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|a pubmed25n0540.xml
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|a (DE-627)NLM161890849
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|a (NLM)16602078
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|a DE-627
|b ger
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|e rakwb
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|a eng
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|a Sýkora, Jan
|e verfasserin
|4 aut
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|a 29Si-13C spin-spin couplings over Si-O-Carom link
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|c 2006
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|a Text
|b txt
|2 rdacontent
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|a ohne Hilfsmittel zu benutzen
|b n
|2 rdamedia
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|a Band
|b nc
|2 rdacarrier
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|a Date Completed 30.07.2007
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|a Date Revised 07.06.2006
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|a published: Print
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|a Citation Status PubMed-not-MEDLINE
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|a Copyright (c) 2006 John Wiley & Sons, Ltd.
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|a 29Si-13C couplings were measured in para substituted silylated phenols, X--C6H4--O--SiR1R2R3 (X = NO2, CF3, Cl, F, H, CH3, CH3O). The SiR1R2R3 silyl groups included trimethylsilyl (Si(CH3)3, TMS), tert-butyldimethylsilyl (Si(CH3)2C(CH3)3, TBDMS), dimethylsilyl (SiH(CH3)2, DMS), and tert- butyldiphenylsilyl (Si(C6H5)2C(CH3)3, TBDPS). Previously developed (Si,C,Si)gHMQC methods and narrow 29Si lines allowed the determination of coupling constants over up to five bonds. Besides the number of intervening bonds between the silicon and carbon atoms, all the measurable couplings depend also on the nature of the substituents on the silicon. The two- and three-bond couplings are not affected by ring substitution in the para position. These properties render the 29Si-13C couplings suitable for line assignment in the spectra of silylated polyphenols. The experimental results are in reasonable agreement with theoretical calculations. The calculations show, in agreement with the data reported in the literature for couplings between other nuclei, that the two-bond and three-bond couplings, which are of similar magnitudes, are of opposite signs. If the signs of these geminal and vicinal couplings could be determined experimentally, they would greatly facilitate the line assignment. The four- and five-bond couplings are affected by the substituent X in a nontrivial manner
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|a Journal Article
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|a Blechta, Vratislav
|e verfasserin
|4 aut
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|a Sychrovský, Vladimír
|e verfasserin
|4 aut
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|a Hetflejs, Jirí
|e verfasserin
|4 aut
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|a Sabata, Stanislav
|e verfasserin
|4 aut
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|a Soukupová, Ludmila
|e verfasserin
|4 aut
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|a Schraml, Jan
|e verfasserin
|4 aut
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|i Enthalten in
|t Magnetic resonance in chemistry : MRC
|d 1985
|g 44(2006), 7 vom: 15. Juli, Seite 669-74
|w (DE-627)NLM098179667
|x 0749-1581
|7 nnns
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| 773 |
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|g volume:44
|g year:2006
|g number:7
|g day:15
|g month:07
|g pages:669-74
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|d 44
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|e 7
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|h 669-74
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