New trends along hydrogen polyoxides: unusually long oxygen–oxygen bonds in H₂O₆ and H₂O₇

Abstract

By means of coupled cluster, G4 and B3LYP calculations, we characterised polyoxides H₂O₆ and H₂O₇. These two molecules behave very differently from lower polyoxides, given that some isomers present unusual bonding. In the case of H₂O₆, the central OO bond is predicted, to be 1.909 Å, at the CCSD(T)/cc-pVTZ level. Two conformational isomers of H₂O₆ display nearly the same enthalpy of formation, but only one of them has extremely long OO bonds. For H₂O₇, the most stable isomer also has two unusually long OO bonds. At the CCSD(T) level, and after extrapolation to the complete basis set limit, this isomer is predicted to be 5.37 kcal mol^–1 more stable than the one with short OO bonds, and the longest OO bond distance is expected to be close to 1.96 Å. Analysis of correlation energies indicated that the new isomers found for H₂O₆ and H₂O₇ are among the most strongly correlated molecules that can be formed with first-row atoms.

Keywords:

• polyoxides
• coupled cluster theory
• density functional theory
• thermochemistry
• infrared spectroscopy

Additional information

Funding

The authors acknowledge programa experimental para el desarrollo de las ciencias basicas (PEDECIBA), comision sectorial de investigacion cientifica (CSIC) and agencia nacional de investigacion e innovacion (ANII) (FSE6160) for financial support.