A series of homologues of the trityl cation obtained by total or partial substitution of the phenyl ring8 for 2-or 3-thienyl groups has been studied by 1H and 18C NMR. In general, the spectral parametera found follow the expected trends. However, a moat unexpected effect is found in the transformation of tris (2-thieny1) carbinol (la) into tris (24hienyl) methyl cation (2d), since the increase of the total chemical shift (Azfi) associated with the ionization is as ...
