C-13 NMR RELAXATION IN NEUTRAL AND CHARGED TETRA-N-ALKYL COMPOUNDS

NMR T-1 relaxation times have been measured for C-13 nuclei in the alk yl chains of symmetric tetra-n-alkylstannanes dissolved in CDCl3. The results are interpreted in terms of conformational transitions occurri ng in the aliphatic chains superimposed to rotational diffusion of the whole molecule. A comparison with analogous tetra-n-alkylammonium sal ts is performed. Differences are ascribed to changes in the overall ro tational diffusion deriving from effects of charge upon formation of i on-pairs and larger aggregates. (C) 1998 Elsevier Science B.V. All rig hts reserved.