Centrohexaindane, a Unique Polyaromatic Hydrocarbon Bearing the Rare C^q (C^q )₄ Core: Inelastic Neutron Scattering,...

Area of Science:

• Organic Chemistry
• Solid-State Chemistry
• Spectroscopy

Background:

• Centrohexaindane possesses a unique core structure with a central quaternary carbon atom bonded to four other quaternary carbons.
• Previous Nuclear Magnetic Resonance (NMR) studies suggested a high degree of symmetry (tetrahedral, Td) for this molecule in solution.

Purpose of the Study:

• To investigate the solid-state and solution-state structure and vibrational spectroscopy of centrohexaindane.
• To reconcile the observed symmetry in different states using spectroscopic and crystallographic data.

Main Methods:

• Infrared (IR) and Raman spectroscopy were employed for vibrational analysis in solution.
• X-ray powder diffraction was used to determine the unit cell characteristics in the solid state.

Main Results:

• Solution vibrational spectra (IR and Raman) of centrohexaindane are consistent with tetrahedral (Td) symmetry.
• Solid-state X-ray powder diffraction indicates a complex unit cell (triclinic or monoclinic) with a large volume (>4000 ų).
• Solid-state vibrational spectroscopy suggests lower site symmetry (C1) and the presence of at least two molecules per primitive cell, likely in a centrosymmetric space group.

Conclusions:

• The symmetry of centrohexaindane differs significantly between solution and solid states.
• Vibrational spectroscopy and X-ray diffraction provide complementary insights into the molecular and crystal structure of centrohexaindane.