Reactions of laser-ablated iron and manganese oxides with dinitrogen in excess argon have been investigated by matrix-isolation infrared spectroscopy. The NNMO (M = Fe, Mn), (NN)(2)FeO, and NNFeO2 complexes are formed as reaction products during sample deposition and/or further annealing. These complexes are characterized on the basis of the results of the isotopic substitution and comparison with theoretical calculations. The agreement between the experimental and calculated vibrational frequencies and isotopic shifts supports the identification of these complexes from the matrix infrared spectra. Reaction mechanisms have been proposed for the formation of these products. (C) 2011 Elsevier B. V. All rights reserved.