Substituent Effects on 31P and 13C Chemical Shifts of Substituted Diphenyl 1-anilino-1-arylmethanephosphonates and Their Anions |
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| Authors: | Scott Smith Hans Zimmer Eckehard Fluck Peter Fischer |
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| Institution: | 1. Department of Chemistry , University of Cincinnati , Ohio, 45.221, U.S.A.;2. Gmelin-Institut für Anorganische Chemie der Max-Planck-Gesellschaft , Varrentrappstra?e 40/42, D-6000, Frankfurt 90;3. Institut für Organische Chemie / Abteilung Spektroskopie, Universit?t Stuttgart , Pfaffenwaldring 55, D-7000, Stuttgart 80 |
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| Abstract: | Abstract For a series of 31 novel diphenyl 1-anilino-1-arylmethanephosphonates, substituted in the meta and para position of the anilino and/or the aryl ring, 31P chemical shifts show good linear correlation with Taft's sgrave]° parameters, the 31P nucleus appearing better shielded in the case of electron-withdrawing substituents. This inverse relationship is due to a field effect of the substituent dipole which polarizes π-electron clouds in the molecule, resulting in a higher P=O double bond order, and thence better 31P shielding. A corresponding shift of π-electron density is likewise observed for the 13C resonances of the two diastereotopic phenoxy and the anilino or aryl rings, respectively, where-M ands-I substituents cause a downfield shift of para and meta, and an upfield shift of ortho and ipso carbon resonances. |
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