Theoretical interpretation of the role of the ionic liquid phase in the (R)-Ru-BINAP catalyzed hydrogenation of methylacetoacetate
Recently, the work focusing on the role of alkyl chain length in the N[R,222][Tf2N] ionic liquids and its reflection in the kinetic parameters of stereoselective hydrogenation of methylacetoacetate over (R)-[RuCl(binap)(p-cymene)]Cl complex was reported. Irregular trends in the principle parameter of enantioselectivity were observed. Here, a possible theoretical explanation of such irregular trends elucidated with the help of molecular simulations methods is presented. A stepwise approach is proposed for evaluating the energetically most stable conformers of a series of individual N[R,222][Tf2N] for the interpretation of selectivity-structure effects observed experimentally. Initially, Monte Carlo molecular mechanics was used followed by a semi-empirical PM3 method to elucidate also the characteristic thermodynamic functions of state and theoretical molecular spectra. The density functional theory was finally applied. The specific absolute entropy data revealed that due to the partition of the cation and anion twisted closer approach the ionic liquids N[8,222][Tf2N] and N[12,222][Tf2N] may stabilize the structures of the (R)-[RuCl(binap)(p-cymene)]Cl complex.
KeywordsIonic liquids Chiral catalysis Ru-BINAP complex DFT PM3 N[8,222][Tf2N] N[12,222][Tf2N]
Authors gratefully acknowledge the financial contribution of the Ministry of Industry and Trade of the Czech Republic, Project Grant No. FR-TI3/057. Academy of Sciences of the Czech Republic is also cordially acknowledged for supporting the bilateral CZ-UK cooperation project with Bangor University, UK.
- 4.Bartek L, Kluson P, Cerveny L (2005) Chem Listy 99:157Google Scholar
- 7.Zsigmond A, Notheisz F, Kluson P, Floris T (2010) In: Barbaro P, Liguori F (eds) Heterogenized homogeneous catalysts for fine chemicals production—catalysis by metal complexes, vol 34. Springer, BerlinGoogle Scholar
- 18.Allouche AR (2011) J Comp Chem 32(174):182Google Scholar
- 19.Halgren TA (1996) J Comp Chem 490:519Google Scholar
- 20.Hehre WJ (2003) A guide to molecular mechanics and quantum chemical calculations. Wavefunction Inc, IrvineGoogle Scholar
- 22.Frisch MJ et al (2003) Gaussian 03. Gaussian Inc, WallingfordGoogle Scholar
- 24.Parr RG, Yang W (1989) Density-functional theory of atoms and molecules. Oxford University Press, OxfordGoogle Scholar
- 31.Costa Gomes MF, Canongia Lopes JN, Padua AAH (2009) In: Kirchner B (ed) Ionic liquids—topics in current chemistry, vol 290. Springer, BerlinGoogle Scholar
- 32.Kirchner B (2009) In: Kirchner B (ed) Ionic liquids—topics in current chemistry, vol 290. Springer, BerlinGoogle Scholar