Simple and cheap steric and electronic characterization of the reactivity of Ru(II) complexes containing oxazoline ligands as epoxidation catalysts

The reactivity of a new family of complexes with general formula [Ru IV(T)(R-D)(O)]2+ (T = trispyrazolylmethane (tpm); D = N-(1-hydroxy-3-methylbutan-(2S)-(-)-2-yl)-(4S)-(-)-4-isopropyl-4, 5-dihydrooxazole-2-carbimidate, R = Bz (1); iPr (2)) has been analyzed. There is a significant difference in regioselectivity between the two catalysts in the epoxidation of 4-vinylcyclohexene; 1 leads to the regioselective oxidation at the ring alkene position, whereas 2 leads to the oxidation at the terminal position. Although computational calculations indicate small energy differences, both the geometry through steric maps and the electronic parameters of the reactants via conceptual DFT, or charges via NPA, explain the reactivity differences found for the catalysts depending on the substituents of the oxazoline ligands. © 2013 Elsevier B.V. All rights reserved.

Citation

Poater, A., Falivene, L., Cavallo, L., Llobet, A., Rodríguez, M., Romero, I., & Solà, M. (2013). Simple and cheap steric and electronic characterization of the reactivity of Ru(II) complexes containing oxazoline ligands as epoxidation catalysts. Chemical Physics Letters, 577, 142–146. doi:10.1016/j.cplett.2013.05.032

Sponsors

We acknowledge financial support from the MICINN of Spain (CTQ2007-60476/PPQ to I. R and M. R. and CTQ2011-23156/BQU to M. S.), the DIUE of the Generalitat de Catalunya (projects 2009SGR637 and Xarxa de Referencia en Quimica Teorica i Computacional), and the European Fund for Regional Development fund for the grant UNGI08-4E-003. M. S. is also grateful to the DIUE of the Generalitat de Catalunya for financial help through the ICREA Academia 2009 prize for excellence in research. A. P. thanks MICINN for a Ramon y Cajal contract (RYC-2009-05226), European Commission for a Career Integration Grant (CIG09-GA-2011-293900), and Generalitat de Catalunya (2012BE100824). Johnson & Matthey LTD are acknowledged for a RuCl<INF>3</INF>center dot nH<INF>2</INF>O loan. We also thank Centre de Supercomputacio de Catalunya (CESCA) for partial funding of computer time. The authors are extremely thankful for the helpful comments and assistance of Dr. Francesco Ragone.