Synergetic electron donation and back-donation interactions in (Au − CO2)− complex: A joint anionic photoelectron velocity-map imaging spectroscopy and theoretical investigation

Abstract

The reaction of Au− with CO2 has been investigated by photoelectron velocity-map imaging. The chemisorbed (Au − CO2)− complex is predominant in the experiment. The further reduction of CO2 into CO is theoretically proved to be thermodynamically endothermic and kinetically infeasible. Nevertheless, the bent CO2 moiety and elongated C − O bonds provide the clearest sign for anionic activation of CO2. Chemical bonding analyses indicate that there are electron back-donations from the 5d/6s atomic orbitals of Au− to the anti-bonding π orbitals of CO2, in synergy with unprecedented donation from the delocalized bonding orbitals of CO2 to the metal 6p atomic orbital.