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13 C, 19 F and 77 Se NMR study of vicinal ( E )‐fluoro(organylseleno)olefins and [( E )‐fluoroalkenyl]diorganylselenonium salts
Author(s) -
Poleschner Helmut,
Heydenreich Matthias,
Radeglia Reiner
Publication year - 1999
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/(sici)1097-458x(199905)37:5<333::aid-mrc456>3.0.co;2-6
Subject(s) - chemistry , vicinal , fluorine 19 nmr , chemical shift , moiety , carbon 13 nmr , coupling constant , stereochemistry , nmr spectra database , crystallography , nuclear magnetic resonance spectroscopy , spectral line , organic chemistry , physics , particle physics , astronomy
13 C, 19 F and 77 Se NMR spectra of the ( E )‐fluoro(organylseleno)olefins R 1 (F)C α C β R 2 (SeR 3 ) and the [( E )‐fluoroalkenyl]diorganylselenonium salts R 1 (F)C α C β R 2 (Se + R 3 R 4 ) X − were measured and assigned. The 13 C, 19 F and 77 Se NMR chemical shifts, the 1 J F,C and 2 J F,C−β couplings, the vicinal 3 J Se,F couplings, some selected 13 C, 13 C and 77 Se, 13 C couplings and the 19 F, 13 C couplings to the groups R 1 – R 4 are discussed in relation to the structure of the compounds investigated. 1 J F,C increases with deshielding of the 13 C‐α atoms of the fluoro(organylseleno)olefins and the fluoroalkenyldiorganylselenonium salts, i.e. both quantities are influenced by the same electronic effects. Linear Hammett correlations of para ‐substituted phenylseleno derivatives (R=MeO, Me, Ph, H, Cl, COOH, COOEt, CN; R 1 =R 2 =Et) between δ( 13 C‐α), δ( 13 C‐β), δ( 19 F), δ( 77 Se) and 3 J Se,F , respectively, and σ p values, and linear correlations between the experimental quantities δ( 77 Se)/δ( 19 F), δ( 77 Se)/ 3 J Se,F and δ( 19 F)/ 3 J Se,F (each with a positive slope) show that close relations exist (i) between the NMR chemical shifts within the FCCSe moiety and (ii) between the NMR chemical shifts ( 77 Se, 19 F) and the couplings 3 J Se,F by alteration of the electron density in this structural element. The vicinal 3 J Se,F coupling constant across the CC double bond ( trans ‐coupling) is sensitive to structural alterations (<1 to 68.5 Hz). In the case of 1,1‐difluorovinylphenyl selenide, F 2 CCHSePh, the 3 J Se,F coupling constants obey the relation 3 J trans > 3 J cis (40.8, 3.2 Hz). Copyright © 1999 John Wiley & Sons, Ltd.