Indirect nuclear spin-spin coupling constants in 1,2-diboretane-3-ylidene, a homoaromatic system with pi and sigma 3c/2e bonds. Comparison of experimental data with calculations using density functional theory (DFT) |
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Authors: | Wrackmeyer Bernd Berndt Armin |
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Affiliation: | Anorganische Chemie II, Universit?t Bayreuth, D-95440 Bayreuth, Germany. b.wrack@uni-bayreuth.de |
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Abstract: | The non-classical 1,2-diboretane-3-ylidene 1a was studied by 13C and 29Si NMR spectroscopy in order to obtain coupling constants 1J(13C,11B) and 1J(29Si,13C). The magnitudes of 1J(13C,11B) were deduced from linewidth measurements in low-temperature 13C and 11B NMR spectra. Calculation of the coupling constants for model compounds related to 1a, using DFT methods based on optimized geometries [B3LYP/6-311+G(d,p)], gave data in agreement with the experiments. Furthermore, the calculations predict for the first time a negative sign of 1J(13C,11B) which mirrors the bonding situation in 1 as described by theory. |
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Keywords: | NMR 11B NMR 13C NMR 29Si NMR coupling constants relative signs MO calculations organoboron compounds |
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