Carbon Dioxide Activation at Metal Centers: Evolution of Charge Transfer from Mg?.+ to CO2 in [MgCO2 (H2 O)n ].+ , n=0-8.

ABSTRACT: We investigate activation of carbon dioxide by singly charged hydrated magnesium cations Mg?.+ (H2 O)n , through infrared multiple photon dissociation (IRMPD) spectroscopy combined with quantum chemical calculations. The spectra of [MgCO2 (H2 O)n ].+ in the 1250-4000?cm-1 region show a sharp transition from n=2 to n=3 for the position of the CO2 antisymmetric stretching mode. This is evidence for the activation of CO2 via charge transfer from Mg?.+ to CO2 for n?3, while smaller clusters feature linear CO2 coordinated end-on to the metal center. Starting with n=5, we see a further conformational change, with CO2 .- coordination to Mg2+ gradually shifting from bidentate to monodentate, consistent with preferential hexa-coordination of Mg2+ . Our results reveal in detail how hydration promotes CO2 activation by charge transfer at metal centers.

SUBMITTER: Barwa E 

PROVIDER: S-EPMC7217156 | biostudies-literature | 2020 May

REPOSITORIES: biostudies-literature