Since their first synthesis by Staudinger over a century ago, ketenimines, the nitrogen analogs of ketenes (C=C=NR), have transitioned from curiosities to key reagents in synthetic chemistry (Figure ). The intrinsic polarization of the C=C=N bond and the ability of ketenimines to participate in nucleophilic, electrophilic, and pericyclic reactions make them excellent reagents for synthesizing complex molecules, particularly through cycloadditions that yield diverse heterocyclic frameworks. The reactivity of ketenimines can be fine-tuned by modifying the substituents on the alkene or imine moiety, offering a high degree of synthetic flexibility. Ketenimines have been synthesized using a variety of different methods, with the Wittig reaction between phosphorus ylides and isocyanates, or between aza-Wittig reagents and ketenes being among the most commonly employed approaches. Further methods involve the coupling of stable singlet or Fischer carbenes with isonitriles, or the rearrangement of ynamines through a 1,3-shift of a leaving group from the nitrogen to the carbon atom. s-Block metal keteniminyl anions represent promising reagents to access ketenimines via simple nucleophilic substitution reactions. However, these anions have only poorly been described in present literature and no isolation has been attempted so far. For example, Masson reported the in-situ formation of the lithiated silylketenimine A through deprotonation of the corresponding ketenimine or elimination and subsequent deprotonation from an enaminate, but no spectroscopic data was provided. Keteniminyl complexes with other metals have been reported, but with limited applications in synthesis. Metal ynamides represent the metallo tautomers of metal keteniminyls, in which the metal is bound to the nitrogen instead of the carbon end. Similar to keteniminyl anions, they have been proposed as intermediates in several transformations, but only little been investigated as isolable reagents. The only example of an s-block metal ynamide, lithium complex B, was prepared by Lappert through an unusual coupling of two isocyanide molecules with a silyllithium reagent. Recently, we reported on a new synthetic pathway to ketenes from isolable ketenyl anions D synthesized through the mild exchange of the phosphine ligand in metalated ylides C by carbon monoxide (Figure ). Using this approach, we successfully isolated a series of phosphinoyl-, tosyl-and cyano-substituted ketenyl anions, which proved to be excellent precursors to ketenes and a large range of carbonyl-containing compounds. Shortly after, Liu and coworkers reported the formation of the stable (phosphino)ketenyl anion G via an N2/CO exchange in diazomethanides E (Figure ), a strategy previously used in-situ in ketene chemistry. Besides metalated ylides and diazomethanides also neutral diazoalkenes have been reported by Hansmann and coworkers to undergo an exchange of the N2 moiety when treated with carbon monoxide or 2,6-dimethylphenyl isocyanide. These exchange reactions are reminiscent of ligand exchange reactions known in transition metal chemistry for decades. While many low valent main group compounds like borylenes, aluminylenes, or phosphinidenes have also been reported to undergo similar ligand exchange reactions, this concept was rarely applied to carbon compounds. It is important to note that these reactions are conceptually distinct from typical nucleophilic substitution reactions. In this case, the strongly nucleophilic carbon attacks an ambiphilic reagent, where both its σ-donor and π-acceptor properties play a crucial role in enabling the reaction to proceed. These reactions align well with experimental and computational studies on the bonding in ylidic compounds, which led to a rethinking of carbon chemistry and the description of the phosphorus carbon bond as a dative interaction (C←:L) similar to the bonding interactions in transition metal phosphines complexes. This description of carbon compounds as coordination complexes was soon after applied to other carbon compounds with N-heterocyclic carbenes (NHC) or carbon monoxide as ligands. The N2/CO and PPh3/CO exchange reactions to ketenyl anions suggest that ligand exchange at carbon represents a broader strategy for generating metalated reagents. However, unlike CO, a straightforward PPh3/N2 exchange with dinitrogen was unsuccessful. This limiation could be overcome using nitrous oxide, which facilitated the reaction through phosphine oxide elimination. These findings prompted us to explore the scope of phosphine exchange in ylidic compounds with other neutral ligands. Herein, we present the mild PPh3/isocyanide and N2/isocyanide exchange as a novel approach to access isolable alkali metal keteniminyl anions.