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Synthesis of the Soft Lewis Superacid Tris(4‐bromo‐2,3,5,6‐tetrafluorophenyl)borane B(C 6 F 4 Br) 3 via C‒Ag to C‒B Transmetalation

Year: 2025

Type: article

Abstract: The Lewis acid tris(4‐bromo‐2,3,5,6‐tetrafluorophenyl)borane B(C 6 F 4 Br) 3 was synthesized via transmetalation from BBr 3 and AgC 6 F 4 Br. The latter was prepared from 1,4‐C 6 F 4 BrSiMe 3 with AgF and crystallized as a toluene solvate [2(AgC 6 F 4 Br) 4 •7.46(toluene)]. The solid‐state structure of free B(C 6 F 4 Br) 3 and its Lewis base adducts with EtCN, H 2 O, and POEt 3 was determined by single‐crystal X‐ray diffraction. DFT calculations show that B(C 6 F 4 Br) 3 has approximately 1% higher fluoride and hydride ion affinities (FIA and HIA) than tris(pentafluorophenyl)borane B(C 6 F 5 ) 3 . Similarly, the Gutmann‐Beckett method indicates an increase in Lewis acidity of 2%, whereas IR spectroscopy of the CD 3 CN adducts reveals a slightly lower ṽ(CN) vibration for B(C 6 F 4 Br) 3 . The presence of bromine atoms is expected to facilitate structural analysis of Lewis acid‐base adducts of B(C 6 F 4 Br) 3 by single‐crystal X‐ray diffraction in the future.

Source: Chemistry - A European Journal

DOI: 10.1002/chem.202502240

Authors: Amina L. Moshtaha, Erika M. Peter, Robin Sievers, Tim‐Niclas Streit, Moritz Malischewski

Institution: Freie Universität Berlin

Language: English

Topic: Organoboron and organosilicon chemistry

Subfield: Organic Chemistry

Field: Chemistry

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $4,640

Funders: Fonds der Chemischen Industrie, Deutsche Forschungsgemeinschaft, Freie Universität Berlin