Experimental and computational studies of the structure and vibrational spectra of 2-[5,5-dimethyl-3-(2-phenyl-vinil)-cyclohex-2-enylidene]-malononitrile.

The FTIR spectra (4000-100 cm(-1)) and Raman spectra (3500-30 cm(-1)) of 2-[5,5-dimethyl-3-(2-phenyl-vinil)-cyclohex-2-enylidene]-malononitrile in solid state were measured. In addition, the structure and harmonic vibrational frequencies of this molecule were theoretically evaluated using B3LYP density functional methods. The computed vibrational frequencies are used to determine the types of molecular motions associated with each of the experimental bands observed. Bond length alternation (BLA) was established. Comparison with the experimental spectra provides important information about the ability of this computational method to describe the vibrational modes in this type of "push-pull" systems with potential non-linear optical applications.