The X-ray crystal structures ofE-N, N-dimethyl-3-phenyl-2-propenylideniminium perchlorate,1, andE-N, N-dimethyl-3-(p-methoxyphenyl)-2-propenylideniminium perchlorate,2, have been determined.E-N,N-dimethyl-3-phenyl-2-propenylideniminium perchlorate, (C11H14N+)(ClO4−),1, is orthorhombic:Pmcn (No. 62)a=6.595(1),b=18,288(4),c=10.216(2) Å,Z=4.E-N, N-dimethyl-3-(p-methoxyphenyl)-2-propenylideniminium perchlorate, (C12H16NO+)(ClO4−),2, is triclinic:P1 (No. 2) with cell dimensionsa=6.862(1),b=9.830(2),c=13.376(3) Å,α=119.05(1),β=114.99(2), γ=90.79(2)°, andZ=2. Data for both crystals were collected with the use of MoKα radiation and a Syntex P21 diffractometer. The crystal structures were solved by standard methods and refined toR1=0.0688,R2=0.0772 for1 andR1=0.0790 andR2=0.0757 for 2 based on 869 and 1765 independent reflections, respectively. The bond distances are consistent with a highly localized structure with the positive charge situated principally in the iminium moiety. The13C NMR spectra of these salts were obtained on the crystalline solids by CPMAS methods. Since the13C chemical shifts of the salts were very similar, in both solution and solid states, it was concluded that the structures of the salts were comparable in both phases and were analogous.