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Laser-ablated Co atoms react with O2 to give the linear dioxide, the monoxide, and the rhombic (CoO)2 dimer molecules. The linear OCoO molecule is characterized by oxygen-18 substitution in strong ν3 (945.4 cm-1) fundamental and weak ν1+ν3 (1717.6 cm-1) combination bands. Annealing to 20−30 K to allow diffusion and reaction of cold cobalt atoms and dioxygen markedly increases weak bands due to the Co(O2) and CoOO complexes and higher species including OOCoO, OOCoO2, (O2)CoO2, and the dimer (CoO2)2. DFT and CASSCF calculations performed on the three CoO2 isomers and rhombic (CoO)2 support these assignments; DFT calculations are also presented for the rhombic (FeO)2 molecule.

Platinum and palladium atoms produced by laser ablation were reacted with dioxygen diluted in argon during condensation at 10 K. Reaction products, including the M(O2) and (O2)M(O2) complexes prepared with thermal metal atoms, and the platinum oxides PtO, OPtO, PtO3, OOPtO, and (O2)PtO, were analyzed by matrix infrared spectroscopy. Absorptions due to PdO and OPdO were not identified. Density functional theory (B3LYP) calculations were performed on product molecules, which were identified on the basis of isotopic frequency shifts and correlation with density functional calculations. The most interesting new molecule produced here, linear OPtO, can also be produced by photolysis of the cyclic Pt(O2) complex.

Laser-ablated Co and Ni atoms, co-deposited with pure nitrogen at 10 K, gave a strong new 795.3 cm -1 band with cobalt and a 838.8, 836.1 cm -1 isotopic doublet (2.5/1.0) with nickel, which exhibited 14/15 isotopic ratios appropriate for the diatomic CoN and NiN molecules. In solid argon, CoN absorbs at 826.5 cm -1 and gives way on annealing to bands at 795.8 and 792.0 cm -1 , which are due to (NN) x CoN complexes. Density functional theory (DFT) calculations predict quintet and quartet ground states for CoN and NiN, respectively, and frequencies in reasonable agreement with the observed values. Evidence is also presented for the dimetal dinitrides, (CoN) 2 and (NiN) 2 , with rhombus structures and metal-metal bonding across the ring. DFTbased calculations and revised assignments are presented for Ni-NN stretching modes in the dinitrogen complexes.