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1. List of Contributors

Author

Timothy M Alce, Sumesh Arora, Thearina de Beer, Rinaldo Bellomo, Andrew D Bersten, Tim Bowles, Jeremy P Campbell, Alastair C Carr, Marianne J Chapman, Kai Man Chan, Gordon YS Choi, Christine Chung, Jeremy Cohen, David Collins, D James Cooper, Evelyn Corner, Simon Cottam, Sarah Cox, Lester AH Critchley, Andrew R Davies, Anthony Delaney, Rishi H-P Dhillon, Tavey Dorofaeff, Graeme J Duke, Cyrus Edibam, Evan R Everest, Simon Finfer, Malcolm M Fisher, Oliver J Flower, Carole Foot, David Fraenkel, Steven T Galluccio, A Raffaele De Gaudio, Tony Gin, Charles D Gomersall, Anthony C Gordon, Munita Grover, Pascale Gruber, Anish Gupta, Jonathan M Handy, Sara Hanna, James Hatcher, Felicity H Hawker, Michelle Hayes, Victoria Heaviside, Liz Hickson, Alisa Higgins, Pierre Hoffmeyer, Andrew Holt, Matthew R Hooper, Li C Hsee, Nicholas Ioannou, James P Isbister, Matthias Jacob, Paul James, Paul Cassius Jansz, Mandy O Jones, Gavin M Joynt, James A Judson, Richard Keays, Angus M Kennedy, Ian Kerridge, Geoff Knight, Stephen W Lam, Richard Leonard, Daniel Lew, Alexander M Man Ying Li, Jeffrey Lipman, Pieter HW Lubbert, Peter S Macdonald, David P Mackie, Matthew Maiden, Colin McArthur, Kevin McCaffery, Steve McGloughlin, Johnny Millar, Wai Ka Ming, Fiona H Moffatt, Thomas J Morgan, Peter T Morley, John A Myburgh, Michael MG Mythen, Matthew T Naughton, Alistair D Nichol, Gerry O'Callaghan, Helen I Opdam, Aaisha Opel, Alexander A Padiglione, Simon PG Padley, Valerie Page, Mark Palazzo, Sandra L Peake, Vincent Pellegrino, Michael E Pelly, David Pilcher, Didier Pittet, Kevin Plumpton, Brad Power, Susanna Price, Raymond F Raper, Michael C Reade, Bernard Riley, Shelley D Riphagen, Hayley Robinson, Vineet V Sarode, Hugo Sax, Manoj K Saxena, Oliver R Segal, Frank Shann, Pratik Sinha, Ramachandran Sivakumar, George Skowronski, Anthony J Slater, Martin Smith, Neil Soni, Stephen J Streat, Richard Strickland, David J Sturgess, Christian P Subbe, Joseph JY Sung, Chee Wee Tan, Guido Tavazzi, Peter D (Toby) Thomas, James Tibballs, Luke E Torre, David Treacher, David V Tuxen, Ilker Uçkay, Balasubramanian Venkatesh, Jacqueline EHM Vet, Marcela P Vizcaychipi, Adrian J Wagstaff, Carl S Waldmann, Christopher M Ward, John R Welch, Julia Wendon, Mary White, Ubbo F Wiersema, Timothy Wigmore, Christopher Willars, Wan Tsz Pan Winnie, David M Wood, Duncan LA Wyncoll, and Steve M Yentis

Published
2014
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3. Through-space13C-19F couplings in highly-crowded systems: Radial dependence and electronic effects

Author

Li C. Hsee and D. J. Sardella

Subjects
Steric effects, Coupling, Stereochemistry, Substituent, General Chemistry, Nuclear magnetic resonance spectroscopy, Crystallography, chemistry.chemical_compound, chemistry, Electronic effect, Pyrene, Molecule, General Materials Science, Lone pair
Abstract

The helical molecule 1-fluorobenzo[ c] phenanthrene shows a large (17.4 Hz) 13C–19F coupling resulting primarily from direct through-space overlap between a fluorine lone pair and the sterically opposed CH bond. After application of corrections for estimated through-bond contributions, comparison of the magnitude of this coupling with the analogous couplings in 4-fluorophenanthrene, 10-fluorobenzo[ a] pyrene, 11-fluoro-5-methylchrysene and 7-fluorobenzo[b] fluoranthene reveals an exponential decrease with increasing H … F internuclear distance, consistent with theoretical predictions. No evidence was found for an angular dependence of the coupling. HETCOR experiments showed the signs of n+1J(HF) in 1-fluorobenzo[ c] phenanthrene, 4-fluorophenanthrene, 10-fluorobenzo[ a] pyrene and 11-fluoro-5-methylchrysene to be opposite to those of the corresponding nJ(CF), hence negative. Substituents at both positions 4 (para to fluorine) and 9 (para to the sterically opposed CH bond) exert only a minor influence on 5J(CF), the couplings in the latter series responding largely to sterically induced distortions of the molecular framework, and in the former series to both steric distortions and an electronic effect. The difference in 5J(CF) between isomers is a measure of the electronic effect of the substituent. Electron-withdrawing substituents para to fluorine reduce the magnitude of the through-space coupling whereas electron-releasing substituents increase the coupling.

Published
1990
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