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Isotope‐induced chemical shifts 2 Δ 10/11 B( 29 Si) in alkenylsilanes containing three‐ and four‐coordinate boron. A new tool for studying weak intramolecular boron–element bonds
Author(s) -
Wrackmeyer Bernd,
Tok Oleg L.
Publication year - 2002
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.1036
Subject(s) - chemistry , boron , intramolecular force , chemical shift , crystallography , isotopes of boron , silylation , chemical bond , stereochemistry , organic chemistry , catalysis
Numerous alkenylsilanes with silyl and boryl groups in cis ‐positions at the CC bond were studied for the first time by 29 Si NMR with regard to isotope‐induced chemical shifts Δ 10/11 B( 29 Si). Such effects are transmitted across an Si—X—B bridge (X = H, OR, SR, Cl) most efficiently if the interactions in this bridge are weak. In the absence of an Si—X—B bridge, 3 Δ 10/11 B( 29 Si) effects were not observed. In such cases, where, depending on the substituents, both weak and strong B—X bonding are possible, the 2 Δ 10/11 B( 29 Si) effects were readily observed only for weak B—X interactions (except for X = Cl), whereas for strong B—X bonding the effects were small or not detectable. Thus, the 2 Δ 10/11 B( 29 Si) values provide another tool for probing weak interactions which are not clearly reflected by other NMR data. Copyright © 2002 John Wiley & Sons, Ltd.