The synthesis of acrylates from ethylene and CO2 has long been regarded as a dream reaction for the advantages of using CO2 as carbon source. The most challenging step in this reaction is the liberation of the acrylate species from the complex formed by insertion of ethylene and CO2. The first successful attempt to synthesize acrylates from Ni-lactones was achieved by Bruckmeier et al.[1] Recently, Lee et al[2] found ligand variation at nickelalactones has a significant influence on the yield of methyl acrylate. The best yield up to 56% was obtained from nickelalactone complex bearing tetramethylethylenediamine TMEDA ligand, while complexes with pyridine and 1,4-Bis(diphenylphosphino)butane DPPB do not show any selectivity to methyl acrylate. The understanding at molecular level of why different ligand causes drastically different activity and why high excess of MeI is needed is still missing. The calculation of sophisticated multidentate, sterically encumbering ligands however involves high computational costs.In order to accurately and efficiently model large ligands, we combine the XYG3 functional developed in Xu's group[3], one of the most reliable DFT method available for main group chemistry to the hybrid ONIOM method.The reaction pathways of nickelalactones bearing different ligands have been fully explored. For all studied complexes, the barrier to produce methyl acrylate is found to be only about 120 kJ/mol. However, changing ligands significantly affects the thermodynamic distribution of intermediates and thus causes very different selectivity to methyl acrylate. High excess of MeI is required to change the polarity of the solvent and suppress the side conversion to charge dissociated products.[1] Bruckmeier, C.; Lehenmeier, M. W.; Reichardt, R.; Vagin, S.; Rieger, B. Organometallics 2010, 29, 2199.[2] Lee, S. Y. T.; Cokoja, M.; Drees, M.; Li, Y.; Mink, J.; Herrmann, W. A.; K�hn, F. E. ChemSusChem 2011, 4, 1275.[3] Zhang, Y.; Xu, X.; Goddard, W. A. Proc. Natl. Acad. Sci. USA 2009, 106, 4963.

Ligand effects for the synthesis of acrylates from ethylene and CO<sub>2</sub> on Ni complexes: A theoretical study

247th National Meeting (2014)

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Ligand effects for the synthesis of acrylates from ethylene and CO2 on Ni complexes: A theoretical study

Ligand effects for the synthesis of acrylates from ethylene and CO₂ on Ni complexes: A theoretical study