Centrohexaindane, a Unique Polyaromatic Hydrocarbon Bearing the Rare Cq(Cq)4 Core: Inelastic Neutron Scattering, Infrared and Raman Spectroscopy.

The structure and vibrational spectroscopy of centrohexaindane, 1, was investigated. This unusual molecule has a quaternary carbon atom that is coordinated to four further such quaternary carbon atoms as its core, each pair of which is bonded to an ortho‐phenylene unit. Previous NMR studies have shown that the molecule has tetrahedral (Td) symmetry in solution. The infrared and Raman spectra of chloroform and deuterochloroform solutions of 1 are completely in agreement with this conclusion, as the only modes that are visible are those allowed for Td symmetry. This is not the case in the solid state: X‐ray powder diffraction indicates that the unit cell is triclinic or monoclinic with a volume in excess of 4000 Å3. The vibrational spectroscopy is consistent with C1 site symmetry and the presence of at least two molecules in the primitive cell. It is likely that the space group is centrosymmetric. [ABSTRACT FROM AUTHOR]