Formation enthalpies and dipole moments of the complexes of some tertiary phosphines with trifluoroacetic acid

Kinetic Energy Density as a Predictor of Hydrogen-Bonded OH-Stretching Frequencies

“…The extensive literature on the hydrogen bond has enabled investigations of how it is affected when small and/or large perturbations are performed, for example, changing the hydrogen bond acceptor atom along the periods or down the groups in the periodic table. Much work has been done to try to understand how the strength of a hydrogen bond correlates with physical parameters, including various structural and spectroscopic properties, most commonly in solid or liquid phases. − In the present work, we consider OH–Y (where Y  N, O, P, S) hydrogen bonds, which have been the focus of a number of gas-phase room-temperature vibrational spectroscopy studies by some of the authors over the past decade. − The OH–N hydrogen bond, the strongest of the four, was first detected in the 1960s in the gas phase at room temperature, with large OH-stretching red shifts of ∼300 cm –1 for the complexes between methanol (MeOH) and dimethylamine (DMA)/trimethylamine (TMA). ,, In contrast, the OH–O, OH–P, and OH–S hydrogen bonds are similar and exhibit more modest OH-stretching red shifts of 103–140 cm –1 . − , Consequently, fewer investigations of these hydrogen bonds exist compared to those of the OH–N hydrogen bond, and at room temperature in the gas phase only limited studies are available. ,− …”

“…[10][11][12][13]15 Consequently, fewer investigations of these hydrogen bonds exist compared to those of the OH-N hydrogen bond, and at room temperature in the gas phase only limited studies are available. 10,[16][17][18][19][20][21][22][23][24][25][26][27] In the present work, we consider three examples of OH-N hydrogen bonds in complexes that involve pyridine, which is a weaker N based acceptor molecule than DMA or TMA. It is expected that this will result in OH-N hydrogen bonds of intermediate strength, complementing the existing literature for strong OH-N hydrogen bonds, 9,14,28 and for the weaker OH-O, OH-P and OH-S hydrogen bonds.…”