Theoretical force-field model for blue-shifted hydrogen bonds with fluoromethanes

Disorder of Hydrofluorocarbon Molecules Entrapped in the Water Cages of Structure I Clathrate Hydrate

“…Therefore, the blueshift of the guest molecule is a sign of hydrogen bonding between the host water and hydrogen of the guest (C−H⋅⋅⋅O). Theoretical calculations suggest the occurrence of blueshifted hydrogen bonds between hydrogen of the HFCs and H 2 O, but other theoretical calculations and structural and energetic analyses suggest that the fluorine atoms in the HFCs may act as hydrogen‐bond acceptors in a complex with water, although neither of these theoretical models are for guests in clathrate hydrate . These two possibilities probably contribute to large guest molecules being too large to fit into the 5 12 cages.…”

The dimers of glyoxal and acrolein with H2O and HF: Negative intramolecular coupling and blue-shifted C–H stretch

“…The NIC between adjacent bonds is linked to positivity of the corresponding off-diagonal harmonic coupling force constant. This has recently been shown for halomethanes [16] and for a series of triatomics [18]. From harmonic normal coordinate analysis, we calculate this term f C1-H1/C1@O1 as equal to 0.45 and 0.53 mdyn/Å for Gly and Acr, respectively.…”

“…Depending on the sign of the intramolecular coupling between X-H and R-X bonds, the m(X-H) stretch appears either red-or blue-shifted. If this coupling is negative -a case of a 'negative intramolecular response' (NIR) -the blue shift of the m(X-H) stretch may be observed [12][13][14][15][16][17][18][19][20][21]. Therefore, the presence of negative intramolecular coupling (NIC) of a given molecule is likely to be the precondition of a possible appearance of the blue-shifted m(X-H).…”

“…It determines the shape of an important section of its potential energy surface (PES) and often predetermines the structural response to the interaction partner(s). The class of NIR-type molecules includes halomethanes [12,14,16], formaldehyde and substituted formaldehydes RHCO [13,17], dimethyl ether [15], fluorosilanes [19], fluorophosphines, and fluoroarsines [20], as well as the series of triatomic molecules HNO, HSN, HPO, and HPS [18]. A more extended list of blue-shifted complexes is given in [21].…”

He2@C60: Thoughts of the concept of a molecule and of the concept of a bond in quantum chemistry

“…Writing on the special occasion is always a welcomed and pleasant work as it allows to explore some more unusual ideas, thoughts, and concepts that may not be fully appropriate for the standard mode of scientific paper . Some such speculative notions are perfectly suitable for the Festschrift publication and the authors do not necessarily need to worry of being carried away too far on their, if any, wings of imagination and wings of thoughts.…”