Presentation Title

Effect of ligand sterics on N-heterocyclic carbene nickel nitrosyl complexes

Faculty Mentor

Dr. Sabine C.E. Stieber

Start Date

23-11-2019 8:45 AM

End Date

23-11-2019 9:30 AM

Location

234

Session

poster 2

Type of Presentation

Poster

Subject Area

physical_mathematical_sciences

Abstract

Nitrous oxide is a greenhouse gas with levels that are increasing due to human activity and fossil fuel combustion. Nitrous oxide has a warming potential 298 times that of carbon dioxide thus aiding in the deterioration of the ozone layer. Soil micro-organisms are able to reduce nitrous oxide into dinitrogen but are not able to counteract the quantity of nitrous oxide being produced. First row transition metals are used by soil micro-organisms to reduce N2O, so there is interest in generating new catalysts with earth abundant first row transition metals. Nickel complexes bound to bidentate N-heterocyclic carbene (NHC) ligands were synthesized to test feasibility for N2O or NO reduction. The NHC ligands were made by synthesizing mesitylimidazole and using it to make a bis(imidazolium)salt ligand precursor, [MesNHC2Me][Br]2. Following addition of KHMDS as a base, the free carbene ligand was reacted in the glovebox with Ni(COD)2 to form the nickel complex, (MesNHC2Me)Ni(COD), which was recently reported by our group and crystallographically characterized. Following synthesis of the nickel complex nitrosonium tetrafluoroborate and nitronium tetrafluoroborate were added to two variations of the nickel complexes, (MesNHC2Me)Ni(COD) and (DippNHC2Me)Ni(COD), to make nickel nitrosyl and nitrite complexes. These complexes were characterized by IR, 1H NMR and 13C NMR. The formation of nickel nitrosyl complexes can provide an insight of how ligand sterics may play a role for NO activation and reduction.

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Nov 23rd, 8:45 AM Nov 23rd, 9:30 AM

Effect of ligand sterics on N-heterocyclic carbene nickel nitrosyl complexes

234

Nitrous oxide is a greenhouse gas with levels that are increasing due to human activity and fossil fuel combustion. Nitrous oxide has a warming potential 298 times that of carbon dioxide thus aiding in the deterioration of the ozone layer. Soil micro-organisms are able to reduce nitrous oxide into dinitrogen but are not able to counteract the quantity of nitrous oxide being produced. First row transition metals are used by soil micro-organisms to reduce N2O, so there is interest in generating new catalysts with earth abundant first row transition metals. Nickel complexes bound to bidentate N-heterocyclic carbene (NHC) ligands were synthesized to test feasibility for N2O or NO reduction. The NHC ligands were made by synthesizing mesitylimidazole and using it to make a bis(imidazolium)salt ligand precursor, [MesNHC2Me][Br]2. Following addition of KHMDS as a base, the free carbene ligand was reacted in the glovebox with Ni(COD)2 to form the nickel complex, (MesNHC2Me)Ni(COD), which was recently reported by our group and crystallographically characterized. Following synthesis of the nickel complex nitrosonium tetrafluoroborate and nitronium tetrafluoroborate were added to two variations of the nickel complexes, (MesNHC2Me)Ni(COD) and (DippNHC2Me)Ni(COD), to make nickel nitrosyl and nitrite complexes. These complexes were characterized by IR, 1H NMR and 13C NMR. The formation of nickel nitrosyl complexes can provide an insight of how ligand sterics may play a role for NO activation and reduction.