The observed dimerization of the parent cyanoketene suggests that this species is amphoteric. Noting that strong donors such as N-heterocyclic carbenes (NHC) have been exploited to stabilize and isolate a wide range of highly reactive main-group compounds, we probed the corresponding reactivity of 1. To this end, 1 was treated with 1,3bis (2,4,6-trimethylphenyl) imidazolium chloride (IMes•HCl), which acted as a proton source and also generated the free NHC 1,3-bis-(2,4,6trimethylphenyl) imidazol-2-ylidene (IMes) that could trap the cyanoketene in situ and generate the carbene-stabilized cyanoketene (5) in a 46% yield. The yield could be improved by employing KHMDS as a base and proton-shuttle. In this case, the reaction is thought to proceed via initial deprotonation of IMes•HCl to afford IMes and HN(SiMe3)2. NHC attack of the electrophilic carbonyl position of 1 increases the basicity of C2 of the ketenate, enabling deprotonation of HN(SiMe3)2. The enhancement of the Bronsted basicity of the anion by the NHC is clear as 1 is formed in the presence of HN(SiMe3)2 and does not effect deprotonation on its own. Thermal ellipsoids at 50%, most hydrogen atoms are omitted for clarity. Atom colours: C (grey), O (red), N (blue), K (cyan), Si (orange), H (white). Selected bond metrics can be found in the SI. The formulation of 5 as an IMes carbene adduct with cyanoketene was confirmed through an X-ray diffraction experiment. Orange crystals suitable for X-ray diffraction were grown by slow diffusion of Et2O into an acetonitrile solution of 5 (Figure ). In the imidazolium-2-enolate, the C4-C3 bond distance was determined to be 1.512(2) Å, while the C3-O1, C3-C2, and C2-C1 distances were found to be 1.2552 (19), 1.381(2), and 1.410(2) Å, respectively. Notably, C2 and C3 were observed to be planar, with the sums of surrounding bond angles totaling 360°. These observations are indicative of charge delocalization from IMes to the cyanoketene C(O)-C-C fragment. In this arrangement, the oxygen atom and nitrile group are positioned in a cis-orientation on the C=C double bond. These structural parameters closely resemble those observed in the SIMes adduct with diphenyl ketene, as reported by Delaude in their mechanistic study of the NHC-catalyzed Staudinger reaction involving diphenyl ketene and imines. This work shows that the σ-donating NHC enables the interception of the parent cyanoketene and precludes dimerization.