Matrix isolation FTIR and ab initio study of complexes between formic acid and nitrogen Original Research Article

The structure, energetics, and infrared spectra of nitrogen complexes of formic acid and its deuterated analogs have been investigated. Both FTIR matrix isolation technique and ab initio molecular orbital calculations have been employed. Two minima on the complex potential energy surface were found. One complex minimum resembles an almost linear hydrogen bond and the other minimum is directed to the hydroxyl oxygen lone electron pairs. The calculations and experimental results indicate substantial perturbations in the fundamental vibrational modes upon the complexation. Good agreement between the observed and the calculated complexation shifts on the vibrational fundamentals of the most stable species is obtained. Mostly affected are the modes connected with the complexation sites, e.g. the O-H stretching and torsional modes. The observed complex band structures and locations display the shape of the potential responsible for the 1:1 interaction.