Molecular symmetry and shielding tensor properties—some illustrative examples

Abstract 13C, 29Si, 119Sn and 207Pb cross‐polarization magic angle spinning (CP/MAS) spectra for a series of closely related compounds R4−nM(CCR′)n, (n = 1−4; M = Si, Sn, Pb; R = alkyl; R′ = alkyl, SiMe3) are reported. Shielding tensor components for 29Si, 119Sn and 207Pb as obtained from CP/MAS spectra are discussed in relation to the respective highest possible molecular symmetry group as a function of the degree of substitution n = 1−4. For this class of compounds the orientation of the shielding tensor of M within the molecular frame can sometimes be derived from symmetry considerations. The limitations of such considerations, based on shielding tensor components obtained from polycrystalline powder samples under CP/MAS conditions, are discussed.