Information Figure ). The isotropic shift of the metal-bound silicon resonance in the Si MAS NMR spectrum, δiso- resonances in the expected region attributed to minor diamagnetic impurities in the sample including HSi(SiMe3)3 and another signal at -82 ppm that could not be identified. As the relaxation rate that causes paramagnetic broadening is ∝ These shifts essentially arise from a large deshielding of the δ11 component of the Si chemical shift tensor (see Table ), as the δ22 and δ33 components typically display negligible change (except for 1-Nd and 1-U). This infers a large anisotropy of the Si chemical shielding of the SiMe3 moieties and thus asymmetry of the electron distribution along the Si-Si bond, which is influenced by the f-block ion. For 1-Ln the magnitude of the deshielding of the δ11 component is inversely proportional to the apparent ionic radius (taken from the M-Si bond distance, Table ) of the f-ion (i.e.