Chemical reduction of CO₂facilitated by C-nucleophiles

Abstract

The abundance of atmospheric CO presents both an opportunity and a challenge for synthetic chemists to transform CO into value-added products. A promising strategy involves CO reduction driven by the energy stored in chemical bonds and promoted by molecules containing nucleophilic carbon sites. This approach allows the synthesis of new C-C or C-H bonds from CO-derived carbon. The first part of this Feature article deals with uncatalyzed reductions of CO such as insertion into metal-carbon bonds and reactivity towards multidentate actor ligands and metal-free compounds. The second part covers catalytic reduction of CO in which a nucleophilic C-site is involved. This review brings together two general approaches in the chemical CO reduction field, showing how the discovery of fundamental reactivity of CO leads to synthetic applications, and proposes directions for further development.

Recent Advances in the Chemistry of Metal Carbamates

“…57 [b] 4.37 1.9 × 10 5 1.3 × 10 −2 [56] Taurine [b], [c] 5.19 7.1 × 10 3 5.1 × 10 −2 [57] Amino acids Glycine [d] 4.49 4.4 × 10 4 4.2 × 10 −2 [59] Sarcosine [b], [d] 4. 22 3.3 × 10 4 1.0 × 10 −1 [60] α-Alanine [d] 4.40 1.8 × 10 4 1.1 × 10 −1 [61] Table 1. Cont.…”

“…It is worthy to note that, differently to other small molecules such as its relative carbon monoxide, carbon dioxide is a “bad” ligand for transition metals; therefore, examples of simple coordination compounds are relatively rare [ 16 , 17 , 18 , 19 , 20 , 21 ] and, accordingly, metal catalysts working in CO 2 activation routes usually exert their action without the intermediacy of metal-CO 2 adducts. The “weak point” in the apparently unscratchable robustness of carbon dioxide is the susceptibility to nucleophilic attacks at the carbon atom [ 22 , 23 , 24 ]. Thus, a range of nucleophilic reagents, including neutral N -heterocyclic carbenes [ 25 , 26 ], are known to react with CO 2 even under mild conditions, and some chemistry at transition metal centers is provided by the possibility of CO 2 insertion into the bond between a metal atom and a suitable anionic ligand, e.g., alkyl, allyl, alkoxide and hydride [ 27 , 28 , 29 , 30 , 31 , 32 ].…”

Direct Photochemical C–H Carboxylation of Aromatic Diamines with CO2 under Electron-Donor- and Base-free Conditions

“…In the former case, several thermal hydrogenation 8 , 9 , electro- 17 – 19 , and photo-catalytic systems 17 , 18 , 20 , 21 that produce reduced C 1 chemicals, e.g., CH 3 OH 22 – 24 , CO 25 – 30 , HCO 2 H 31 – 33 , and HCO 2 − 34 – 36 have been investigated. In the latter case, carboxylic acids are formed, which represent a central motif in a variety of synthetically important chemicals 37 – 50 .…”

Unexpected Macrocyclic Multinuclear Zinc and Nickel Complexes that Function as Multitasking Catalysts for CO2 Fixations

“…[12] TheZ n 1 -Zn 3 ions were arranged to form an early isosceles triangle,a nd the dihedral angles of the naphthalene rings of each binaphthyl differed:688 8,728 8,and 888 8,because the inner part was horizontally long. On the other hand, the Ni II complexes exhibited polymorphism (Scheme 1; Supporting Information, Scheme S2), and two types of single crystals of macrocyclic complexes were obtained ( (5). Complex 3 consisted of am acrocyclic part (Ni 3 L 3 )a nd an inner part (Ni(OH) 2 (H 2 O) 2 ).…”