On the interaction of propynal with HNO, HF, HCl, H2O, CH3OH, and NH3: Red- and blue-shifting hydrogen bonds and tetrel bonds

Publication date: Available online 22 May 2019Source: Computational and Theoretical ChemistryAuthor(s): Alfred KarpfenAbstractThe potential energy surfaces of the complexes of propynal, (propiolaldehyde, propargyl aldehyde, HCCCOH), with a series of small molecules (HNO, HF, HCl, H2O, CH3OH, and NH3) have been investigated theoretically at the MP2 and CCSD(T) levels using several extended basis sets. Thirty low-lying minima have been detected, eight for HCCCOH-HNO, four for each of the dimers HCCCOH-HF, HCCCOH-HCl, and HCCCOH-H2O, seven for the HCCCOH-CH3OH complex, and three for HCCCOH-NH3. The most stable HCCCOH-HNO complex has a non-planar, orthogonal structure with a tetrel bond and a hydrogen bond. In most cases the calculated intramolecular bond length changes as induced by complex formation are allegeable on the basis of the intramolecular harmonic force fields of propynal and the partner molecules. The vibrational frequency shifts, typical for formyl groups engaged in hydrogen bonding, red shifts of C=O stretches and blue shifts of C-H stretches, occur in most of the dimers, whereas the acetylenic C-H and C≡C stretches are red-shifted when this C-H bond is involved in hydrogen bonding. In almost all HCCCOH-HNO complexes, the N–H stretching frequency is also blue-shifted. However, in case of the most stable HCCCOH-HNO complex a red-shift of the harmonic N-H stretch is calculated. Inclusion of anharmonic contributions reduces this red shift substantially and even co...

Source: Computational and Theoretical Chemistry - May 24, 2019 Category: Chemistry Source Type: research