Through-space (19)F-(19)F spin-spin coupling in ortho-fluoro Z-azobenzene.
We report through-space (TS) (19)F-(19)F coupling for ortho-fluoro-substituted Z-azobenzenes. The magnitude of the TS-coupling constant ((TS) JFF ) 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 Å. These non-bonded distances are significantly smaller than those determined by X-ray crystallography or density functional theory, which argues that simple models of (19)F-(19)F TS spin-spin coupling solely based dFF are not applicable. (1)H, (13)C and (19)F 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 (19) F chemical shifts, and the calculated values deviated 0.3-10.0 ppm compared with experimental values.
Department of Chemistry and Biochemistry, Texas State University, 601 University Drive, San Marcos, TX, 78666, United States.
Shiva K
SK
Rastogi
Department of Chemistry and Biochemistry, Texas State University, 601 University Drive, San Marcos, TX, 78666, United States.
Robert A
RA
Rogers
Department of Chemistry and Biochemistry, Texas State University, 601 University Drive, San Marcos, TX, 78666, United States.
Justin
J
Shi
Department of Chemistry and Biochemistry, Texas State University, 601 University Drive, San Marcos, TX, 78666, United States.
Christopher T
CT
Brown
Department of Chemistry and Biochemistry, Texas State University, 601 University Drive, San Marcos, TX, 78666, United States.
Cindy
C
Salinas
Department of Chemistry and Biochemistry, Texas State University, 601 University Drive, San Marcos, TX, 78666, United States.
Katherine M
KM
Martin
Department of Chemistry and Biochemistry, Texas State University, 601 University Drive, San Marcos, TX, 78666, United States.
Jacob
J
Armitage
Department of Chemistry and Biochemistry, Texas State University, 601 University Drive, San Marcos, TX, 78666, United States.
Christopher
C
Dorsey
Department of Chemistry, The University of Akron, Akron, OH, 44325, United States.
Gao
G
Chun
Department of Chemistry, The University of Akron, Akron, OH, 44325, United States.
Peter
P
Rinaldi
Department of Chemistry and Biochemistry, Texas State University, 601 University Drive, San Marcos, TX, 78666, United States.
William J
WJ
Brittain
13C; 19F; 1H; NMR; azobenzene; cis-azoenzene; fluorinated azobenzene; through-space coupling