Magic-angle spinning NMR spectra and re-examined crystal structure of trimethyltin cyanide

The structure of crystalline trimethyltin cyanide has been studied by magic-angle spinning NMR, by DFT computations and by single-crystal X-ray diffraction. An earlier diffraction study reported some disorder in the Sn-C-N-Sn chains. However, the Sn-119 spectrum shows unequivocally that this is not so, since only a single centreband isotropic signal is observed. This finding is confirmed by DFT calculations, the results of which are consistent with an ordered C-N-Sn-C-N environment for tin. The computed shielding anisotropy is in good agreement with the experimental value obtained from spinning sideband analysis. Carbon-13 CPMAS data are also reported. A new synthetic procedure provided high-quality crystals, enabling X-ray diffraction to be applied with modern equipment. The results confirmed the conclusion made from the NMR experiments and the DFT computations. The chain structure is ordered, though positions of some hydrogen atoms may be disordered. Revised geometrical data are reported and discussed. (C) 2004 Elsevier SAS. All rights reserved.