ESR3 Project

s-Block Metal-Mediated Hydroelementation

Recruting institution: UAB
Diploma-delivering institutions: UAB, FSU
Thesis co-directors: Agustí Lledós (UAB, Barcelona, ES), Matthias Westerhausen (FSU, Jena, DE)
Secondment host: Italmatch Chemicals (IT)

The addition of H-E bonds of amines (hydroamination), phosphanes (hydrophosphanylation), and phosphane oxides (hydrophosphorylation) to multiple bonds (e.g. alkynes) represents an atom-economic reaction that requires a catalyst. s-Block metal complexes are able to promote these addition reactions regioselectively with a significantly increased reactivity for heterobimetallic catalysts (e.g. mixed K/Ca complexes).[1] However, stereocontrol as well as steric and electronic control remain challenging tasks.[2] This project targets mechanistic studies to elucidate not only intermediates but obstacles during the catalytic H-E bond addition across unsaturated substrates to clarify the mode of action for the alkali and alkaline earth metalions.
Expected Results
Addition of H-E bonds across alkynes leads to E/Z-isomeric mixtures. In this project stereocontrol of the s-block metal-mediated addition of H-E-containing substrates onto alkynes with > 95 % of E– or Z-isomeric products will be achieved with catalyst loadings between 2-5 mol-%. Quantum chemical studies will allow to elucidate the influence of the nature of the s-block metal ions (charge, hardness, radius, polarizability) on the energy values of the transition states and hence on the mechanism of the catalytic cycle. We also envision a stereoselective intramolecular hydroelementation of alkenes with ee > 95 %.

[1] S. M. Härling, B. E. Fener, S. Krieck, H. Görls, M. Westerhausen, Organometallics2018, 37, 4380-4386. S. Ziemann, S. Krieck, H. Görls, M. Westerhausen, Organometallics2018, 37, 924-933. S. M. Härling, S. Krieck, H. Görls, M. Westerhausen, Inorg. Chem. 2017, 56, 9255-9263. F. M. Younis, S. Krieck, T. M. A. Al-Shboul, H. Görls, M. Westerhausen, Inorg. Chem. 2016, 55, 4676-4682.
[2] A. Couce-Rios, A. Lledós, G. Ujaque, Chem. Eur. J.2016, 22, 9311 – 9320.