COBALT, RHODIUM, AND IRIDIUM DIOXIDE MOLECULES AND WALSH-TYPE RULES

CoO2, RhO2, and IrO2, readily formed by the reaction of laser-vaporized metal atoms with oxygen, have been shown to be linear with 2-SIGMA ground states. This was established by electron-spin-resonance spectra of the molecules isolated in solid argon at approximately 2 K. Co-59(I = 7/2), Rh-103(I = 1/2), Ir-191, Ir-193(I = 3/2), and O-17(I = 5/2) hyperfine splittings have been obtained and indicate that the electron spin is predominantly on the metal atom and has approximately 50% s-sigma character. Attempts to observe the metal atom-O2 complexes were not successful. A Walsh-type rule applied to transition-metal dioxides is supported by the geometries found here.