Laser-ablated Mn atoms react with O-2 to give MnO, OMnO, (MnO)(2), and MnO2- 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)MnO2 oxide complexes, and higher oxides. The OMnO molecule is bent based on the observation of both vs and vl and on DFT calculations; the oxygen-18 shift for v(3) provides a valence angle determination of 135 +/- 5 degrees. The cyclic Mn(O-2) molecule involves a weaker bonding interaction than the cyclic Fe(O-2) molecule. The short 2.6 Angstrom estimated Mn-Mn distance across the rhombic (MnO)(2) ring is compatible with substantial metal-metal bonding.