Nuclear magnetic resonance investigations of carbonium ion intermediates. Part III. A chlorine-35 quadrupole resonance study of several (R-chloromethylene)dimethylammonium salts (Vilsmeier–Haack and Viehe reagents)

The 35Cl n.q.r. frequencies observed in a series of solid chloromethylenedimethylammonium salts are in agreement with the general structure (i). The variations in the C–35Cl resonance frequency indicate a large polarisability [graphic omitted] of the [NC]+ group, both with respect to the σ and π electron systems. The charge on the Cl atom increases in the order R = Cl < Ph < Pri < H.