Stability and structure of oligomers and polymers made of xenon and hydrocarbons: Theoretical predictions

Calculations at B3LYP level predict the existence of three carbon chain oligomers containing HXeCC branches: C7 H8 Xe2, C11 H12 Xe3, and C15 H16 Xe4. The geometries and NBO charges of the HXeCC groups in the species are similar to those of the experimental known HXeCCH molecule, and are insensitive to the length of the carbon chain. The structures of the xenon oligomers are very similar to their hydrocarbon precursors. The energetics for C11 H12 Xe3 is calculated to assess the stability of these polymers. Similar to HXeCCH, C11 H12 Xe3 is kinetically stable and protected by a high barrier of 2.47 eV against dissociation to C11 H12 Xe2 +Xe, and is energetically more stable by 1.30 eV than the C11 H11 Xe2 +Xe+H products, which strongly supports the existence of the molecule. Extrapolation of the results for the oligomers suggests the existence of an extended [- CH2 CH(CCXeH)-] n polymer. A strategy for preparation is proposed.