Infrared Spectra and Density Functional Calculations of MO₂, MO₃, (O₂)MO₂, MO₄, MO₂⁻ (M = Re, Ru, Os) and ReO₃⁻, ReO₄⁻ in Solid Neon and Argon

Laser-ablated rhenium, ruthenium, and osmium atoms react with O 2 in excess neon and argon during condensation to form the MO 2 dioxide molecules as major products. The MO 3 trioxides with D 3 h symmetry, the (O 2 )MO 2 dioxide complexes with C 2 v symmetry, and the tetrahedral MO 4 (M = Ru, Os) molecules are formed on sample annealing. Photolysis converts the (O 2 )MO 2 complexes to the more stable MO 4 isomers. In addition, the MO 2 - dioxide anions and ReO 3 - and ReO 4 - anions are also formed via electron capture by the neutral molecules. The metal oxide neutrals and anions were identified from oxygen-18 substitution and natural metal isotopic splittings, and from DFT calculations of isotopic frequencies. Doping with CCl 4 to serve as an electron trap gave the same neutral molecule bands and virtually eliminated the anion absorptions, which further supports the anion identifications.