Spectroscopic and quantum mechanical study of a scavenger molecule: N,N-diethylhydroxylamine

Giovanna Salvitti; Emanuele Pizzano; Filippo Baroncelli; Sonia Melandri; Luca Evangelisti; Fabrizia Negri; Marcello Coreno; Kevin C Prince; Alessandra Ciavardini; Hanan Sa'adeh; Matteo Pori; Marzia Mazzacurati; Assimo Maris

doi:10.1016/j.saa.2022.121555

Spectroscopic and quantum mechanical study of a scavenger molecule: N,N-diethylhydroxylamine

Spectrochim Acta A Mol Biomol Spectrosc. 2022 Nov 15:281:121555. doi: 10.1016/j.saa.2022.121555. Epub 2022 Jul 2.

Authors

Affiliations

¹ Department of Chemistry "G. Ciamician", University of Bologna, I-40126 Bologna, Italy.
² Department of Chemistry "G. Ciamician", University of Bologna, I-40126 Bologna, Italy; BASF Italia S.p.A., Pontecchio Marconi, I-40037 Bologna, Italy.
³ Department of Chemistry "G. Ciamician", University of Bologna, I-40126 Bologna, Italy; Interdepartmental Centre for Industrial Aerospace Research (CIRI Aerospace), University of Bologna, I-47121 Forlì, Italy; Interdepartmental Centre for Industrial Agrifood Research (CIRI Agrifood), University of Bologna, I-47521 Cesena, Italy.
⁴ Interdepartmental Centre for Industrial Aerospace Research (CIRI Aerospace), University of Bologna, I-47121 Forlì, Italy; Interdepartmental Centre for Industrial Agrifood Research (CIRI Agrifood), University of Bologna, I-47521 Cesena, Italy; Department of Chemistry "G. Ciamician", University of Bologna I-48123 Ravenna, Italy.
⁵ Department of Chemistry "G. Ciamician", University of Bologna, I-40126 Bologna, Italy; INSTM, UdR Bologna, I-40126 Bologna, Italy.
⁶ CNR-ISM, Trieste LD2 Unit, I-34149 Basovizza, Trieste, Italy.
⁷ Elettra-Sincrotrone Trieste, in Area Science Park, I-34149 Basovizza, Trieste, Italy; Department of Chemistry and Biotechnology, School of Science, Computing and Engineering Technology, Swinburne University of Technology, Hawthorn, Victoria, Australia.
⁸ CNR-ISM, Trieste LD2 Unit, I-34149 Basovizza, Trieste, Italy; Elettra-Sincrotrone Trieste, in Area Science Park, I-34149 Basovizza, Trieste, Italy; Laboratory of Quantum Optics, University of Nova Gorica, Sl-5001 Nova Gorica, Slovenia.
⁹ Elettra-Sincrotrone Trieste, in Area Science Park, I-34149 Basovizza, Trieste, Italy; Department of Physics, The University of Jordan, JO-11942 Amman, Jordan.
¹⁰ BASF Italia S.p.A., Pontecchio Marconi, I-40037 Bologna, Italy.
¹¹ Department of Chemistry "G. Ciamician", University of Bologna, I-40126 Bologna, Italy; Interdepartmental Centre for Industrial Aerospace Research (CIRI Aerospace), University of Bologna, I-47121 Forlì, Italy. Electronic address: assimo.maris@unibo.it.

PMID: 35926273
DOI: 10.1016/j.saa.2022.121555

Abstract

We report a combination of quantum mechanical calculations and a range of spectroscopic measurements in the gas phase of N,N-diethylhydroxylamine, an important scavenger compound. Three conformers were observed by pulsed jet Fourier transform microwave spectroscopy in the 6.5-18.5 GHz frequency range. They are characterized by the hydroxyl hydrogen atom being in trans orientation with respect to the bisector of the CNC angle while the side alkyl chains can be both trans (global minimum, C_s symmetry, A = 7608.1078(4), B = 2020.2988(2) and C = 1760.5423(2) MHz) or one trans and the other gauche (second energy minimum, A = 5302.896(1), B = 2395.9822(4) and C = 1804.8567(3) MHz) or gauche' (third energy minimum, A = 5960.8025(6), B = 2273.6627(4) and C = 1975.8074(4) MHz). For the global minimum, the ¹³C_α,¹³C_β and ¹⁵N isotopologues were observed in natural abundance, allowing for an accurate partial structure determination. Moreover, several lines were detected by free jet absorption millimeter wave spectroscopy in the 59.6-74.4 GHz spectral range. The electron binding energies of the highest occupied molecular orbital and the next-to-highest occupied molecular orbital, determined by photoelectron spectroscopy, are 8.95 and 10.76 eV, respectively. Supporting calculations evidence that, (i) upon ionization of the HOMO, the molecular structure changes from an amine to an N-oxoammonium arrangement and (ii) the 0-0 of the HOMO-1 photoionization is 10.46 eV. The K-shell binding energies, determined by X-ray photoelectron spectroscopy, are 290.42 eV (C_β), 291.45 eV (C_α), 405.98 eV (N) and 538.75 eV (O). The Fourier transform near infrared spectrum is reported and a tentative assignment is proposed. The equilibrium wavenumber (ω̃ = 3811 cm^-1) and the anharmonicity constant (ω̃χ = -87.5 cm^-1) of the hydroxyl stretching mode were estimated using a quadratic model.

Keywords: NO compounds; Near infrared spectroscopy; Photoelectron spectroscopy; Quantum mechanical modeling; Rotational spectroscopy.

MeSH terms

Electrons*
Hydroxylamines
Molecular Structure
Photoelectron Spectroscopy
Quantum Theory*

Substances

Hydroxylamines
N,N-diethylhydroxylamine