(C═C═C═C)@C60: A Bonding C60-Endohedral Molecular Allotrope of Carbon

The allotropes of carbon have been the focus of attention in recent years. In this work, we reported a molecular allotrope of carbon, C60-endohedral: (C=C=C=C)@C60. The smallest vibrational frequency is 226.0 cm-1, which confirms that (C=C=C=C)@C60 is a minimum on the potential energy hypersurface. Its geometry, NMR diagram, IR spectrum, heat of formation, and bonding interactions have been predicted using the density functional theory (DFT) method at the B3LYP/6-311G(d) level of theory. Since there must be a large family of the fullerene-endohedral allotropes of carbon, the research studies on these allotropes of carbon will open an avenue for allotropes of carbon.