Theoretical confirmation of the experimental Raman spectra of the lower-order diamondoid molecule: cyclohexamantane (C26H30)

The lower-order diamondoid hydrocarbon molecule, cyclohexamantane (C26H30), has been recently isolated from distilled Gulf Coast petroleum. While the structure of C26H30 has been confirmed through X-ray diffraction, mass spectroscopy, and 1H/13C NMR spectroscopy, its vibrational Raman spectra has only been identified through an indirect comparison with the experimental Raman spectra for adamantane and diamond. We used density-functional theory (DFT) to calculate a Raman spectra whose frequencies and relative intensities are in excellent agreement with the experimental Raman spectra for C26H30, thus providing direct vibrational proof of its existence.