title: Spectroscopic identification of a bidentate binding motif in the anionic magnesium-CO2 complex ([ClMgCO2 ](-)).
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.
authors.affiliation: Massespektrometrilaboratoriet and Senter for teoretisk og beregningsbasert kjemi (CTCC), Kjemisk institutt, Universitetet i Oslo, Postboks 1033 Blindern, 0315 Oslo (Norway).
authors.forename: Glenn B S
authors.initials: GB
authors.lastname: Miller
authors.forename: Tim K
authors.initials: TK
authors.lastname: Esser
authors.forename: Harald
authors.initials: H
authors.lastname: Knorke
authors.forename: Sandy
authors.initials: S
authors.lastname: Gewinner
authors.forename: Wieland
authors.initials: W
authors.lastname: Schöllkopf
authors.forename: Nadja
authors.initials: N
authors.lastname: Heine
authors.forename: Knut R
authors.initials: KR
authors.lastname: Asmis
authors.forename: Einar
authors.initials: E
authors.lastname: Uggerud
keywords: IR spectroscopy; carbon dioxide; magnesium; mass spectrometry; structure elucidation