Laser-ablated rhenium, ruthenium, and osmium atoms react with O-2 in excess neon and argon during condensation to form the MO2 dioxide molecules as major products. The MO3 trioxides with D-3h symmetry, the (O-2)MO2 dioxide complexes with C-2v symmetry, and the tetrahedral MO4 (M = Ru, Os) molecules are formed on sample annealing. Photolysis converts the (O-2)MO2 complexes to the more stable MO4 isomers. In addition, the MO2-dioxide anions and ReO3- and ReO4- 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 CCl4 to serve as an electron trap gave the same neutral molecule bands and virtually eliminated the union absorptions, which further supports the anion identifications.