Related Experiment Video
Updated: Aug 26, 2025
14:07
Preparation and Use of Carbonyl-decorated Carbenes in the Activation of White Phosphorus
Published on: October 3, 2014
13.7K
C-H Activation by Isolable Cationic Bis(phosphine) Cobalt(III) Metallacycles
William G Whitehurst1, Junho Kim1, Stefan G Koenig2
1Department of Chemistry, Frick Laboratory, Princeton University, Princeton, New Jersey 08544, United States.
Journal of the American Chemical Society
|October 4, 2022
Summary
This study synthesized cobalt(III) metallacycle complexes that efficiently activate C-H bonds, leading to ortho-alkylation. These findings support the role of cobalt metallacycles in catalytic C-H functionalization reactions.
Area of Science:
- Organometallic Chemistry
- Catalysis
- Synthetic Chemistry
Background:
- Cobalt complexes are increasingly studied for catalytic applications.
- C-H activation is a key transformation in organic synthesis.
- Understanding reaction mechanisms is crucial for catalyst development.
Purpose of the Study:
- To synthesize novel cationic bis(phosphine) cobalt(III) metallacycle complexes.
- To investigate their ability to promote directed C(sp2)-H activation.
- To provide experimental evidence for the role of cobalt metallacycles in catalysis.
Main Methods:
- Synthesis of five- and six-coordinate cobalt(III) metallacycles.
- Evaluation of catalytic activity in C-H activation reactions.
- Deuterium labeling and kinetic studies to probe the reaction mechanism.
Main Results:
- Facile directed C(sp2)-H activation was achieved with exclusive ortho-alkylation selectivity.
- Direct observation of C-H activation by cobalt(III) metallacycles was successful.
- Studies provided insights into C-H bond cleavage and C-C bond reductive elimination.
Conclusions:
- The synthesized cobalt(III) metallacycles are effective catalysts for directed C-H activation.
- These findings offer experimental support for cobalt metallacycle intermediates in catalytic C-H functionalization.
- The study elucidates key mechanistic steps in cobalt-catalyzed reactions.
Related Concept Videos
02:34Structural Isomerism
19.6K
Isomerism in Complexes
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can...
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can...
19.6K
02:42Valence Bond Theory
9.1K
Coordination compounds and complexes exhibit different colors, geometries, and magnetic behavior, depending on the metal atom/ion and ligands from which they are composed. In an attempt to explain the bonding and structure of coordination complexes, Linus Pauling proposed the valence bond theory, or VBT, using the concepts of hybridization and the overlapping of the atomic orbitals. According to VBT, the central metal atom or ion (Lewis acid) hybridizes to provide empty orbitals of suitable...
9.1K
01:23Properties of Organometallic Compounds
1.1K
Organometallic compounds are compounds that contain a carbon–metal bond. Carbon belongs to an organyl group like alkyl, aryl, allyl, or benzyl groups. The metal can be from Group I or Group II of the periodic table, a transition metal, or a semimetal.
1.1K
02:52Stereoisomerism
12.3K
Isomerism in Complexes
Isomers are different chemical species that have the same chemical formula.
Transition metal complexes often exist as geometric isomers, in which the same atoms are connected through the same types of bonds but with differences in their orientation in space. Coordination complexes with two different ligands in the cis and trans positions from a ligand of interest form isomers. For example, the octahedral [Co(NH3)4Cl2]+ ion has two isomers (Figure 1) In the cis...
Isomers are different chemical species that have the same chemical formula.
Transition metal complexes often exist as geometric isomers, in which the same atoms are connected through the same types of bonds but with differences in their orientation in space. Coordination complexes with two different ligands in the cis and trans positions from a ligand of interest form isomers. For example, the octahedral [Co(NH3)4Cl2]+ ion has two isomers (Figure 1) In the cis...
12.3K
01:17Thermal Electrocyclic Reactions: Stereochemistry
2.1K
The stereochemistry of electrocyclic reactions is strongly influenced by the orbital symmetry of the polyene HOMO. Under thermal conditions, the reaction proceeds via the ground-state HOMO.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
2.1K
02:10Carbocations
11.5K
Carbocations are one of the reaction intermediates formed during several nucleophilic substitutions or elimination reactions. A carbocation is an electron-deficient species with the central carbon atom having six electrons and three bonded atoms. The central carbon in a carbocation is sp2 hybridized with trigonal planar geometry. It has an empty p orbital perpendicular to the plane of the structure that can accept electrons. Thus, carbocations act as strong electrophiles and may react with any...
11.5K