Probing Small Protonated Water Clusters in Acetonitrile Solutions by 1H NMR
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Mark V. Sigalov
Abstract
In a previous publication by Kalish et al. (J. Phys. Chem. A 115 (2011) 4063) the existence of well defined small protonated water clusters in acetonitrile has been established by IR spectroscopy. Here we report on a 1H NMR study of triflic acid, CF3SO3H, in acetonitrile-water solutions. Using NMR we are able to corroborate the general solvation scheme we have proposed for the hydrated proton in acetonitrile as a function of the molar ratio between the strong mineral acid and water, n = [H2O]/[acid]. According to this scheme, backed now by both IR absorption spectroscopy and NMR measurements, the very strong triflic acid completely dissociates in acetonitrile/water solutions to yield the aqueous proton and the triflate anion when n > 1. Furthermore, increasing n results in the proton solvated in increasingly larger water clusters formed within the acetonitrile solution.
Clearly distinguishable by NMR are the smallest protonated water clusters, the protonated water monomer, H3+O, and the protonated water dimer, H5+O2, which dominate the solution for n = 1,2,3. For larger n the NMR study indicates the gradual increase of the average protonated water cluster size as a function of n while the proton inner solvation core more closely retaining the characteristics of a deformed protonated water dimer, (H2O-H+⋯OH2)s than that of the protonated water monomer (H3+O)s.
© by Oldenbourg Wissenschaftsverlag, München, Germany
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Articles in the same Issue
- Editorial
- Biography of Prof. Dr. Hans-Heinrich Limbach
- Alumni and long term guests of the Limbach group
- NMR and FT-IR Studies on the Association of Derivatives of Thymidine, Adenosine, and 6-N-Methyl-Adenosine in Aprotic Solvents
- Competition between Hydrogen Bonds and Lewis Acid-Base Interactions in the Equilibria between Bis(pentafluorophenyl)borinic Acid and Pyridine: Insights from NMR, Diffractometric and Computational Studies
- Energy Analysis of Competing Non-Covalent Interaction in 1:1 and 1:2 Adducts of Collidine with Benzoic Acids by Means of X-Ray Diffraction
- A TT Dinucleotide with a Nonionic Silyl Backbone: Impact on Conformation and H-Bond Mediated Base Pairing as Studied by Low-Temperature NMR
- Oxygen and Hydrogen Isotopic Preference in Hydration Spheres of Chloride and Sulfate Ions
- Ab Initio Study of Cooperative Effects in Complexes X:HBO:Z, with X, Z=LiH, HNC, HF, HCN, HCl, ClF, and HBO: Structures, Binding Energies, and Spin-Spin Coupling Constants across Intermolecular Bonds
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- Acridine – a Promising Fluorescence Probe of Non-Covalent Molecular Interactions
- First Example of Hydrogen Bonding to Platinum Hydride
- Interaction of Hydrogen with a Cobalt(0001) Surface
- Immobilization and Characterization of RuCl2(PPh3)3 Mesoporous Silica SBA-3
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- Probing Small Protonated Water Clusters in Acetonitrile Solutions by 1H NMR
- Double Hydrogen Transfer in Low Symmetry Porphycenes
- Nuclear Spin Selective Torsional States: Implications of Molecular Symmetry
