EFFECT OF MOLECULAR AND CRYSTAL-STRUCTURE OF N-NAPHTHYLURETHANES (CARBAMATES) ON THEIR IR-SPECTRA

A comparative analysis of the IR spectra in the region of 3000-400 cm( -1) of four urethanes (methyl-(N-(1-naphthyl) carbamate, ethyl-N-(1-na phthyl) carbamate, dimethyl-N,N'-(1,5-naphthylene) dicarbamate, and di ethyl-N,N'-(1,5-naphthylene) dicarbamate) with known molecular and cry stal structures was carried out. The assignment of the bands related t o the vibrations of the urethane and naphthyl fragments was refined on the basis of the study of the crystalline samples, melts, solutions, and deuterated analogs. The effect of the degree of conjugation of the urethane group with the naphthalene ring on the Amide II vibration fr equency in the crystals was shown. It was suggested that the stretchin g vibrations of the C(Ar)-N bond in naphthylurethanes (unlike aliphati c derivatives) make a considerable contribution to the Amide II vibrat ion, while the planar deformation vibration of the N-H bond was proved to be more significant for Amide III than for Amide II. In addition, strong nonspecific intermolecular interactions in the crystal can weak en valent bonds.