How CO2 Interacts with Carboxylic Acids: A Rotational Study of Formic Acid-CO2

Annalisa Vigorito; Qian Gou; Camilla Calabrese; Sonia Melandri; Assimo Maris; Walther Caminati

doi:10.1002/cphc.201500531

How CO2 Interacts with Carboxylic Acids: A Rotational Study of Formic Acid-CO2

Chemphyschem. 2015 Oct 5;16(14):2961-7. doi: 10.1002/cphc.201500531.

Authors

Annalisa Vigorito¹, Qian Gou^{1

2}, Camilla Calabrese¹, Sonia Melandri¹, Assimo Maris³, Walther Caminati¹

Affiliations

¹ Dipartimento di Chimica "Giacomo Ciamician", dell'Università degli Studi di Bologna, via Selmi 2, I-40126 Bologna (Italy).
² Current address: School of Chemistry and Chemical Engineering, Chongqing University, Chongqing, 400030 (P. R. China).
³ Dipartimento di Chimica "Giacomo Ciamician", dell'Università degli Studi di Bologna, via Selmi 2, I-40126 Bologna (Italy). assimo.maris@unibo.it.

PMID: 26247850
DOI: 10.1002/cphc.201500531

Abstract

The rotational spectra of the 1:1 formic acid-carbon dioxide molecular complex and of its monodeuterated isotopologues are analysed in the 6.5-18.5 and 59.6-74.4 GHz frequency ranges using a pulsed jet Fourier transform microwave spectrometer and a free-jet absorption millimetre wave spectrometer, respectively. Precise values of the rotational and quartic centrifugal distortion constants are obtained from the measured frequencies, and quadrupole coupling constants are determined from the deuterium hyperfine splittings. Structural parameters are estimated from the moments of inertia and their differences among isotopologues: the complex has a planar structure with the two subunits held together by a HC(O)OH⋅⋅⋅O=C=O (2.075 Å) and a HC(OH)O⋅⋅⋅CO2 (2.877 Å) interactions. The ab initio intermolecular binding energy, obtained at the counterpoise corrected MP2/aug-cc-pVTZ level of calculation, is De =17 kJ mol(-1).

Keywords: ab initio calculations; carbon dioxide; formic acid; hetero dimers; microwave spectroscopy.