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17 O and 31 P NMR of aroylphosphanes, aroylsilanes and aroylphosphonates: Absence of resonance in —COPR 2 groups (NMR of terminal oxygen, part 5 )
Author(s) -
Dahn Hans,
Péchy Peter,
Van Toan Vien
Publication year - 1990
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/mrc.1260281010
Subject(s) - chemistry , substituent , oxygen , aryl , ring (chemistry) , resonance (particle physics) , carbon 13 nmr , fluorine 19 nmr , stereochemistry , nmr spectra database , nuclear magnetic resonance spectroscopy , crystallography , medicinal chemistry , spectral line , organic chemistry , alkyl , physics , particle physics , astronomy
The 17 O NMR spectra for aryl‐substituted P , P ‐diphenylbenzoylphosphanes ( p ‐YC 6 H 4 COPPh 2 , 1), trimethylbenzoylsilanes ( p ‐YC 6 H 4 COSiMe 3 , 2) and dialkyl benzoylphosphonates ( p ‐YC 6 H 4 COPO(OR) 2 , 3) were recorded. Compounds 1, 2 and 3 show a similar high substituent sensitivity ( p + ), indicating a strong electron demand of the carbonyl group; as resonance stabilization is not possible in 2 and 3 it is concluded that electron donation from P to carbonyl is equally negligible in 1. The carbonyl oxygen signals of 1, 3 and, in particular, 2 appear at low field. The 31 P NMR shifts of 1 were also measured; they are less sensitive to the ring substituents.