Related Experiment Video
Updated: Sep 19, 2025
06:44
From Molecules to Materials: Engineering New Ionic Liquid Crystals Through Halogen Bonding
Published on: March 24, 2018
69.2K
Spectroscopic Implications for [N-X-N]+ (X = I, Br)-Type Halonium Compounds with Formal Hypervalency
Satoru Muramatsu1, Akihito Matsuyama1, Daiki Iwanaga1
1Department of Chemistry, Graduate School of Advanced Science and Engineering, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima-shi, Hiroshima 739-8526, Japan.
Inorganic Chemistry
|June 18, 2025
Summary
Bis(pyridine)halonium complexes exhibit unique electronic structures. Spectroscopic analysis reveals charge-transfer transitions and quantifies halogen bond strength, offering new insights into hypervalency.
Area of Science:
- Inorganic Chemistry
- Spectroscopy
- Computational Chemistry
Background:
- Bis(pyridine)halonium complexes ([Py2X]+) are hypervalent species with 10 valence electrons.
- Understanding the electronic structure and bonding in these complexes is crucial for advancing hypervalency research.
Purpose of the Study:
- To investigate the gas-phase UV spectra of bis(pyridine)halonium complexes ([Py2X]+).
- To elucidate the electronic states and bonding characteristics of these hypervalent species.
- To provide a spectroscopic perspective on hypervalency.
Main Methods:
- Gas-phase UV spectroscopy using a cryogenic ion trap.
- Analysis of vibronic structures and spectral band characteristics.
- Quantitative estimation of N-X bond force constants.
Main Results:
- Observed distinct vibronic structures for charge-transfer (CT) transitions, indicating halogen bonds.
- Identified broad spectral bands at higher energies attributed to three-center, four-electron (3c-4e) bond orbitals.
- Proposed charge-resonance (CR) interactions between charge-localized states to describe electronic states.
- Quantitatively estimated N-X bond force constants for X=Br (159 N·m⁻¹) and X=I (132 N·m⁻¹).
Conclusions:
- The electronic states of [Py2X]+ complexes are influenced by significant charge-resonance interactions.
- Spectroscopic data provides a new perspective on the nature of hypervalency.
- The observed differences in force constants correlate with the magnitude of electron transfer during CT excitation.
![The Synthesis of [Sn10SiSiMe334]2- Using a Metastable SnI Halide Solution Synthesized via a Co-condensation Technique](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F54498.jpg&w=3840&q=50)
Related Concept Videos
02:38Electrophilic Addition to Alkynes: Halogenation
8.8K
Introduction
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
8.8K
01:13¹H NMR: Complex Splitting
1.4K
A proton M that is coupled to a proton X results in doublet signals for M. However, NMR-active nuclei can be simultaneously coupled to more than one nonequivalent nucleus. When M is coupled to a second proton A, such as in styrene oxide, each peak in the doublet is split into another doublet.
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied...
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied...
1.4K
02:55Exceptions to the Octet Rule
29.9K
Many covalent molecules have central atoms that do not have eight electrons in their Lewis structures. These molecules fall into three categories:
29.9K
02:45Alkyl Halides
17.5K
Structural Properties
Alkyl halides are halogen-substituted alkanes wherein one or more hydrogen atoms of an alkane is replaced by a halogen atom such as fluorine, chlorine, bromine, or iodine. The carbon atom in an alkyl halide is bonded to the halogen atom, which is sp3-hybridized and exhibits a tetrahedral shape.
Unlike alkyl halides, compounds in which a halogen atom is bonded to an sp2 -hybridized carbon atom of a carbon-carbon double bond (C=C) are called vinyl halides. Whereas aryl...
Alkyl halides are halogen-substituted alkanes wherein one or more hydrogen atoms of an alkane is replaced by a halogen atom such as fluorine, chlorine, bromine, or iodine. The carbon atom in an alkyl halide is bonded to the halogen atom, which is sp3-hybridized and exhibits a tetrahedral shape.
Unlike alkyl halides, compounds in which a halogen atom is bonded to an sp2 -hybridized carbon atom of a carbon-carbon double bond (C=C) are called vinyl halides. Whereas aryl...
17.5K
03:24Hybridization of Atomic Orbitals I
49.3K
The mathematical expression known as the wave function, ψ, contains information about each orbital and the wavelike properties of electrons in an isolated atom. When atoms are bound together in a molecule, the wave functions combine to produce new mathematical descriptions that have different shapes. This process of combining the wave functions for atomic orbitals is called hybridization and is mathematically accomplished by the linear combination of atomic orbitals. The new orbitals that...
49.3K
02:46Halogenation of Alkenes
16.5K
Halogenation is the addition of chlorine or bromine across the double bond in an alkene to yield a vicinal dihalide. The reaction occurs in the presence of inert and non-nucleophilic solvents, such as methylene chloride, chloroform, or carbon tetrachloride.
Consider the bromination of cyclopentene. Molecular bromine is polarized in the proximity of the π electrons of cyclopentene. An electrophilic bromine atom adds across the double bond, forming a cyclic bromonium ion intermediate.
Consider the bromination of cyclopentene. Molecular bromine is polarized in the proximity of the π electrons of cyclopentene. An electrophilic bromine atom adds across the double bond, forming a cyclic bromonium ion intermediate.
16.5K