Studying Natural Buckyballs and Buckybowls in Fossil Materials

Buckyballs (fullerenes) were first reported over 30 years ago, but still little is known regarding their natural occurrence, since they have so far only been found at sites of high‐energy incidents, such as lightning strikes or meteor impacts, but have not been reported in low‐energy materials like fossil fuels. Using ultrahigh‐resolution mass spectrometry, a wide range of fullerenes from C₃₀ to C₁₁₄ was detected in the asphaltene fraction of a heavy crude oil, together with their building blocks of C_10nH₁₀ stoichiometry. High‐level DLPNO‐CCSD(T) calculations corroborate their stability as spherical and hemispherical species. Interestingly, the maximum intensity of the fullerenes was found at C₄₀ instead of the major fullerene C₆₀. Hence, experimental evidence supported by calculations show the existence of not only buckyballs but also buckybowls as 3‐dimensional polyaromatic compounds in fossil materials.     

Some Properties of a Model Liquid of C 60 Buckyballs

Utilizing the results of published simulations for the liquid C 60 phase using a model of rigid C 60 molecules, it is pointed out that the liquid phase has a critical compressibility ratio Z c = p c /( c k B T c ) in terms of the usual critical thermodynamic variables (critical pressure p c , critical density c and critical temperature T c ), of 0.32. This is to be compared with the value 0.29 for the heavy condensed rare gases Ar, Kr and Xe, in spite of their much lower T c , and with the prediction of 0.27 from Dieterici's phenomenological equation of state. The global shape of the coexistence curve, as embodied in the behaviour of the normalized difference density ( l m g )/ c versus the average density ( l + g )/2 c , where l and g are the liquid and the gas densities, respectively, is also consistent with the shape of the coexistence curve of insulating fluids. Going beyond the assumption of rigid C 60 molecules has interesting consequences on the stability and observability of the liquid phase, and those effects are discussed.     

The Exact Icosahedral Symmetry Relations for Atomic Overlaps,Molecular Orbitals and Vibrational Species of C60 Buckyballs

A computer adapted vector method and Euler angle transformation procedures are used to generate the relationship between the atomic orbitals of icosahedral C₆₀ Buckminsterfullerene cluster and to produce symmetry adapted molecular orbitals and vibrational species. The atomic overlaps based on the orientational relationship of the orbitals are used to compute the approximate molecular orbital energies and normalization constants. One of the vibrations of A_u, symmetry is used to interpret the isomeric (dyotropic) rearrangement that breaks and forms two bonds to change two pentagons to two hexagons and vice versa.     

ChemInform Abstract: Prediction of the Intensity and Structure of Spectra Associated with the Endohedral motions of Metal-Containing Buckyballs.

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