Room Temperature Gibbs Energies of Hydrogen-Bonded Alcohol Dimethylselenide Complexes

Abstract

A number of hydrogen-bonded complexes, formed between an alcohol donor and dimethylselenide, have been detected experimentally, at room temperature in the gas phase using FTIR spectroscopy. The Gibbs energy of complex formation has been determined from the measured integrated absorbance of the hydrogen-bonded OH stretching band and the calculated oscillator strength of the associated transition. The OH stretching frequency and Gibbs energy of the selenium hydrogen-bonded complexes are compared to those found in complexes with the same donor molecule and either dimethylether (O) or dimethylsulfide (S) as the acceptor molecule. For a given donor, we found a similar OH stretching frequency in the complexes for each of the three acceptors O, S, and Se. However, the Gibbs energies were found to be less positive (i.e., stronger bound) for the dimethylether complexes (OH•O), as compared to the dimethylsulfide (OH•S) and dimethylselenide (OH•Se) complexes, with the latter two having comparable Gibbs energies.

Lactic Acid Spectroscopy: Intra- and Intermolecular Interactions

“…56 It is possible to calculate the kinetic energy density evaluated within an isovolume with the boundary condition set to s(r) = 0.5, and this has been shown to be a good measure of the strength of the hydrogen-bonding interaction. 13,18,19,25,26 The kinetic energy density of a hydrogen bond's s(r) = 0.5 isosurface correlates strongly with the experimental red shift seen for bimolecular hydrogen-bonded complexes with alcohols as donor molecules and a variety of N-, O-, P-, and S-containing molecules as acceptors. 13 The kinetic energy density is calculated directly from the electron density with the equation 24,58 G r r r r r ( )…”

“…However, regions of low reduced density gradient can also occur without the presence of a BCP . It is possible to calculate the kinetic energy density evaluated within an isovolume with the boundary condition set to s ( r ) = 0.5, and this has been shown to be a good measure of the strength of the hydrogen-bonding interaction. ,,,, The kinetic energy density of a hydrogen bond’s s ( r ) = 0.5 isosurface correlates strongly with the experimental red shift seen for bimolecular hydrogen-bonded complexes with alcohols as donor molecules and a variety of N-, O-, P-, and S-containing molecules as acceptors . The kinetic energy density is calculated directly from the electron density with the equation , In this work, we calculate the integrated kinetic energy density G ( s 0.5 ) using Bonder, which allows the automatic identification of discrete NCI isosurfaces and the integration of various properties within each isosurface.…”

“…In addition to probing the basic structure of gas-phase lactic acid, we explore both intramolecular hydrogen bonding in lactic acid and its ability to form intermolecular hydrogen bonds, specifically with water. In recent years, there have been new developments in applying electron density topology methods, which have been proven useful to gauge the strength of hydrogen bonds and accurately characterize them. ,− Hydrogen bonding is naturally expected to have a major influence on the chemistry of lactic acid, as it is an α-hydroxy acid. Indeed, lactic acid is expected to form hydrogen bonds with water, other organic acids, or itself, including forming the cyclic lactic acid dimer.…”

Room Temperature Gas-Phase Detection and Gibbs Energies of Water Amine Bimolecular Complex Formation

“…The asymmetric band profile, with a tail extending toward higher wavenumbers, is typical for bands related to the OH b stretch in hydrogen bound complexes. ,,, Furthermore, ν OH b is typically red shifted and its intensity is significantly enhanced, compared with the corresponding OH-stretching fundamental band in the monomer . H 2 O has two highly coupled OH stretches, which become partly decoupled upon complex formation, and the decoupled OH stretch of H 2 O can be used as a reference with ν̃ OH = (ν̃ 1 + ν̃ 3 )/2 = (3657.1 cm –1 + 3755.9 cm –1 )/2 = 3706.5 cm –1 .…”

Selenoamides modulate dipole–dipole interactions in hydrogen bonded supramolecular polymers of 1,3,5-substituted benzenes

“…The entropic penalty of the supramolecular polymerization of c-SeBTA (DS e = À97 J mole À1 K À1 ) was comparable to that of c-SBTA 30,36 (DS e = À102.6 J mole À1 K À1 ), instead, and we speculate similar ordering between the homopolymers of c-SeBTA and c-SBTA. We rationalize these thermodynamic parameters with an increased dipole-dipole and charge transfer character of the diffuse Se-NH hydrogen bond, 21,37 which ultimately affords the increased thermal stability of the supramolecular polymers of c-SeBTA (more favorable DH e and very similar DS e compared to c-SBTA). Interestingly, the nucleation penalty, and hence cooperativity, of the supramolecular polymers of c-SBTA and c-SeBTA were comparable (s = 1.9 Â 10 À3 for c-SBTA, 30,36 and 3 Â 10 À4 for c-SeBTA).…”