Long-range tin-tin coupling constants: II. Two-bond coupling via carbon |
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Authors: | TN Mitchell A Amamria B Fabisch HG Kuivila TJ Karol K Swami |
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Institution: | Abteilung Chemie, Universität Dortmund, Postfach 500 500, 4600 Dortmund 50 F.R.G.;Department of Chemistry, State University of New York at Albany, Albany, NY 12222 U.S.A. |
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Abstract: | Tin-119 and carbon-13 NMR data for a total of 34 compounds containing the grouping Sn-C-Sn (C is either sp3- or sp2-hybridised) are presented and discussed. In organotin derivatives of alkanes, 2J(Sn-C-Sn) can only be correlated with 1J(Sn-C2) if a sign change for the former coupling is assumed. In most of the compounds of this type studied, 1J(Sn-CH3) is, due to rehybridisation and in contrast to the usual situation, larger than 1J(Sn-C2); the same is true in some cases for distannylakenes, the behaviour of which is complicated by changes in the torsional angle about the carbon-carbon double bond. Thus correlation of 2J(Sn-C-Sn) with other spectral parameters is not possible in these cases. The total tin chemical shift range for compounds MenSn(CH2MME3)4-n (M C, Si, Ge, Sn; n 0–4) is 140 ppm. Incorporation of a ditin fragment in a six-membered ring causes a downfield tin shift of 30 ppm. |
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