Secondary bonding in para-substituted diphenyltellurium dichlorides (p-XC6H4)2TeCl2 (X=H, Me, MeO) probed by 125Te MAS NMR spectroscopy. Crystal and molecular structure of (p-MeC6H4)2TeCl2

The solid-state structures of the previously known para-substituted diphenyltellurium dichlorides, (p-XC6H4)2TeCl2 (X=H (1), Me (2), MeO (3)) were investigated by 125Te MAS NMR spectroscopy and in case of 2 by single crystal X-ray diffraction. The 125Te-NMR shielding anisotropy (SA) was studied by tensor analyses based on relative intensities of the observed spinning sidebands. Solid-state NMR parameters, namely the isotropic chemical shift (δiso), anisotropy (ζ) and asymmetry (η), were discussed in relation to the molecular structures established by X-ray crystallography. The asymmetry (η) was found to be particularly sensitive to structural differences stemming mostly from the diverse secondary Te⋯Cl interactions, but no correlation with geometric parameters could be established.