Strong Quantum Coupling in the Vibrational Signatures of a Symmetric Ionic Hydrogen Bond: The Case of (CH3OH)2H(.)
Jake A Tan1,2,3, Jer-Lai Kuo1,3
1Molecular Science and Technology Program, Taiwan International Graduate Program, Academia Sinica , 128 Academia Road, Section 2, Nangang, Taipei 115, Taiwan, ROC.
Abstract:
Vibrational coupling between proton and flanking group motions in the ionic hydrogen bond (IHB) of (CH3OH)2H(+) were studied by solving reduced-dimension vibrational Schrödinger equations. Potential energy and dipole surfaces along a few key normal modes were constructed with high-level ab initio methods. It was found that the IHB stretch parallel to O-O axis strongly couples with the out-of-phase C-O stretch and out-of-phase in-plane CH3 rock with COH deformation. Such strong quantum coupling leads to a complex triplet at 850-1100 cm(-1) region. Furthermore, we have investigated the possible active role of torsional motion in intensity redistribution.
Related Concept Videos
Spin–Spin Coupling: One-Bond Coupling
IR Spectrum Peak Broadening: Hydrogen Bonding
However, the extent of hydrogen bonding influences the observed stretching frequency and band broadening. Intermolecular or intramolecular...
¹H NMR: Long-Range Coupling
In alkenes, spin information is communicated via σ–π overlap, as seen in allylic (four-bond) and homoallylic (five-bond) couplings. These coupling interactions are stronger when the σ bond is parallel to the alkene...
IR Spectroscopy: Hooke's Law Approximation of Molecular Vibration
According to Hooke's law, the vibrational frequency is directly proportional to...
Spin–Spin Coupling: Three-Bond Coupling (Vicinal Coupling)
The extent of coupling depends on the C‑C bond length, the two H‑C‑C angles, any electron-withdrawing substituents, and the dihedral angle between the involved orbitals. The...
Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)
The central atom need not be NMR-active because its electrons are affected by the electron polarization of the spin-active atoms. However, spin information is transmitted less effectively than in one-bond coupling, and 2J values are usually weaker than 1J values. The energy of...


