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Generation and EPR Spectroscopy of the First Silenyl Radicals, R 2 C=Si . −R: Experiment and Theory
Author(s) -
Pinchuk Daniel,
Kratish Yosi,
Mathew Jomon,
Zborovsky Lieby,
BravoZhivotovskii Dmitry,
Tumanskii Boris,
Apeloig Yitzhak
Publication year - 2019
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201901772
Subject(s) - electron paramagnetic resonance , radical , unpaired electron , spectroscopy , hyperfine structure , hyperfine coupling , chemistry , bent molecular geometry , crystallography , resonance (particle physics) , nuclear magnetic resonance , atomic physics , materials science , physics , organic chemistry , quantum mechanics
The first two persistent silenyl radicals (R 2 C=Si . −R), with a half‐life ( t 1/2 ) of about 30 min, were generated and characterized by electron paramagnetic resonance (EPR) spectroscopy. The large hyperfine coupling constants (hfccs) ( a ( 29 Si α )=137.5–148.0 G) indicate that the unpaired electron has substantial s character. DFT calculations, which are in good agreement with the experimentally observed hfccs, predict a strongly bent structure (∡C=Si−R=134.7–140.7°). In contrast, the analogous vinyl radical, R 2 C=C . −R ( t 1/2 ≈3 h), exhibits a small hfcc ( a ( 13 C α )=26.6 G) and has a nearly linear geometry (∡C=C−R=168.7°).