharp submaxima as well. In the solid state the tribromoacetic acid consists of dimers while in aqueous solutions the tribromoacetic acid is in monomeric form. (C) 2012 Elsevier B.V. All rights reserved.