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Insertion of Carbon Dioxide into Mg−N Bonds. Structural Characterization of a Previously Unknown η2 Chelation Mode to Magnesium in Magnesium Carbamates

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posted on 27.09.2004 by Yongjun Tang, Lev N. Zakharov, Arnold L. Rheingold, Richard A. Kemp
Insertion reactions of CO2 into magnesium amides that yield carbamates are known, and several different bonding modes of the −O2CNR2 moiety to magnesium have been previously identified. However, conspicuous by its absence is the simplest mode of chelation of the carbamate to a single Mg atom, the η2 chelating mode. We have now discovered that the insertion of CO2 into Mg2(NCy2)4 (Cy = cyclohexyl) in THF/HMPA (HMPA = hexamethylphosphoramide) forms the unsymmetrical dinuclear compound [Mg2(O2CNCy2)4(HMPA)] (1). X-ray diffraction analysis shows that 1 contains three different bonding modes of the carbamate to the Mg atoms, including the first example of the terminal bidentate η2 mode.