Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Concept Videos

Complexation Equilibria: Factors Influencing Stability of Complexes01:09

Complexation Equilibria: Factors Influencing Stability of Complexes

494
In complexation reactions, metal cations are the electron pair acceptors, and the ligands are the electron pair donors. The stability of the metal complexes depends primarily on the complexing ability of the central metal ion and the nature of the ligands. Generally, the complexing ability of the metal ion depends on the size and charge of the ion. As the metal ion size increases, the stability of the metal complexes decreases, provided that the valency of the metal ion and the ligands remain...
494
Aromatic Hydrocarbon Cations: Structural Overview01:18

Aromatic Hydrocarbon Cations: Structural Overview

3.1K
Cycloheptatriene is a neutral monocyclic unsaturated hydrocarbon that consists of an odd number of carbon atoms and an intervening sp3 carbon in the ring. The three double bonds in the ring correspond to 6 π electrons, which is a Huckel number, and therefore satisfies the criteria of 4n + 2 π electrons. However, the intervening sp3 carbon disrupts the continuous overlap of p orbitals. As a result, cycloheptatriene is not aromatic.
Removing one hydrogen from the intervening CH2 group...
3.1K
Aromatic Hydrocarbon Anions: Structural Overview01:18

Aromatic Hydrocarbon Anions: Structural Overview

3.1K
Neutral hydrocarbons like cyclopentadiene with an odd number of carbon atoms and one intervening CH2 group in the ring are not aromatic. Cyclopentadiene with 4 π electrons does not satisfy the 4n + 2 π electron rule. Additionally, the intervening CH2 group is sp3 hybridized and lacks a vacant p orbital, thereby interrupting the overlap of p orbitals in a continuous manner and preventing the delocalization of π electrons throughout the ring.
Due to the absence of continuous...
3.1K
Radical Reactivity: Steric Effects01:10

Radical Reactivity: Steric Effects

2.0K
The presence of electron-donating, electron-withdrawing, or conjugating groups adjacent to a radical center, imparts electronic stabilization to the radicals. Examples of such electronically-stabilized radicals are triphenylmethyl, tetramethylpiperidine‐N‐oxide, and 2,2‐diphenyl‐1‐picrylhydrazyl. These radicals are remarkably stable and are known as persistent radicals. Some of the persistent radicals can even be isolated and purified.
Along with electronic...
2.0K
Nucleophilic Aromatic Substitution: Elimination–Addition01:11

Nucleophilic Aromatic Substitution: Elimination–Addition

4.1K
Simple aryl halides do not react with nucleophiles. However, nucleophilic aromatic substitutions can be forced under certain conditions, such as high temperatures or strong bases. The mechanism of substitution under such conditions involves the highly unstable and reactive benzyne intermediate. Benzyne contains equivalent carbon centers at both ends of the triple bond, each of which is equally susceptible to nucleophilic attack. This 50–50 distribution of products is...
4.1K
Criteria for Aromaticity and the Hückel 4n + 2 Rule01:20

Criteria for Aromaticity and the Hückel 4n + 2 Rule

11.5K
Like benzene, cyclobutadiene and cyclooctatetraene are cyclic compounds with alternate single and double bonds. However, their chemical behavior differs from benzene, as they are unstable and not aromatic. So, what are the structural characteristics of unsaturated compounds categorized as aromatic?  
For the first time, Eric Hückel, a German chemical physicist, derived a set of structural features for a compound to be classified as aromatic. This is now known as...
11.5K

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

Aromaticity-promoted oxygen-centered radical stability in α-hydroxy heterocyclics.

Physical chemistry chemical physics : PCCP·2026
Same author

Electron-injection-induced global aromaticity enables stable open-shell nanopillars with intense mid-infrared magnetic circular dichroism.

Chemical science·2026
Same author

Evaluating the Performance of GPT-4.0 in Generating and Refining Multiple-Choice Questions for Dental Education.

European journal of dental education : official journal of the Association for Dental Education in Europe·2026
Same author

Substituent-modulated adaptive aromaticity in NHC-pyrrolyl cations: a combined DFT and machine learning study.

