Related Experiment Video
Updated: May 7, 2026

Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
Published on: April 19, 2019
A zwitterionic carbanion frustrated by boranes--dihydrogen cleavage with weak Lewis acids via an "inverse" frustrated
Hui Li1, Adelia J A Aquino, David B Cordes
1Texas Tech University , Department of Chemistry & Biochemistry, Box 41061, Lubbock, Texas 79409-1061, United States.
Abstract:
The synthesis, structural characterization, and acid-base chemistry of [C(SiMe2OCH2CH2OMe)3]Na (2), a sterically encumbered zwitterionic organosodium compound, is reported. 2 is a strong Brønsted base that forms frustrated Lewis pairs (FLPs) with a number of boron-containing Lewis acids ranging from weakly Lewis acidic aryl and alkyl boranes to various alkyl borates. These intermolecular FLPs readily cleave H2, which confirms that even poor Lewis acids can engage in FLP-mediated H2 cleavage provided that the present bulky base is of sufficiently high Brønsted basicity.
Related Concept Videos
Hydroboration-Oxidation of Alkenes
Lewis Acids and Bases
Lewis Acids and Bases
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...
α-Bromination of Carboxylic Acids: Hell–Volhard–Zelinski Reaction
Exceptions to the Octet Rule
Regioselectivity and Stereochemistry of Hydroboration
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...

