We have described the PPh3/isocyanide and N2/isocyanide exchange in a metalated ylide and diazomethanide as pathways to isolable keteniminyl anions. The potassium complexes could be isolated in good to excellent yields and spectroscopically as well as crystallographically been characterized. All anions feature a bent geometry, with the bending angle decreasing, with increasing donor ability of the nitrogen substituent. The structural features of the anions can be described by an intermediate bonding situation between that of a ketenimine and ynamine. While donating groups at nitrogen favor the keteniminyl structure, accepting substituents shift the bonding situation towards an ynamide structure. Computational studies explain this trend through the π-accepting properties of the isocyanide ligands in line with the Dewar-Chatt-Duncanson concept commonly applied in transition metal chemistry. The keteniminyl anions proved to be versatile reagents for forming highly functionalized heterocycles by reaction with unsaturated compounds. [2+2], [2+3] and [2+4] cycloadditions allow access to a range of scaffolds, including novel heterocycle. These reactions underscore the potential of ligand exchange processes in generating functional building blocks for synthesis, offering opportunities for future expansion to other ylide precursors, isocyanides, and unsaturated carbon compounds.