1 C6D6 : C4D8O solutions each show two trimethylsilyl environments in a 1 : 2 ratio, and for M = La and Ce we also observe two signals for SiMe3 groups in both the 13 C{ 1 H} and Si DEPT solution NMR spectra. We attribute this observation to restricted rotation of M-Si bonds on the NMR timescale upon loss of THF from coordination spheres;