New Insights on Carbon Dioxide Reactions with N, N'-dimethylethylenediamineThe use of Metal Organic Frameworks (MOFs) is becoming increasingly popular in the scientific community. These crystalline, three-dimensional, porous materials are composed of metal ions and organic ligands, and have been used for a wide variety of applications ranging from catalysis to gas separation and storage. One application that has piqued interest, due to the rising concerns about atmospheric pollutants, is Carbon Capture and Sequestration (CCS). Previous research performed by the Gagliardi group (U of M) in collaboration with the Long group (UC Berkeley) performed a DFT mechanistic study that tackled the capture of carbon dioxide (CO2) by N, N'�dimethylethylenediamine (mmen) anchored to the MOF Mg2-(dobpdc), where dobpdc2- is 4, 4'�dioxidobiphenyl-3, 3' �dicarboxylate) and explained the experimentally observed 1:1 (CO2 : amine) stoichiometry by an effective 2:2 stoichiometry yielding a bis-carbamic acid complex. CO2 capture by amines in aqueous media occurs through a 1:2 stoichiometry reaction, and the product consists of carbamate and ammonium adduct. Inside of the MOF, the corresponding intermediate species exists as neutral carbamic acid hydrogen bound to an amine. This work investigates the nature of carbamate-ammonium complex species in the gas phase for mmen derivate species containing different substituents. Such substituents include strong electron-withdrawing (EWG) and electron-donating (EDG) moieties like chlorine and oxygen, respectively, in addition to the standard methyl moiety so that the effects of changing substituents can be highly evident. It is expected that the EWG and EDG of most stable carbamate-ammonium species will be on the ammonium and carbamate adduct, respectively. However, thus far, with a net electrostatic energy of -662.4 kJ/mol, the most stable species contains a chlorine substituent on its ammonium adduct. Future perspectives of this project include exploration of the species with combinations of weak and strong EWG: EDG.

New insights on carbon dioxide reactions with N, N'-dimethylethylenediamine (mmen)

247th National Meeting (2014)

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