N-Triorganostannyl-substituted pyrroles and indoles and N-trimethylstannylcarbazole: determination of signs of coupling constants and isotope-induced chemical shifts 1Δ14/15N(119Sn)
✍ Scribed by Bernd Wrackmeyer; Gerald Kehr; Heidi E. Maisel; Hong Zhou
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 325 KB
- Volume
- 36
- Category
- Article
- ISSN
- 0749-1581
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✦ Synopsis
N-Triorganostannyl pyrroles (1) and indoles (2) [R \ Me (a), Et (b), tBu (c)], N-(R
Sn)-substituted trimethylstannyl-carbazole (3), N-trimethylstannyl-2,5-dimethylpyrrole (1d), the corresponding silicon and lead derivatives [1d(Si) and 1d(Pb)] and N-trimethylstannyl-2-methylindole (2d) were prepared and studied by multinuclear magnetic resonance (1H, 13C, 15N, 29Si, 119Sn and 207Pb NMR). The absolute signs of numerous coupling constants nJ(119Sn,13C) and 1J(119Sn,15N) (\0) were determined by appropriate 2D heteronuclear shift correlations of the type 13C/1H and 15N/1H. Precise measurement of the coupling constants 1J(119Sn,15N) from 119Sn NMR spectra by using Hahn-echo extended (HEED) polarization transfer pulse sequences enabled one to obtain isotope-induced chemical shifts 1*14@15N(119Sn) at natural abundance of 15N. The 1*14@15N(119Sn) data become more negative with increased branching of the substituent R at the tin atom and with stronger steric interactions. The latter e †ect is also evident from d119Sn values and changes in the magnitude of the coupling constants 1J(119Sn,13C) or 1J(119Sn,15N).