For each of the signals I-VI, a slice extracted from the aMAT spectra was fitted to determine the parameters of the shift tensor (isotropic shift δ, shift anisotropy ∆δ and asymmetry parameter η) (Fig. ). For each of the three nuclei, within each pair one signal (II, IV and V) possesses a larger isotropic shift and shift anisotropy compared to the second (I, III and VI). We can tentatively assign the former set of three signals to the same SiMe 3 group, and the latter set of signals to the other SiMe 3 group. This interpretation is supported by a transferred-echo double resonance (TEDOR) experiment (Fig. ), which displays a first unambiguous correlation between I and III, a second unambiguous correlation between II and IV, and no other correlations. These solid-state NMR spectra and our tentative interpretation indicate that each group of 1 H, Therefore, we suggest that the observed signals are consistent with the presence of the two distinct types of SiMe 3 groups, associated with Si 1 and Si 2 nuclei. Note that the span (Ω = δ 11δ 33 ) of Si 1 is Ω(Si 1 ) = 676 ppm, and the span of Si 2 is Ω(Si 2 ) = 479 ppm. These values are significantly larger than those previously obtained for Lu[CH(SiMe 3 ) 2 ] 3 (Ω(Si 1 ) = 46.8 ppm, Ω(Si 2 = 30.2 ppm), which is expected because that compound is diamagnetic. The pattern, observed for Lu[CH(SiMe 3 ) 2 ] 3 , was the strongest experimental evidence that, combined with the DFT interpretations, showed that Si 1 was interacting with Lu through a Lu-Me-Si 3c-2e interaction. Although the Ω values for Yb[CH(SiMe 3 ) 2 ] 3 are significantly larger, a similar pattern emerges; Si 1 has a larger Ω(Si) than Si 2 , suggesting that Si 1 is also interacting with Yb to form a 2c-2e Yb-Me-Si.