Structure and wavelength modification in retinylidene iminium salts

The spectroscopic and structural properties of the perchlorate and triflate salts of N-n-butyl-retinylidene imine, 2 and 3, have been examined in solution and solid phases. In solution these salts were found to exhibit very similar UV and NMR spectroscopic properties. However, in the solid state marked differences in their absorption spectra (2, λ max = 504 nm; 3, λ max = 445 nm) and 13 C NMR spectra were found. The structures of the two salts …