326-18-1Relevant articles and documents
Through-space 19F-19F spin-spin coupling in ortho-fluoro Z -azobenzene
Rastogi, Shiva K.,Rogers, Robert A.,Shi, Justin,Brown, Christopher T.,Salinas, Cindy,Martin, Katherine M.,Armitage, Jacob,Dorsey, Christopher,Chun, Gao,Rinaldi, Peter,Brittain, William J.
, p. 126 - 131 (2016)
We report through-space (TS) 19F-19F coupling for ortho-fluoro-substituted Z-azobenzenes. The magnitude of the TS-coupling constant (TSJFF) ranged from 2.2-5.9 Hz. Using empirical formulas reported in the literature, these coupling constants correspond to non-bonded F-F distances (dFF) of 3.0-3.5 ?. These non-bonded distances are significantly smaller than those determined by X-ray crystallography or density functional theory, which argues that simple models of 19F-19F TS spin-spin coupling solely based dFF are not applicable. 1H, 13C and 19F data are reported for both the E and Z isomers of ten fluorinated azobenzenes. Density functional theory [B3YLP/6-311++G(d,p)] was used to calculate 19F chemical shifts, and the calculated values deviated 0.3-10.0 ppm compared with experimental values.
