Bulky monodentate ligands affect the structure and reactivity of siliconium ion complexes in several ways: they enhance ionization, they promote a methyl halide elimination reaction, and they severely distort complex geometries. The latter effect enabled the assembly of a reaction coordinate model for the Berry pseudorotation, composed of crystal structures with varying NSiN and OSiO bond angles. In a competition between opposing effects of electron withdrawal by CF3 and steric bulk of a cyclohexyl ligand in the same molecule, a nonionic dissociation of the dative N→Si bond was observed. © 2005 WILEY-VCH Verlag GmbH & Co. KGaA.