A twist on the reaction of the CN radical with methylamine in the interstellar medium: new hints from a state-of-the-art quantum-chemical study

Abstract

Despite the fact that the majority of current models assume that interstellar complex organic molecules (iCOMs) are formed on dust–grain surfaces, there is some evidence that neutral gas-phase reactions play an important role. In this paper, we investigate the reaction occurring in the gas phase between methylamine (CH3NH2) and the cyano (CN) radical, for which only fragmentary and/or inaccurate results have been reported to date. This case study allows us to point out the pivotal importance of employing quantum-chemical calculations at the state of the art. Since the two major products of the CH3NH2 + CN reaction, namely the CH3NH and CH2NH2 radicals, have not been spectroscopically characterized yet, some effort has been made for filling this gap.

The Role of State-of-the-Art Quantum-Chemical Calculations in Astrochemistry: Formation Route and Spectroscopy of Ethanimine as a Paradigmatic Case

“…Since the double-hybrid B2PLYP functional [ 55 ] represents a good compromise between accuracy and computational cost for both structural and spectroscopic properties [ 56 , 57 , 58 ] and is able to provide a reliable description of reactive and non-reactive PESs [ 34 , 35 , 56 , 57 , 59 , 60 , 61 , 62 ], our strategy relies on it in order to provide the final description of the stationary points from a structural point of view. For this purpose, B2PLYP is usually employed in conjunction with a triple-zeta basis sets incorporating diffuse functions.…”

Isocyanoacetylene and cyanoacetylene formation study from C2H2 + CN reaction

“…These values are about 19.9–20.3 $$\rm kJ\,mol^{-1}$$ above other values found in the literature 3,12 . This amount of energy can be partially explained by the basis set the choice of the basis set and the respective level of calculation theory 22 . In Ref.…”

High-Level Rovibrational Calculations on Ketenimine

“…Adding the corrections due to vibrational averaging and Coriolis-coupling results in A 0 = 201.290 38 GHz (−0.08%), B 0 = 9.666 61 GHz (+0.04%), and C 0 = 9.464 40 GHz (+0.04%), where deviations with respect to the experimental results of Rodler et al (1984Rodler et al ( , 1986 are given in parentheses. The agreement of these corrected results with the experimental ones is excellent, but it is well-known that core correlation effects should not be considered without the inclusion of high-level coupled-cluster terms, e.g., CCSDT(Q), at the same time, because they often partly compensate each other (Ruden et al, 2004;Meier et al, 2011;Puzzarini et al, 2020). Moreover, rovibrational intensities as considered below depend on several quantities and the impact of these additional corrections might be different for the individual quantities.…”