Comparing the experimental solution phase 1 H 𝛿 exp para to the calculated 𝛿 para results using either XRD or gasphase optimized structures, we find that the group 1 SiMe3 shifts have the incorrect sign and the group 2 SiMe3 shifts are under-predicted in magnitude by several ppm (see Supporting Information Tables ). As the solution pNMR data show local C3v point symmetry of the complex (borne out as a 1 : 2 ratio of the SiMe3 . Because the 𝛿 exp para are positive for the group 1 and negative for the group 2 1 H nuclei, and 𝜒 𝑧 -𝜒̅ is a constant common to both sets of 1 H environments, then the structural part