A matrix isolation and Ab initio study on C2H6…HCN complex: An unusual example of hydrogen bonding

• Published in: Journal of molecular structure Vol. 1231; p. 129910
• Main Authors: Sosulin, Ilya S., Lukianova, Mariia A., Volosatova, Anastasia D., Drabkin, Vladimir D., Kameneva, Svetlana V.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 05.05.2021
• Subjects: Ab initio calculations; Intermolecular complexes; IR spectroscopy; Matrix isolation; Matrix isolation; Intermolecular complexes; Ab initio calculations; IR spectroscopy
• ISSN: 0022-2860; 1872-8014
• DOI: 10.1016/j.molstruc.2021.129910

•C2H6…HCN complex was obtained in solid Ar by deposition of HCN/C2H6/Ar gas mixtures.•MP2/CBS ab initio calculations reveal 3 possible structures of the complex.•Complex with NCH...C hydrogen bond was observed by FTIR matrix isolation spectroscopy.•Experimental complexation-induced IR spectroscopic shifts well coincide with theory. Hydrogen bonding between saturated alkanes and HX (X is an electronegative fragment) represents a unique type of interaction of this kind. In this work we report a first experimental and ab initio study on HCN…C2H6 complex using FTIR matrix isolation spectroscopy and MP2/CBS calculations. According to theoretical results, three forms of HCN…C2H6 are possible: two with C(HCN)…C1(C2H6) and H(HCN)…C2(C2H6); C(HCN)…C1(C2H6) and N(HCN)…C2(C2H6) contacts and hydrogen-bonded H(HCN)…C(C2H6) axial symmetry structure (the interaction energies are 0.85, 0.79 and 0.77 kcal/mol respectively). Nevertheless, only the last structure is stabilized upon experimental conditions. The hydrogen-bonded complex is spectroscopically characterized by blue shifts of HCN bending (+9.4 cm−1) and CH3 rocking (+9.0 and +11.3 cm−1) and red shifts of H−CN stretching (−24.9 and −20.1 cm−1) and CH3 symmetry stretching (−4.7 cm-1) vibrations. The experiment with deuterated HCN proves this assignment. The obtained results are in good agreement with the previous rotational spectroscopy study.