Linear End‐On Coordination Modes of CO₂

Abstract

The second case of linear end-on and evidence for an unprecedented bridging end-on coordination mode of CO 2 have been discovered for vanadium aryloxide complexes of the tetradentate ligand system (ONNO) 2À (ONNO = 2,4-Me 2-2-(OH) C 6 H 2 CH 2 ] 2 N(CH 2) 2 NMe 2). The reaction of divalent (ONNO)V II (TMEDA) with CO 2 and under the appropriate reaction conditions affords the trivalent (ONNO)V III (OH)(h 1-CO 2)r esulting from an intermediate CO 2 deoxygenation pathway followed by H-atom abstraction from the aromatic solvent, and CO 2 fixation. In contrast, the reduction of trivalent (ONNO)V III Cl(THF) with K, followed by exposure to CO 2 in ethereal solvent, afforded the dinuclear [(ONNO)V II ] 2 (m , h 1-CO 2).

Recent Advances in the Chemistry of Metal Carbamates

“…The former goal is challenging for a variety of reactions, and a wide number of metal catalysts have been proposed to access valuable organic compounds and materials via CO 2 fixation strategies, which, however, require harsh conditions (high temperature and CO 2 pressure) in several cases [14,15]. 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].…”

Non-redox reactivity of V(ii) and Fe(ii) formamidinates towards CO2 resulting in the formation of novel M(ii) carbamates

“…The observed CO 2 insertion into the V-N bonds of 2, which resulted in the formation of divanadium tetra(carbamate) compound 4, contrasts with documented by Gambarotta multielectron reductions of CO 2 by V(II) and V(III) systems. [27][28][29] The lack of oxidation of the low-valent V(II) centre and the following C-O bond cleavage could seem surprising. This phenomenon was probably caused by the strong nucleophilicity of the N-donor amidinate ligand.…”

“…10 For example, it was only in 2017 that Gambarotta et al reported the first well-documented processes of CO 2 reduction by V(II) and V(III) systems. [27][28][29] As part of our continuous effort in designing various new reaction systems for small molecules activation 30,31 and using of CO 2 as a substrate in the preparation of functional materials, 32,33 herein we examine the reactivity of model mononuclear amidinate complexes of V(II) and Fe(II) towards CO 2 and present their ability to capture multiple equivalents of CO 2 .…”

Carbon photochemistry: towards a solar reverse boudouard refinery

“…1e). 25,26 The carbon black C n B used in this study has a high surface area (216 m 2 g À1 ) and strongly adsorbs CO 2 through hydrogenbonding interactions with surface hydroxyl, carboxyl, and aromatic functionalities. The bound CO 2 is denoted by C n BÁ Á ÁCO 2 (Fig.…”