Photoelectron spectroscopic and computational study of (M–CO2)− anions, M = Cu, Ag, Au

Abstract

In a combined photoelectron spectroscopic and computational study of (M-CO2)(-), M = Au, Ag, Cu, anionic complexes, we show that (Au-CO2)(-) forms both the chemisorbed and physisorbed isomers, AuCO2(-) and Au(-)(CO2), respectively; that (Ag-CO2)(-) forms only the physisorbed isomer, Ag(-)(CO2); and that (Cu-CO2)(-) forms only the chemisorbed isomer, CuCO2(-). The two chemisorbed complexes, AuCO2(-) and CuCO2(-), are covalently bound, formate-like anions, in which their CO2 moieties are significantly reduced. These two species are examples of electron-induced CO2 activation. The two physisorbed complexes, Au(-)(CO2) and Ag(-)(CO2), are electrostatically and thus weakly bound.

A photoelectron spectroscopic and computational study of the o-dicarbadodecaborane parent anion

“…The NPA method has been found to be satisfactory in calculating the charge distribution within a cluster. [27][28][29][30][31][32][33]…”

Can a Single Valence Electron Alter the Electrocatalytic Activity and Selectivity for CO2 Reduction on the Subnanometer Scale?

“…The fact that CO 2 is only physisorbed on Cu 6 perhaps illustrates the fact that this cluster, which has six Cu 3s electrons, has a particularly stable “magic number” electron count (6e) corresponding to a closed shell for the solution of the Schrödinger equation for an electron constrained to a circular disk. In water, chemisorption (on Cu 3 , Cu 4 , and Cu 5 ) involves CO 2 bending and cluster-to-CO 2 charge transfer, which is considerably higher in magnitude (− q CO 2 > 0.8) than in the gas phase, closer to the formatelike structure observed on Cu – in the gas phase . As in the gas phase, the linear physisorbed CO 2 molecule on Cu 6 has a small positive charge ( q CO 2 = +0.01).…”

“…It should be noted that, in a combined photoelectron spectroscopy and computational study, Bowen et al have reported the formation of a gas-phase complex between CO 2 and a single Cu − anion, which results in electron transfer and the formation of Cu(CO 2 − ), where the CO 2 − moiety is bent and bonded to Cu via the carbon atom, with the negative charge delocalized over the π* framework of the coordinated CO 2 , corresponding to a formate-like complex. 94 Interestingly, Cu − only forms the chemisorbed complex with CO 2 , whereas Ag − forms only a C-bound physisorbed complex (with quasi-Table 1. Adsorption Free Energies (ΔG ads /eV) and Geometries of the CO 2 * (CO 2 -Adsorbed Complexes) for Different Cu n (n = 3−6) Clusters in the Gas Phase and Water a a The net NBO charges on the adsorbed CO 2 molecule (q CO 2 ) are also listed.…”

“…In water, chemisorption (on Cu 3 , Cu 4 , and Cu 5 ) involves CO 2 bending and cluster-to-CO 2 charge transfer, which is considerably higher in magnitude (−q CO 2 > 0.8) than in the gas phase, closer to the formatelike structure observed on Cu − in the gas phase. 94 As in the gas phase, the linear physisorbed CO 2 molecule on Cu 6 has a small positive charge (q CO 2 = +0.01).…”

Computational Exploration of the Direct Reduction of CO2 to CO Mediated by Alkali Metal and Alkaline Earth Metal Chloride Anions

“…It is well established that metal atoms and anions may add CO 2 to form complexes in gas phase reactions, formally metal carbonites (MCO 2 ). Their preferred structures are shown in Scheme , which in the case of alkali and alkaline earth metals is the bidentate coordination of the metal to both oxygen atoms (κ 2 -O 2 C), − while for transition metals, the metal typically binds to the carbon atom (η 1 -CO 2 ) or in a side-on fashion (η 2 -CO 2 ). − Early transition metals, M = Sc, Ti, V, and Cr, ,,− even insert into one of the C–O bonds with subsequent CO elimination: …”