Structurally Symmetrical N+H.cntdot. .cntdot. .cntdot.N .rdblhar. N.cntdot. .cntdot. .cntdot.H+N Bonds. The Proton Potential as a Function of the pKa of the N-Base. FTIR Results and Quantum Chemical Calculations

Abstract

Ten substituted pyridinium-pyridine systems were studied in the middle and far infrared region as binary systems and as acetonitrile solutions. Furthermore, quantum chemical calculations of these systems were performed. All systems show an intense infrared continuum. The continuum does not change with the pK, of the protonated N-base in the pK, range 2.5-6.5. The hydrogen bond vibration vu in the far infrared region was found in all systems, and its wavenumber changes are caused by the change of the mass of the N-base. Almost no change in the harmonic force constant of the hydrogen bond vibration is found. Quantum chemical calculations yield a double minimum proton potential with no change of the barrier height of the well. Therefore, all systems show almost the same proton polarizability, resulting in continua with the same intensity distribution. For the systems, effective hydrogen bond vibration masses are calculated with various methods, and the obtained results are compared.

Deuteration of Water Enables Self‐Organization of Phospholipid‐Based Reverse Micelles

“…[23] They evidence hydron transfer under the influence of their electric charges, as rationalized by Stoyanov. [7] These hydron transfers occur between two potential wells separated by a barrier on the proton-donor-acceptor potential surface.…”

“…. [23] Moreover, the N-N distance between the wells is as small as 2.495 . [23] Consequently, according to recent studies by Stoyanov and co-workers, [4,7] in our system the hydron transfer along the NH + ···N bond in pyridine should be facilitated.…”

“…The BB1 band is reminiscent of the one observed with mixtures of pyridinium salts and pyridine. [23] It has been assigned to a hydron transfer between the pyridinium ions and [D 5 ]Py along an NÀH + (D + )···N bond. As rationalized by Stoyanov, [7] this assignment is supported by the merging into BB1 upon heating of the [D 5 ]PyH + n(NÀH + ) stretch, which appears as a spike at 2458 cm À1 [22] on the DOD stretch (Supporting Information, SI 1 A).…”

Molecular Heteroconjugation Equilibria in (n-Butylamine + Acetic Acid) Systems in Binary (Dimethyl Sulfoxide + 1,4-Dioxane) Solvent Mixtures

“…In non-aqueous media, relatively, wellexplored are equilibria of acid-base dissociation of both molecular (1) and cationic acids (2), as well as those of anionic homoconjugation (3), and more recently, of cationic homoconjugation (4):…”

A potentiometric study of molecular heteroconjugation equilibria in (n-butylamine+acetic acid) systems in binary (acetonitrile +1,4-dioxane) solvent mixtures

“…Using proton donors of increasing strength results in complexes of progressively stronger and more symmetric hydrogen bonds within which the so-called partial proton transfer takes place [3][4][5]:…”