The reaction chemistry of the side-on bound (N-2)(2)(-), (N-2)(3)(-), and (NO)(2-) complexes of the [(R2N)(2)Y](+) cation (R = SiMe3), namely, [(R2N)(2)(THF)Y](2)(mu-eta(2):eta(2)-mu(2)), 1, [(R2N)(2)(THF)-Y](2)(mu-eta(2):eta(2)-N-2)K, 2, and [(R2N)(2)(THF)Y](2)(mu-eta(2):eta(2)-NO), 3, with oxidizing agents has been explored to search for other (E-2)(n-), (E = N, O), species that can be stabilized by this cation. This has led to the first examples for the [(R2N)(2)Y](+) cation of two fundamental classes of [(monoanion)(2)Ln](+) rare earth systems (Ln = Sc, Y, lanthanides), namely, oxide complexes and the tetraphenylborate salt. In addition, an unusually high yield reaction with dioxygen was found to give a peroxide complex that completes the (N-2)(2-), (NO)(2-), (O-2)(2-) series with 1 and 3. Specifically, the (mu-O)(2-) oxide-bridged bimetallic complex, [(R2N)(2)(THF)Y}(2)(mu-O), 4, is obtained as a byproduct from reactions of either the (N-2)(2-) complex, 1, or the (N-2)(3-) complex, 2, with NO, while the oxide formed from 2 with N2O is a polymeric species incorporating potassium, ([(R2N)(2)Y](2)(mu-O)(2)K-2(mu-C7H8)}, 5. Reaction of 1 with 1 atm of 02 generates the (O-2)(2-) bridging side-on peroxide [(R2N)(2)(THF)Y](2)(mu-eta(2):eta O-2-(2)), 6. The O-O bond in 6 is cleaved by KC8 to provide an alternative synthetic route to 5. Attempts to oxidize the (NO)2- complex, 3, with AgBPh4 led to the isolation of the tetraphenylborate complex, [(R2N)(2)Y(THF)(3)][BPh4], 7, that was also synthesized from 1 and AgBPh4. Oxidation of the (N-2)(2-) complex, 1, with the radical trap (2,2,6,6-tetramethylpiperidin-1-yl)oxyl, TEMPO, generates the (TEMPO)(-) anion complex, (R2N)(2)(THF)Y(eta(2)-ONC5H6Me4), 8.