A Biomimetic Nickel Complex with a Reduced CO₂ Ligand Generated by Formate Deprotonation and Its Behaviour towards CO₂

Abstract

Reduced CO species are key intermediates in a variety of natural and synthetic processes. In the majority of systems, however, they elude isolation or characterisation owing to high reactivity or limited accessibility (heterogeneous systems), and their formulations thus often remain uncertain or are based on calculations only. We herein report on a Ni-CO complex that is unique in many ways. While its structural and electronic features help understand the CO -bound state in Ni,Fe carbon monoxide dehydrogenases, its reactivity sheds light on how CO can be converted into CO/CO by nickel complexes. In addition, the complex was generated by a rare example of formate β-deprotonation, a mechanistic step relevant to the nickel-catalysed conversion of H CO at electrodes and formate oxidation in formate dehydrogenases.

Synthesis and reactivity of a nickel(ii) thioperoxide complex: demonstration of sulfide-mediated N2O reduction

“…While a monothiopercarbonate complex has not been previously reported, the reaction of metal peroxides (O 2 2– ) with CO 2 is known to yield peroxocarbonate ([OOCO 2 ] 2– ) complexes. 68 – 71 Similarly, metal disulfides (S 2 2– ) are known to react with CS 2 to form perthiocarbonates ([SSCS 2 ] 2– ). 72 , 73 Moreover, peroxocarbonates are known to be very effective O-atom donors.…”

Selective CO2 Splitting by Doubly Reduced Aryl Boranes to Give CO and [CO3]2−

“…[3] Theo ne-electron reduction of CO 2 occurs only at very cathodic potential values,m ainly because of the energy penalty associated with bending of the linear molecule upon electron uptake to furnish the [CO 2 ]C À radical. [7][8][9][10] Since the advent of frustrated Lewis pair (FLP) chemistry, increasing efforts have been devoted to the replacement of transition-metal catalysts by appropriate combinations of main-group Lewis acids and bases.I nt he context of CO 2 activation, ap lethora of capture products such as R 3 P-C(O)-O-BR' 3 are nowadays known. [1a] Some transition-metal com-pounds can act as nucleophiles toward CO 2 molecules and thereby transfer two electrons simultaneously onto the substrate,w hich is afterwards stabilized through p backbonding (see below).…”

“…CO reduction under mild conditions,a lbeit not always in ac atalytic fashion. [7][8][9][10] Since the advent of frustrated Lewis pair (FLP) chemistry, increasing efforts have been devoted to the replacement of transition-metal catalysts by appropriate combinations of main-group Lewis acids and bases.I nt he context of CO 2 activation, ap lethora of capture products such as R 3 P-C(O)-O-BR' 3 are nowadays known. Follow-up reactions with various reducing agents have been studied and the palette of obtainable compounds encompasses CO,H C(O)OH, H 3 COH, and CH 4 .…”

Selective CO2 Splitting by Doubly Reduced Aryl Boranes to Give CO and [CO3]2−

“…Some transition‐metal compounds can act as nucleophiles toward CO 2 molecules and thereby transfer two electrons simultaneously onto the substrate, which is afterwards stabilized through π backbonding (see below). Indeed, several metal complexes exist that are capable of achieving the CO 2 → CO reduction under mild conditions, albeit not always in a catalytic fashion …”