Theoretical study on the structures and vibrational spectra of the H2SO4–(CO2)x (x=1, 2) hydrogen bonded complexes

Bieńko, Agnieszka J.; Latajka, Zdzisław

doi:10.1016/s0009-2614(03)00768-1

Cited by 5 publications

(5 citation statements)

References 14 publications

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“…The enthalpy of complexation Δ H (in vacuum) in complex C1 is found to be −12.0 kcal/mol at the B3LYP and MP2 levels of theory, whereas Δ H in toluene (B3LYP) was −10.7 kcal/mol. With respect to the B3LYP values, the calculated MP2 values for the enthalpy of complex formation for phosphine oxide−phenol complexes are typically equal or slightly more negative, in line with trends from the literature . Results show that complex formation in toluene is slightly less favorable than in vacuum, by ∼1.3 kcal/mol.…”

Section: Resultssupporting

confidence: 81%

“…With respect to the B3LYP values, the calculated MP2 values for the enthalpy of complex formation for phosphine oxide-phenol complexes are typically equal or slightly more negative, in line with trends from the literature. 51 Results show that complex formation in toluene is slightly less favorable than in vacuum, by ∼1.3 kcal/mol. This indicates a minor solvent effect, as was also clear from the solvation energies of the solutes and complexes.…”

Section: Resultsmentioning

confidence: 93%

“…In addition, toluene presents only a minor influence on hydrogen bonding interactions, and it is a good solvent for the compounds that are under investigation. Many investigations on hydrogen bonding describe experimental work that is carried out in toluene, and clearly indicate that this solvent does not affect hydrogen bond formation much. − Hydrogen bonds in all kinds of systems have been extensively studied by density functional theory. ,,− In this work, molecular modeling experiments have been applied to investigate the complex formation. The geometries of the monomers and complexes have all been optimized at the B3LYP/6-311G(d,p) level of theory, which generally describes the geometries of these systems well.…”

Section: Introductionmentioning

confidence: 99%

“…[45][46][47] Hydrogen bonds in all kinds of systems have been extensively studied by density functional theory. 23,24,[48][49][50][51][52][53] In this work, molecular modeling experiments have been applied to investigate the complex formation. The geometries of the monomers and complexes have all been optimized at the B3LYP/6-311G(d,p) level of theory, Although analysis of a small data set of hydrogen-bonded complexes suggests that other density functionals might perform somewhat better in describing hydrogen-bonding interactions, 54 no analysis has been presented in the literature that includes a series of compounds with sulfur or phosphor atoms, and therefore the widely used B3LYP functional was used here.…”

Section: Introductionmentioning

confidence: 99%

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Complexation of Phenols and Thiophenol by Phosphine Oxides and Phosphates. Extraction, Isothermal Titration Calorimetry, and ab Initio Calculations

et al. 2008

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To develop a new solvent-impregnated resin system for the removal of phenols from water the complex formation of triisobutylphosphine sulfide (TIBPS), tributylphosphate (TBP), and tri-n-octylphosphine oxide (TOPO) with a series of phenols (phenol, thiophenol, 3-chlorophenol, 3,5-dichlorophenol, 4-cyanophenol, and pentachlorophenol) was studied. The investigation of complex formation between the extractants and the phenols in the solvent toluene was carried out using liquid-liquid extraction, isothermal titration calorimetry (ITC), and quantum chemical modeling (B3LYP/6-311+G(d,p)//B3LYP/6-311G(d,p) and MP2/6-311++G(2d,2p)//B3LYP/6-311G(d,p)). The equilibrium constant (binding affinity, Kchem), enthalpy of complex formation (DeltaH), and stoichiometry (N) were directly measured with ITC, and the entropy of complexation (DeltaS) was derived from these results. A first screening of K chem toward phenol revealed a very high binding affinity for TOPO, and very low binding affinities for the other extractants. Modeling results showed that although 1:1 complexes were formed, the TIBPS and TBP do not form strong hydrogen bonds. Therefore, in the remainder of the research only TOPO was considered. Kchem of TOPO for the phenols in toluene increased from 1,000 to 10,000 M(-1) in the order phenol < pentachlorophenol < 3-chlorophenol < 4-cyanophenol approximately 3,5-dichlorophenol (in line with their pKa values, except for pentachlorophenol) in the absence of water, while the stoichiometric ratio remained 1:1. In water-saturated toluene, the binding affinities are lower due to co-complexation of water with the active site of the extractant. The increase in binding affinity for TOPO in the phenol series was confirmed by a detailed ab initio study, in which Delta H was calculated to range from -10.7 kcal/mol for phenol to -13.4 kcal/mol for 4-cyanophenol. Pentachlorophenol was found to behave quite differently, showing a DeltaH value of -10.5 kcal/mol. In addition, these calculations confirm the formation of 1:1 H-bonded complexes.

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Section: Resultssupporting

confidence: 81%

Section: Resultsmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Complexation of Phenols and Thiophenol by Phosphine Oxides and Phosphates. Extraction, Isothermal Titration Calorimetry, and ab Initio Calculations

et al. 2008

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“…Typically, the B3LYP data underestimate the stability of the H-bonded complex (by 2-5 kcal mol À1 with respect to MP2/CBS) in line with reported trends, [43] while M06-2X performs very well, typically within 1 kcal mol À1 of the MP2/ CBS data after BSSE correction. As shown in Table 3, the differences between the MP2/6-311 + G(d,p) and SCS-MP2/6-311 + G(d,p) data are small (0.9-1.5 kcal mol .…”

supporting

confidence: 76%

Hydrogen Bonding in Phosphine Oxide/Phosphate–Phenol Complexes

2010

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To develop a new solvent-impregnated resin (SIR) system for the removal of phenols and thiophenols from water, complex formation by hydrogen bonding of phosphine oxides and phosphates is studied using isothermal titration calorimetry (ITC) and quantum chemical modeling. Six different computational methods are used: B3LYP, M06-2X, MP2, spin component-scaled (SCS) MP2 [all four with 6-311+G(d,p) basis set], a complete basis set extrapolation at the MP2 level (MP2/CBS), and the composite CBS-Q model. This reveals a range of binding enthalpies (DeltaH) for phenol-phosphine oxide and phenol-phosphate complexes and their thio analogues. Both structural (bond lengths/angles) and electronic elements (charges, bond orders) are studied. Furthermore, solvent effects are investigated theoretically by the PCM solvent model and experimentally via ITC. From our calculations, a trialkylphosphine oxide is found to be the most promising extractant for phenol in SIRs, yielding DeltaH=-14.5 and -9.8 kcal mol(-1) with phenol and thiophenol, respectively (MP2/CBS), without dimer formation that would hamper the phenol complexation. In ITC measurements, the DeltaH of this complex was most negative in the noncoordinating solvent cyclohexane, and slightly less so in pi-pi interacting solvents such as benzene. The strongest binding is found for the dimethyl phosphate-phenol complex [-15.1 kcal mol(-1) (MP2/CBS)], due to the formation of two H-bonds (P=OH-O- and P-O-HO-H); however, dimer formation of these phosphates competes with complexation of phenol, and would thus hamper their use in industrial extractions. CBS-Q calculations display erroneous trends for sulfur compounds, and are found to be unsuitable. Computationally relatively cheap SCS-MP2 and M06-2X calculations did accurately agree with the much more elaborate MP2/CBS method, with an average deviation of less than 1 kcal mol(-1).

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