Spectroscopic identification of a bidentate binding motif in the anionic magnesium-CO2 complex ([ClMgCO2 ](-))
Glenn B S Miller1, Tim K Esser, Harald Knorke
1Massespektrometrilaboratoriet and Senter for teoretisk og beregningsbasert kjemi (CTCC), Kjemisk institutt, Universitetet i Oslo, Postboks 1033 Blindern, 0315 Oslo (Norway).
Abstract:
A magnesium complex incorporating a novel metal-CO2 binding motif is spectroscopically identified. Here we show with the help of infrared photodissociation spectroscopy that the complex exists solely in the [ClMg(η(2) -O2 C)](-) form. This bidentate double oxygen metal-CO2 coordination has previously not been observed in neutral nor in charged unimetallic complexes. The antisymmetric CO2 stretching mode in [ClMg(η(2) -O2 C)](-) is found at 1128 cm(-1) , which is considerably redshifted from the corresponding mode in bare CO2 at 2349 cm(-1) , suggesting that the CO2 moiety has a considerable negative charge (∼1.8 e(-) ). We also employed electronic structure calculations and kinetic analysis to support the interpretation of the experimental results.
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