Reactions of Laser-Ablated Manganese Atoms with Dioxygen. Infrared Spectra of MnO, OMnO, Mn(O2), (MnO)2, and Higher Oxide Complexes in Solid Argon

Laser-ablated Mn atoms react with O 2 to give MnO, OMnO, (MnO) 2, and MnO 2 - as major products, which are identified from oxygen isotopic substitution on their matrix infrared spectra. Annealing allows further association to form the cyclic Mn(O 2 ) complex, (O 2 )MnO and (O 2 )MnO 2 oxide complexes, and higher oxides. The OMnO molecule is bent based on the observation of both ν 3 and ν 1 and on DFT calculations; the oxygen-18 shift for ν 3 provides a valence angle determination of 135 ± 5°. The cyclic Mn(O 2 ) molecule involves a weaker bonding interaction than the cyclic Fe(O 2 ) molecule. The short 2.6 Å estimated Mn−Mn distance across the rhombic (MnO) 2 ring is compatible with substantial metal−metal bonding.