Tri-organyl and tricoordinate N-heterocyclic carbene (NHC) Zn-NHC alkyl cations [(nNHC) Zn-Me] (nNHC=C2-bonded-IMes/-IDipp; 3 and 4 ; IMes=1,3-bis(2,4,6-trimethylphenyl)imidazolin-2-ylidene, IDipp=1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene) were first synthesized and structurally characterized by ionization of the corresponding neutral precursors [(nNHC)ZnMe ] with [Ph C][B(C F ) ] in the presence of one equivalent of free NHC. Whereas cation [(nIMes) Zn-Me] (3 ) is stable, its sterically congested analogue [(nIDipp) Zn-Me] (4 ) readily undergoes an nNHC-to-aNHC isomerization in the presence of THF or IDipp to afford the more thermodynamically stable [(aIDipp)(nIDipp)Zn-Me] (aIDipp=C4-bonded IDipp, 5 ), reflecting the adaptable-to-sterics coordination chemistry of these cations for improved stability. Cations 3 -5 are the first Zn cations of the type Zn(C)(C')(C'') (C, C', C''=σ-donor carbyl ligand). Kinetic studies combined with DFT calculations agree with an nNHC-to-aNHC process proceeding through the initial deprotonation of 4 (at a Zn-bonded C4-IDipp moiety) by IDipp. Unlike 3 and 4 , the rearranged cation 5 reacts with CO through insertion into the Zn-Me bond yielding the corresponding Zn(κ -OAc) cation 6 . Both cations 5 and 6 were successfully used in CO hydrosilylation catalysis for silylformate formation.

The reactivity of ZnII dialkyl species ZnMe2 with a cyclic(alkyl)(amino)carbene, 1‐[2,6‐bis(1‐methylethyl)phenyl]‐3,3,5,5‐tetramethyl‐2‐pyrrolidinylidene (CAAC, 1), was studied and extended to the preparation of robust CAAC‐supported ZnII Lewis acidic organocations. CAAC adduct of ZnMe2 (2), formed from a 1:1 mixture of 1 and ZnMe2, is unstable at room temperature and readily undergoes a CAAC carbene insertion into the Zn−Me bond to produce the ZnX2‐type species (CAAC‐Me)ZnMe (3), a reactivity further supported by DFT calculations. Despite its limited stability, adduct 2 was cleanly ionized to robust two‐coordinate (CAAC)ZnMe+ cation (5+) and derived into (CAAC)ZnC6F5+ (7+), both isolated as B(C6F5)4− salts, showing the ability of CAAC for the stabilization of reactive [ZnMe]+ and [ZnC6F5]+ moieties. Due to the lability of the CAAC−ZnMe2 bond, the formation of bis(CAAC) adduct (CAAC)2ZnMe+ cation (6+) was also observed and the corresponding salt [6][B(C6F5)4] was structurally characterized. As estimated from experimental and calculations data, cations 5+ and 7+ are highly Lewis acidic species and the stronger Lewis acid 7+ effectively mediates alkene, alkyne and CO2 hydrosilylation catalysis. All supporting data hints at Lewis acid type activation–functionalization processes. Despite a lower energy LUMO in 5+ and 7+, their observed reactivity is comparable to those of N‐heterocyclic carbene (NHC) analogues, in line with charge‐controlled reactions for carbene‐stabilized ZnII organocations.