Hyperconjugation between the CH2 Si bond and the charged pyridinium π system in the N- methyl 4-trimethylsilylmethyl pyridinium ion (8), manifests in the crystal structure as lengthening of the CH2 Si bond, shortening of the CH2 Cipso bond and smaller but systematic effects on the C C bond distances within the pyridinium ring. The structural effects are supported in solution by systematic effects on the 29Si–13C and 13C–13C one ...