In this computational study, we address materials composed formally of K and CO, and focus especially on K3C6O6, a material we predict to feature oxocarbon radical anions, extreme metallicity and the potential for rare π-band superconductivity. Our study is in part motivated by the possibility of producing metallic organic salts, i.e., compounds where ionic and covalent bonding situations are mixed in a metallic solid-state structure. Such compounds can exhibit a range of properties needed in, for example, spintronics, superconductors, optoelectronic devices, and electrochemical sensors. CO is a common ligand useful for probing electronic structure in part due to its ability to engage in π-backdonation. However, CO can also react with itself. The thermodynamic ground state of CO in the condensed phase is experimentally uncertain. Predictions (at T→0K) indicate that the ground state is not molecular, but akin to a lactone-like polymer. A variety of CO-based polymeric structures, both metallic and narrow band gap semiconductors, have been observed at elevated pressures. The reactivity of CO is increased by reduction, which allows it to undergo homologation reactions, forming oxocarbon anions. Such processes constitute potent C-C coupling routes and synthesis of oxycarbon-based materials have been pursued for over a century. The first attempts were probably made by Berzelius, Wohler, and Kindt 15 in 1823, who reacted potassium hydroxide with carbon to form dipotassium croconate (K2C5O5). Around the same time, Liebig circulating CO through molten potassium and made what was much later identified as a mixture of potassium ethynediolate and potassium benzenehexolate. Since then, a variety of s-, p-, d-and fblock elements have been used to reduce CO, yielding different oxocarbon compounds (see e.g., ref 9 and references therein). Some oxocarbon compounds are stabilized by extensive π-conjugation, and anions tend to adopt cyclic structures with all carbon atoms bonded to a carbonyl or an enolic oxygen atom. Interest in such materials have various motivations: Materials such as oxocarbon squarate, Li2C4O4, are promising anode materials. Others, such as M2C6O6 (M=Li, Na and K), are ultrahigh capacitors and cathode materials. Pb3C6O6 is a potential photovoltaic material, while M(C6O6) (M=Fe, Co, Mn), 26 Mn5(C6O6)2, and Cu3(C6O6)2 are examples of narrow-band-gap metal organic frameworks. Some oxocarbon anions facilitate the production of hydrocarbons though Fischer-Tropsch-type processes. Several studies have focused on the properties of these molecular anions, including, for example, how the aromaticity (or anti-aromaticity) of anions may vary with charge. In contrast, relatively little attention have been paid to the bonding situation in the solid state, where ionic, covalent and van der Waals interactions can combine to create unique extended chemical structures (see e.g., ). In what follows, we outline predictions of the solid-state phase diagram of Kn(CO)m at ambient conditions of pressure. We then focus on explaining the unusual P6/mmm ground state of K3C6O6, which we predict to be both highly ionic, metallic, and superconducting. Finally, we propose K3C6O6 as a design template for a family of conductors and superconductors, and we outline rationales for engineering their electronic structure.