The interplay and strength of the pi center dot center dot center dot H-F, C center dot center dot center dot H-F, F center dot center dot center dot H-F and F center dot center dot center dot H-C hydrogen bonds upon the formation of multimolecular complexes based on C2H2 center dot center dot center dot HF and C2H4 center dot center dot center dot HF small dimers

摘要

The conception of this theoretical research was idealized aiming to unveil the intermolecular structures of complexes formed by acetylene or ethylene and hydrofluoric acid. At light of computational calculations by using the B3LYP/6-311++ G(d, p) method, the geometries of the C2H2 center dot center dot center dot(HF), C2H2 center dot center dot center dot 2(HF), C2H2 center dot center dot center dot 4(HF), C2H4 center dot center dot center dot(HF), C2H4 center dot center dot center dot 2(HF) and C2H4 center dot center dot center dot 4(HF) hydrogen-bonded complexes were fully optimized. Moreover, the Post-Hartree-Fock calculations MP2/6-311++ G(d, p), MP2/aug-cc-pVTZ, MP4(SDQ)/6-311++ G(d, p) and CCSD/6-311++ G (d, p) also were also used. The infrared spectra were analyzed in order to identify the new vibrational modes and frequencies of the proton donors shifted to red region. Through the modeling of charge-fluxes on the basis of the Quantum Theory of Atoms In Molecules (QTAIM) and, by contradicting the expectation of the hydrofluorination mechanisms of acetylene or ethylene, C center dot center dot center dot H-F was recognized as a new type of hydrogen bond instead of the alreadywell known pi center dot center dot center dot H. The calculations of the Natural Bonding Orbital (NBO) and Charges derived fromthe Electrostatic Potential Grid-based (ChElPG) were also applied to interpret the shifting frequencies as well as measuring of the punctual charge-transfer after the formation of the complexes. Finally, the determination of the stabilization energy was carried out through the arguments of the Fockmatrix in NBO basis and through the supermolecule approach. Also it is worthwhile to notice that some algebraic formulationswere used for determining the electronic cooperative effect (CE). (C) 2019 Elsevier B.V. All rights reserved.