The utilization of carbon monoxide as a C1 feedstock dates back to 1834 when Liebig demonstrated the reductive homologation of CO with molten potassium. Several industrial processes exploit the functionalization of CO on very large scales, such as the Fischer-Tropsch and Oxo process for the conversion of synthesis gas (syngas, a mixture of CO and H2) into hydrocarbons and aldehydes; and the Monsanto and Cativa processes that convert methanol into acetic acid with CO using rhodium and iridium catalysts, respectively. Although this field of chemistry was once dominated by transition metalcatalyzed reactions, there has been growing interest in the functionalization of CO using main-group compounds. In our own recent work, we have explored the activation of CO with alkali metal salts of reactive nucleophiles. Potassium di-tertbutylphosphide and benzyl potassium both react with CO to yield intermediates with carbene character. Lithium dicyclohexylamide enabled transition metalfree Fischer-Tropsch chemistry, and various alkali metal silylamides could readily convert CO into cyanide (CN -) and isocyanides (RNC). Most pertinently to the current work, we showed that a dilithiomethane derivative featuring two phosphine sulfide substituents could react with CO, and this intermediate was oxidized with N2O to afford an anionic ketenate (A, Scheme 1b). This ketenate could be heated to promote cyclo-trimerization and the formation of a hexa-functionalized benzene. The Gessner group subsequently developed an elegant synthesis of anionic ketenates by reacting CO with an alkali metal ylid derivative (B), and demonstrated that this ketenate moiety could be transferred to a range of electrophiles. This process was explored in more detail to enable selectivity control of the ketenate formation. The Liu group also developed a synthesis of a (phosphino)ketenate by reaction of the corresponding (phosphino)diazomethyl anion and CO (C). In the present study, we explore the functionalization of CO targeting the first large-scale synthesis of the fundamental [NCCCO] -anion as the [K(18-crown-6)] + salt (Scheme 1c). We probe its solidstate and electronic structure, explore its reactivity with respect to electrophiles, and synthesize the parent cyanoketene stabilized by a carbene. We note that shortly before our submission of this manuscript, a pre-print from the Gessner group appeared on ChemRxiv detailing the synthesis of the [NCCCO] - anion and reactivity towards E-H bonds (E = O, N, S), CO2 and a SO2 adduct.