Exploiting Electrostatics To Generate Unsaturation: Oxidative Ge=E Bond Formation Using a Non π-Donor Stabilized
Arnab Rit1, Rémi Tirfoin2, Simon Aldridge3
1Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 3QR (UK). arnab.rit@chem.ox.ac.uk.
Angewandte Chemie (International Ed. in English)
|November 8, 2015
Summary
Researchers synthesized a novel germanium cation lacking typical stabilization, enabling new Group 14 metal-carbon and metal-nitrogen multiple bonds. This breakthrough opens avenues for creating unique, less bulky chemical structures.
Area of Science:
- Organometallic Chemistry
- Main Group Chemistry
Background:
- Two-coordinate germanium cations are typically stabilized by pi-donor ligands.
- A lack of pi-donor stabilization leads to unique electronic properties and reactivity.
Purpose of the Study:
- To synthesize and characterize a two-coordinate germanium cation without pi-donor stabilization.
- To explore the reactivity of this novel cation in oxidative bond-forming reactions.
- To access new Group 14 metal compounds with multiple bonds.
Main Methods:
- Synthesis of the target germanium cation using specific ligand precursors.
- Spectroscopic and crystallographic characterization of the synthesized cation.
- Investigation of its reactivity through various oxidative coupling reactions.
Main Results:
- Successful synthesis of the two-coordinate germanium cation [(IDipp){(Me3Si)2CH}Ge:](+).
- The cation exhibits a small HOMO-LUMO gap (187 kJ/mol) due to lack of pi-stabilization.
- Facile formation of Group 14 metal-carbon (M=C) and metal-nitrogen (M=N) multiple bonds.
- Access to less sterically demanding systems using electrostatic stabilization strategies.
Conclusions:
- The synthesized germanium cation is a versatile precursor for novel organometallic compounds.
- This work demonstrates a new strategy for stabilizing reactive metal centers.
- Opens possibilities for the development of new materials and catalysts based on Group 14 elements.
More Related Videos
Related Concept Videos
02:04Oxidation of Alkenes: Anti Dihydroxylation with Peroxy Acids
8.1K
Diols are compounds with two hydroxyl groups. In addition to syn dihydroxylation, diols can also be synthesized through the process of anti dihydroxylation. The process involves treating an alkene with a peroxycarboxylic acid to form an epoxide. Epoxides are highly strained three-membered rings with oxygen and two carbons occupying the corners of an equilateral triangle. This step is followed by ring-opening of the epoxide in the presence of an aqueous acid to give a trans diol.
8.1K
01:26Photochemical Electrocyclic Reactions: Stereochemistry
2.4K
The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
Selection Rules: Photochemical Activation
Selection Rules: Photochemical Activation
2.4K
01:17Thermal Electrocyclic Reactions: Stereochemistry
2.7K
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.
2.7K
02:24Introduction to Electrophilic Addition Reactions of Alkenes
11.4K
The double bond in a simple, unconjugated alkene is a region of high electron density that can act as a weak base or a nucleophile. The filled π orbital (HOMO) of the double bond can interact with the empty LUMO of an electrophile. A bonding interaction occurs when the electrophile attacks between the two carbons; the electrophile then accepts a pair of electrons from the π bond and undergoes addition across the double bond, yielding a single product.
Addition and elimination...
Addition and elimination...
11.4K
01:23Reactivity of Enolate Ions
3.5K
Enolate ions are formed by the acid–base reaction of a carbonyl compound with a base. This leads to deprotonation of the α hydrogen atom, leading to a resonance-stabilized enolate ion where one of the contributing structures is an oxyanion, which imparts additional stability. Therefore, the proton on the α carbon is more acidic in nature than that of other sp3-hybridized C–H bonds but less acidic than those in O–H bonds where the negative charge in the conjugate...
3.5K
01:33Regioselective Formation of Enolates
3.7K
As depicted in the figure below, the unsymmetrical ketones can form two possible enolates: less substituted or more substituted enolates. Usually, the thermodynamic enolates are formed from the more substituted α-carbon atom, while the kinetic enolates are formed faster by deprotonation from the less substituted position. The thermodynamic enolates have lower energy, so they are more stable. But the energy required to form kinetic enolates is less.
3.7K