Although neutral and ionic O-4(0/-/+) Species have been observed experimentally and considered for energetic materials, O-4(2-) and O-5(2-) dianions have not yet been explored. O-4(2-) is valent isoelectronic to the well-known C\O-3(-) and SO32-anions, and O-5(2-) is valent isoelectronic to C\O-4(-) and SO42-. All are stable, common anions in solutions and inorganic salts. In this article, we explore the possibility of making covalenty bound O-4(2-) and O-5(2-) species stabilized in the forms Of M+O42- and M+O52- (M = Li, Na, K, Cs) in the gas phase. Laser vaporization experiments using M-containing targets and an O-2-seeded carrier gas yielded very intense mass peaks corresponding to MO4- and MO5-. To elucidate the structure and bonding of the newly observed MO4- and MO5-species, we measured their photoelectron spectra and then compared them with ab initio calculations and the spectra of C\O-3(-), Na+SO32-, C\O-4(-), and Na+SO42-. Careful analyses of the experimental and ab initio results showed, however, that the observed species are of the forms, O-2-M-O-2(-) and O-2-M+O3-. The more interesting M+O-4(2-) and M+O52- species were found to be higher-energy isomers, but they are true minima on the potential energy surfaces, which suggests that it might be possible to synthesize bulk materials containing covalently bound tetra- and pentatomic oxygen building blocks.