Related Experiment Video
Updated: Jun 18, 2026
07:36
Versatile CO2 Transformations into Complex Products: A One-pot Two-step Strategy
Published on: November 9, 2019
Dual Diborane(4) Reactivity: Lewis Acid to Bind Lewis-Basic Substrates and Electron Donor For Substrate Reduction
Lea Haas1, Lucas Kistner1, Eva A M Roesky1
1Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany.
Chemistry (Weinheim an Der Bergstrasse, Germany)
|March 3, 2025
Summary
Novel diborane compounds show dual reactivity, acting as both Lewis acids and electron donors. Pyrazine coordination and methylation trigger electron transfer, creating intensely colored complexes with metallomimetic properties.
Area of Science:
- Organometallic Chemistry
- Boron Chemistry
- Coordination Chemistry
Background:
- Electron-rich diborane(4) molecules exhibit dual Lewis acid and electron donor reactivity.
- Guanidinate-substituted diboranes readily eliminate leaving groups to form monocationic species.
- Pyrazine derivatives are versatile ligands in coordination chemistry.
Purpose of the Study:
- To explore unprecedented reaction sequences involving pyrazine-diborane coordination compounds.
- To investigate the electron transfer triggered by pyrazine methylation and excess pyrazine.
- To evaluate the scope of novel metallomimetic reactivity in pyrazine-diborane complexes.
Main Methods:
- Synthesis and characterization of diborane-pyrazine coordination compounds.
- Triggering electron transfer via pyrazine methylation using MeOTf.
- Investigating electron transfer induced by excess pyrazine.
- Studying mono- and dicationic pyrazine-diborane complexes.
Main Results:
- Coordination compounds exhibit intense coloration due to B-B bond to pyrazine π* orbital electronic excitations.
- Pyrazine methylation successfully triggers electron transfer, enhancing pyrazine acceptor strength.
- Electron transfer can also be initiated by reaction with excess pyrazine.
- A range of pyrazine derivatives and resulting complexes were studied.
Conclusions:
- Diborane-pyrazine complexes display novel metallomimetic reactivity.
- Electron transfer in these systems can be controllably triggered by external stimuli.
- This work expands the understanding of diborane chemistry and its potential applications.
Related Concept Videos
02:55Exceptions to the Octet Rule
27.3K
Many covalent molecules have central atoms that do not have eight electrons in their Lewis structures. These molecules fall into three categories:
27.3K
02:33Lewis Acids and Bases
43.1K
In 1923, G. N. Lewis proposed a generalized definition of acid-base behavior in which acids and bases are identified by their ability to accept or to donate a pair of electrons and form a coordinate covalent bond.
A coordinate covalent bond (or dative bond) occurs when one of the atoms in the bond provides both bonding electrons. For example, a coordinate covalent bond occurs when a water molecule combines with a hydrogen ion to form a hydronium ion. A coordinate covalent bond also results when...
A coordinate covalent bond (or dative bond) occurs when one of the atoms in the bond provides both bonding electrons. For example, a coordinate covalent bond occurs when a water molecule combines with a hydrogen ion to form a hydronium ion. A coordinate covalent bond also results when...
43.1K
03:08Hydroboration-Oxidation of Alkenes
7.8K
In addition to the oxymercuration–demercuration method, which converts the alkenes to alcohols with Markovnikov orientation, a complementary hydroboration-oxidation method yields the anti-Markovnikov product. The hydroboration reaction, discovered in 1959 by H.C. Brown, involves the addition of a B–H bond of borane to an alkene giving an organoborane intermediate. The oxidation of this intermediate with basic hydrogen peroxide forms an alcohol.
7.8K
02:36Regioselectivity and Stereochemistry of Hydroboration
8.0K
A significant aspect of hydroboration–oxidation is the regio- and stereochemical outcome of the reaction.
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn...
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn...
8.0K
02:23Alcohols from Carbonyl Compounds: Reduction
10.2K
Reduction is a simple strategy to convert a carbonyl group to a hydroxyl group. The three major pathways to reduce carbonyls to alcohols are catalytic hydrogenation, hydride reduction, and borane reduction.
Catalytic hydrogenation is similar to the reduction of an alkene or alkyne by adding H2 across the pi bond in the presence of transition metal catalysts like Raney Ni, Pd–C, Pt, or Ru. Aldehydes and ketones can be reduced by this method, often under mild to moderate heat (25–100°C) and...
Catalytic hydrogenation is similar to the reduction of an alkene or alkyne by adding H2 across the pi bond in the presence of transition metal catalysts like Raney Ni, Pd–C, Pt, or Ru. Aldehydes and ketones can be reduced by this method, often under mild to moderate heat (25–100°C) and...
10.2K
01:14Electrophilic 1,2- and 1,4-Addition of X2 to 1,3-Butadiene
2.3K
Electrophilic addition of halogens to alkenes proceeds via a cyclic halonium ion to form a 1,2-dihalide or a vicinal dihalide.
2.3K