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Comparative analysis of 13 C shielding constants stereospecificity in the silicon and germanium derivatives of acetylenic aldehyde and ketone oximes based on the 13 C NMR spectroscopy and GIAO calculations
Author(s) -
Afonin Andrei V.,
Pavlov Dmitry V.,
Mareev Alexander V.,
Simonenko Dmitry E.,
Ushakov Igor A.
Publication year - 2009
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.2435
Subject(s) - chemistry , ketone , aldehyde , chemical shift , double bond , nuclear magnetic resonance spectroscopy , germanium , carbon 13 nmr , medicinal chemistry , silicon , stereochemistry , organic chemistry , catalysis
In the acetylenic aldehyde oximes with substituents containing silicon and germanium, the 13 C NMR signal of the C‐2 carbon of triple bond is shifted by 3.5 ppm to lower frequency and that of the C‐3 carbon is moved by 7 ppm to higher frequency on going from E to Z isomer. A greater low‐frequency effect of 5.5 ppm on the C‐2 carbon signal and a greater high‐frequency effect of 11 ppm on the C‐3 carbon signal are observed in the analogous acetylenic ketone oximes. The carbon chemical shift of the CN bond is larger by 4 ppm in E isomer relative to Z isomer for the aldehyde and ketone oximes. The 29 Si chemical shifts in the silicon containing acetylenic aldehyde and ketone oximes are almost the same for the diverse isomers. The trends in changes of the measured chemical shifts are well reproduced by the gauge‐including atomic orbital (GIAO) calculations of the 13 C and 29 Si shielding constants. Copyright © 2009 John Wiley & Sons, Ltd.