Carboranylphosphines meet dendrimers: Electron-deficient scaffolds for ligand design and applications in catalysis
Recruting institution: CNRS.
Diploma-delivering institutions: UPS, ULEI.
Thesis co-directors: Anne-Marie Caminade (LCC, Toulouse, FR), Evamarie Hey-Hawkins (ULEI, Leipzig, DE)
Seondment hosts: BASF (DE), UAB (ES)
Objectives: Carboranyl phosphines and phosphites, for which the Hey-Hawkins group at ULEI is the expert, will be synthesized, based in particular on 1,2 or 1,7-dicarba-closo-dodecaborane(12) [ortho– or meta-carborane(12)], which are of interest as electron-poor backbones for phosphines. Due to the tunability of the steric and electronic properties of carboranyl phosphines, these ligands will be anchored to dendrimers, for which the Caminade group at LCC has vast expertise for specific applications. Recently, the two groups have jointly developed redox-switchable phosphines for redox-controlled catalysis. E. Hey-Hawkins et al., Boron Science, New Technologies and Applications, chapter 22, ed. N. S. Hosmane, CRC Press: Boca Raton, FL, USA, 2011, pp 513-559.  A.-M. Caminade, A. Ouali, R. Laurent, C.-O. Turrin, J.-P. Majoral, Coord. Chem. Rev.2016, 308, 478-497.  P. Neumann, H. Dib, A.-M. Caminade, E. Hey-Hawkins, ACIE 2015, 54, 311-314
Expected Results: We expect to obtain for the first time dendrimer-based electron-poor carboranylbisphosphines or mixed (hemilabile) carboranylphosphine-amines, ‑alkoxides, -thiols or -thioethers, etc. as ligands for challenging catalytic transformations, e.g. C–C coupling or C–H activation. The effects of different dendrimer structures and metals employed on the reactivity, activity, and selectivity of the catalysts will be studied, rationalized in collaboration with the theoretical group of Agustí Lledós (UAB) through secondment and applied for a rational design of improved catalysts. Decrease in the metal leaching will be particularly targeted, the objective being to reduce leaching below 1 ppm.