The structures of some iminium salts. Crystal structures and13C NMR studies of 3-aryl-2-propenylideniminium salts

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,=119.05(1),=114.99(2), =90.79(2)°, andZ=2. Data for both crystals were collected with the use of MoK 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 the^13C 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.