Variable-temperature 13C CP/MAS study of (Me3Sn)2CO3

✍ Scribed by Jörg Kümmerlen; Angelika Sebald

• Publisher: John Wiley and Sons
• Year: 1994
• Tongue: English
• Weight: 499 KB
• Volume: 32
• Category: Article
• ISSN: 0749-1581
• DOI: 10.1002/mrc.1260320306

✦ Synopsis

Abstract

Solid (Me~3~Sn)~2~CO~3~, 1, forms polymeric zig‐zag chains were bidentate magnified image units (containing a tetrahedral Me~3~Sn group) connect trigonal‐bipyramidal Me~3~SnO~2~ units which form the polymeric backbone. Both the tetrahedral and the trigonal‐bipyramidal Me~3~Sn moiety in solid 1 undergo 2π/3 reorientation around their respective SnO bonds at ambient temperature. Although ^13^C cross‐polarization magic angle spinning (CP/MAS) spectra of 1 are strongly temperature dependent in the temperature range 160–383 K, neither lineshape analysis of these exchange‐broadened ^13^C spectra nor ^13^C 2D exchange spectroscopy allows the extraction of meaningful kinetic data for solid 1. Owing to severe overlap problems in the various ^13^C CP/MAS spectra and because of the apparent vastly different 2π/3 jump rates for the two different Me~3~Sn units in solid 1, only combined information from variable‐temperature/variable‐r.f. irradiation strength ^13^C CP/MAS experiments in conjunction with consideration of geometric information from single‐crystal x‐ray diffraction yields an estimate of the respective activation energies for the 2π/3 jump processes of the trigonal‐bipyramidal Me~3~Sn(1) unit (E~a~ = 22.1 ± 2.4 kJ mol^−1^) and of the tetrahedral Me~3~Sn(2) unit (E~a~ ≈︁ 50 kJ mol^−1^) in solid 1.