Study of packing of 4′-butyl-4-isothiocyanatotolane by X-ray diffraction and infrared spectra in polarized light

The packing properties of 4′-butylo-4-isothiocyanatotolane in the solid state and the liquid crystalline phases were studied by X-ray diffraction and infrared spectroscopy. The crystal structure comprises a herringbone-like packing with an efficient π–π overlap. The factors that shape the unusual broad νas(NCS) band are discussed. Selection of modes involved in the Fermi resonance interaction with the νas(NCS) vibration is supported by directions of their transition dipole moments obtained at the DFT calculations. A specific rearrangement in the herringbone packing, accompanying transition from the solid state to the isotropic phase was confirmed by the dichroic ratio values.