Laser-ablated group 2 metal atoms have been reacted with O-2 in condensing N-2 to complement earlier Ar studies owing to different relaxation dynamics of N-2 and Ar with respect to excited metal atoms and ionic product molecules. In the case of Ca + O-2, the reaction in condensing Ar gives primarily the B-3(2) Open bent OCaO dioxide product, but the reaction in condensing N-2 favors the (1)A(1) cyclic CaO2 peroxide species. Three fundamentals are observed with O-18 and Ca-44 substitution for CaO2, and isotopic frequencies are in excellent agreement with the predictions of quantum chemical calculations. Although DFT/B3LYP frequencies are slightly higher than MP2 and CASSCF values, a similar pattern is calculated. Ionic molecules interact more strongly with a nitrogen matrix than with argon, and calculations of N(2)MO(x) and ArMO(x) molecules can be used to explain matrix shifts. Several N(2)MO(2) species are formed spontaneously from MO(2) molecules in solid nitrogen, and a match is found for observed matrix and DFT calculated isotopic frequencies. By comparison, the new molecule ArBeO2 is identified in earlier argon matrix experiments. The new metal disuperoxide molecules, O(2)MO(2), are also identified here. Calcium disuperoxide, O2CaO2, is characterized as a D-2d species with +1.12 charge on Ca and -0.28 on each O, in contrast to calcium peroxide, CaO2, a C-2v molecule with +1.05 charge on Ca and -0.525 on each oxygen atom.