Carbon-carbon bonds with CO2: Insights from computational studies

Abstract

a b s t r a c tIn this mini-review, we provide an overview of recent computational studies on homogeneous transition metal-catalyzed carbon-carbon bond formation with CO 2 . We cover substitution and addition reactions involving different metals (mainly Ni, Rh, Cu) and substrates (alkanes, alkenes, alkynes, arenes) with focus on the mechanistic details. The CO 2 insertion step is generally found to be rate-limiting. The reported transition state geometries for C-C bond formation mostly display three-membered cyclic arrangements involving the metal and the two reacting carbon atoms, except for reaction with C sp atoms, where acyclic conformations are observed. Other reported exceptions point to that an interaction of CO 2 with the metal catalyst may not be essential. Several studies suggest that Lewis acid additives could help activating CO 2 during C-C bond formation.

Rhodium-Catalyzed Hydrocarboxylation: Mechanistic Analysis Reveals Unusual Transition State for Carbon–Carbon Bond Formation

“…This is in contrast to predictions on related reactions, which propose a CO2-metal interaction. 8,9,10,11,12,13,14,20,21,22,23,24 In addition, we find that for the five studied substrates, the energetically lowest-lying TS geometries all show an unusual coordination mode of the substrate through the phenyl ring instead of through the nucleophilic carbon. Our calculations indicate that the rate-limiting CO2 insertion barrier could provide an explanation to why esters are reactive and amides are unreactive.…”

Insertion of CO2 Mediated by a (Xantphos)NiI–Alkyl Species

“…In contrast, sp and sp 2 nucleophiles cannot access such a pathway, but can only undergo migratory insertion (Scheme B). The approach of CO 2 to these ( t Bu‐Xantphos)Ni I complexes is inhibited by the bulky substituents on the ligand . The lack of reactivity of 8 with CO 2 can be attributed to the lower nucleophilicity of phenoxides compared with carbanions.…”

Machine learning dihydrogen activation in the chemical space surrounding Vaska's complex

“…Computational chemistry has become a powerful tool in homogeneous catalysis, and combined with experiments, delivers molecular models enabling the rational design of catalytic systems. [13][14][15][16][17][18][19][20][21][22] However, the key ligands and substituents of these models are classied with generic labels (e.g., 'strong p-acceptor', 'bulky' or 'proton-acceptor') that can be assigned to tens or hundreds of known compounds. The combination of all these possibilities yields a region of the chemical space 23 containing thousands of catalyst candidates.…”