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Variable‐temperature 13 C CP/MAS study of (Me 3 Sn) 2 CO 3
Author(s) -
Kümmerlen Jörg,
Sebald Angelika
Publication year - 1994
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1260320306
Subject(s) - chemistry , crystallography , trigonal bipyramidal molecular geometry , magic angle spinning , atmospheric temperature range , spectral line , moiety , solid solution , crystal structure , nuclear magnetic resonance spectroscopy , stereochemistry , physics , organic chemistry , astronomy , meteorology
Solid (Me 3 Sn) 2 CO 3 , 1, forms polymeric zig‐zag chains were bidentateunits (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 SnO 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.