Physical chemistry chemical physics : PCCP·2026
Same author

Fully cove-edged bilayer nanographene with parallel displaced stacking.

Nature communications·2026
Same author

Resveratrol alleviates lipid deposition, endoplasmic reticulum stress, inflammation and apoptosis in the livers of large yellow croaker (<i>Larimichthys crocea</i>) fed with a soybean oil-based diet.

Animal nutrition (Zhongguo xu mu shou yi xue hui)·2026

Related Experiment Video

Updated: Sep 20, 2025

Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
10:44

Isolating Free Carbenes, their Mixed Dimers and Organic Radicals

Published on: April 19, 2019

11.0K

Stabilizing a 20-Electron Metallaazulyne by Aromaticity.

Rulin Qiu1, Jiashun Wu1, Jun Zhu1

  • 1State Key Laboratory of Physical Chemistry of Solid Surfaces, Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, People's Republic of China.

Inorganic Chemistry
|June 8, 2022
PubMed
Summary

Researchers demonstrate a stable 20-electron compound, a metallaazulyne, by leveraging aromaticity. This finding challenges the 18-electron rule and opens new avenues for stabilizing unusual electron counts in metal complexes.

More Related Videos

Accessing Valuable Ligand Supports for Transition Metals: A Modified, Intermediate Scale Preparation of 1,2,3,4,5-Pentamethylcyclopentadiene
09:45

Accessing Valuable Ligand Supports for Transition Metals: A Modified, Intermediate Scale Preparation of 1,2,3,4,5-Pentamethylcyclopentadiene

Published on: March 20, 2017

10.6K
Preparation of a Corannulene-functionalized Hexahelicene by CopperI-catalyzed Alkyne-azide Cycloaddition of Nonplanar Polyaromatic Units
09:35

Preparation of a Corannulene-functionalized Hexahelicene by CopperI-catalyzed Alkyne-azide Cycloaddition of Nonplanar Polyaromatic Units

Published on: September 18, 2016

11.6K

Related Experiment Videos

Last Updated: Sep 20, 2025

Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
10:44

Isolating Free Carbenes, their Mixed Dimers and Organic Radicals

Published on: April 19, 2019

11.0K
Accessing Valuable Ligand Supports for Transition Metals: A Modified, Intermediate Scale Preparation of 1,2,3,4,5-Pentamethylcyclopentadiene
09:45

Accessing Valuable Ligand Supports for Transition Metals: A Modified, Intermediate Scale Preparation of 1,2,3,4,5-Pentamethylcyclopentadiene

Published on: March 20, 2017

10.6K
Preparation of a Corannulene-functionalized Hexahelicene by CopperI-catalyzed Alkyne-azide Cycloaddition of Nonplanar Polyaromatic Units
09:35

Preparation of a Corannulene-functionalized Hexahelicene by CopperI-catalyzed Alkyne-azide Cycloaddition of Nonplanar Polyaromatic Units

Published on: September 18, 2016

11.6K

Area of Science:

  • Organometallic Chemistry
  • Computational Chemistry
  • Aromaticity Studies

Background:

  • The 18-electron rule is a fundamental principle governing the stability of transition metal complexes.
  • Compounds with 20 valence electrons are exceptionally rare due to the perceived violation of this rule.

Purpose of the Study:

  • To computationally investigate the possibility of stabilizing a 20-electron species.
  • To explore the role of aromaticity in stabilizing such unusual electron counts.

Main Methods:

  • Density functional theory (DFT) calculations were employed.
  • Various aromaticity indices, including nucleus-independent chemical shift (NICS) and anisotropy of the induced current density (ACD), were used for validation.

Main Results:

  • A stable 20-electron metallaazulyne complex was successfully designed and characterized.
  • Introduction of a transition metal (osmium) into azulyne initially resulted in an antiaromatic species.
  • Reduction of the osmaazulyne by two electrons led to a stable, aromatic 20-electron system.

Conclusions:

  • Aromaticity can be a powerful tool for stabilizing 20-electron metal complexes, challenging the traditional 18-electron rule.
  • This work provides a theoretical framework for the design of novel organometallic compounds with non-standard electron counts.
  • The findings encourage experimental efforts to synthesize and verify these predicted 20-electron aromatic species.