solution of 1-La at room temperature (ΔSiMe3 = 7.8 ppm) is close to the mean (ΔSiMe3 = 8.1 ppm) of equivalent differences calculated for 1-La (ΔSiMe3 = 9.9 ppm; δiso = -2.6 and 7.3 ppm) and its M(THF)1 analogue (ΔSiMe3 = 6.3 ppm; δiso = -2.1 and 4.2 ppm). These data are in accord with 1-La forming a dynamic equilibrium with the desolvated La(THF)1 form and deuterated analogues in the solution NMR experiments. We therefore posit that the presence of two signals for SiMe3 groups in solutions of 1-M is due to restricted rotation of the M-Si bonds, likely due to the desolvated species showing stronger interactions of coordinatively unsaturated M(III) ions with hypersilanide ligands and the resultant metal coordination spheres being more congested, consistent with the optimized gas-phase geometries.