Related Experiment Video
Updated: Aug 23, 2026

Chemoselective Preparation of 1-Iodoalkynes, 1,2-Diiodoalkenes, and 1,1,2-Triiodoalkenes Based on the Oxidative Iodination of Terminal Alkynes
Published on: September 12, 2018
Submillimeter-wave spectra of hypoiodous acid
1ISS Science Project Office, Japan Aerospace Exploration Agency, Tsukuba Space Center, 2-1-1 Sengen, Tsukuba 305-8585, Japan. ozeki.hiroyuki@jaxa.jp
Abstract:
Pure rotational spectra of hypoiodous acid, HOI, and its deuterated species, DOI, were measured in the frequency range of 320-670 GHz. The molecule was efficiently produced by a reaction of atomic oxygen with iodoethane. Rotational constants and centrifugal distortion constants for the molecule were determined accurately. The vibrationally averaged structure for HOI was obtained by taking the isotopic difference of the OH bond length into consideration: r(z)(OH)=0.967(8) A, r(z)(OI)=1.9941(3) A, and theta(z)(HOI)=103.89 degrees, where the errors were estimated from the residual inertial defect. Equilibrium bond lengths for the OH and OI bonds were derived as 0.959(8) A and 1.9874(3) A, respectively, by assuming anharmonic constants of the corresponding diatomic molecules. Electric-quadrupole interaction constants and nuclear-spin-rotation coupling constants for the iodine nucleus were obtained. Nonaxial terms of the electric-quadrupole constant for HOI can be determined as well, which enabled us to derive the principal values of the coupling tensor. The values obtained were used to gauge the ionicity of the X-O bond in the HOX molecular system. The nuclear-spin-rotation coupling constant along the a inertial axis is found to be significantly smaller than others, which may be explained by a contribution from two low-lying singlet excited states.
Related Concept Videos
Spectroscopy of Carboxylic Acid Derivatives
In the...
IR and UV–Vis Spectroscopy of Carboxylic Acids
However, the stretching absorptions for the C=O bond vary depending on the structure of carboxylic acids. The C=O bond of the free carboxylic acids shows a higher stretching frequency, 1760 cm−1, while H-bonded carboxylic acids (dimers) exhibit stretching absorptions at a lower frequency, 1710 cm−1. The C=O bond of the...
IR Spectrum Peak Broadening: Hydrogen Bonding
However, the extent of hydrogen bonding influences the observed stretching frequency and band broadening. Intermolecular or intramolecular hydrogen bonding...
IR Spectroscopy: Hooke's Law Approximation of Molecular Vibration
According to Hooke's law, the vibrational frequency is directly proportional to the...
IR Spectroscopy: Molecular Vibration Overview
Stretching vibrations are vibrational motions that occur along the bond line, changing the bond length or distance between two bonded atoms. They are further distinguished as symmetric or asymmetric. In symmetric stretching, the...
IR Frequency Region: X–H Stretching

