η5-Cyclopentadienyl derivatives of tin(II) studied by two-dimensional multinuclear magnetic resonance in solution and by 13C and 119Sn CP/MAS NMR in the solid state
✍ Scribed by Bernd Wrackmeyer; Ēriks Kupče; Gerald Kehr; Angelika Sebald
- Publisher
- John Wiley and Sons
- Year
- 1992
- Tongue
- English
- Weight
- 422 KB
- Volume
- 30
- Category
- Article
- ISSN
- 0749-1581
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✦ Synopsis
Abstract
Absolute coupling signs of ^1^J(^119^Sn, ^13^C) (2__J__(^119^Sn, ^1^H) (n^5^‐C~5~H~5~)~2~Sn (1) and ^1^J(^119^Sn, ^13^C) (2__J__(^119^Sn, ^13^C) (3__J__(^119^Sn, ^1^H) (>O) in (n^5^‐C~5~Me~5~)~2~Sn (2) were determined using advanced direct and indirect two‐dimensional methods. These are based on Ψ‐BIRD techniques and z‐filtering, leading to pseudotriple‐resonance experiments of the type ^1^H{^119^Sn(^13^C)} and ^13^C{^1^H(^119^Sn)}, respectively. A mixed n^5^‐cyclopentadienyltin(II) amide was prepared and characterized by ^1^H, ^13^C, ^29^Si and ^119^Sn NMR in solution in the presence of its symmetrical redistribution products 1 and [(Me~3~Si)~2~N]~2~Sn. Solid‐state ^119^Sn CP/MAS NMR spectra of 1 shows the presence of two tin sites (in accord with the x‐ray analysis) with a 62.2 ppm difference in ^119^Sn chemical shifts, the mean value being in close agreement with the solution‐state δ^119^Sn value. The symmetries of the shielding tensor for the two tin sites are different and there appears to be a correlation between this property and the ring centroid—Sn—ring centroid angle α. ^13^C CP/MAS NMR proved insensitive to the structural differences between the two types of molecules of 1 in the unit cell.