Geometrically Constrained Organoboron Species as Lewis Superacids and Organic Superbases.
Angew Chem Int Ed Engl
; 62(36): e202308467, 2023 Sep 04.
Article
in En
| MEDLINE
| ID: mdl-37395499
ABSTRACT
This report unveils an advancement in the formation of a Lewis superacid (LSA) and an organic superbase by the geometrical deformation of an organoboron species towards a T-shaped geometry. The boron dication [2]2+ supported by an amido diphosphine pincer ligand features both a large fluoride ion affinity (FIA>SbF5 ) and hydride ion affinity (HIA>B(C6 F5 )3 ), which qualifies it as both a hard and soft LSA. The unusual Lewis acidic properties of [2]2+ are further showcased by its ability to abstract hydride and fluoride from Et3 SiH and AgSbF6 respectively, and effectively catalyze the hydrodefluorination, defluorination/arylation, as well as reduction of carbonyl compounds. One and two-electron reduction of [2]2+ affords stable boron radical cation [2]â
+ and borylene 2, respectively. The former species has an extremely high spin density of 0.798e at the boron atom, whereas the latter compound has been demonstrated to be a strong organic base (calcd. pKBH + (MeCN)=47.4) by both theoretical and experimental assessment. Overall, these results demonstrate the strong ability of geometric constraining to empower the central boron atom.
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Collection:
01-internacional
Database:
MEDLINE
Language:
En
Journal:
Angew Chem Int Ed Engl
Year:
2023
Document type:
Article
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