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Molecular Bismuth Cations: Assessment of Soft Lewis Acidity
Author(s) -
Ramler Jacqueline,
Lichtenberg Crispin
Publication year - 2020
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202001674
Subject(s) - lewis acids and bases , cationic polymerization , bismuth , heteronuclear molecule , chemistry , substituent , halide , crystallography , stereochemistry , nuclear magnetic resonance spectroscopy , polymer chemistry , organic chemistry , catalysis
Three‐coordinate cationic bismuth compounds [Bi(diaryl)(EPMe 3 )][SbF 6 ] have been isolated and fully characterized (diaryl=[(C 6 H 4 ) 2 C 2 H 2 ] 2− , E=S, Se). They represent rare examples of molecular complexes with Bi⋅⋅⋅EPR 3 interactions (R=monoanionic substituent). The 31 P NMR chemical shift of EPMe 3 has been found to be sensitive to the formation of LA⋅⋅⋅EPMe 3 Lewis acid/base interactions (LA=Lewis acid). This corresponds to a modification of the Gutmann–Beckett method and reveals information about the hardness/softness of the Lewis acid under investigation. A series of organobismuth compounds, bismuth halides, and cationic bismuth species have been investigated with this approach and compared to traditional group 13 and cationic group 14 Lewis acids. Especially cationic bismuth species have been shown to be potent soft Lewis acids that may prefer Lewis pair formation with a soft (S/Se‐based) rather than a hard (O/N‐based) donor. Analytical techniques applied in this work include (heteronuclear) NMR spectroscopy, single‐crystal X‐ray diffraction analysis, and DFT calculations.