Exploring and Exploiting Novel Unsupported TM-M' Heterobimetallic Complexes

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The project builds upon recent work in the Whittlesey group that has led to the generation of novel heterobimetalliccomplexes which feature unsupported bonds between a transition metal (TM) and a main group metal M' (M' = Zn/In/Ga/Li/Mg). Heterobimetallic complexes that combine an e--rich late transition metal centre with an e--deficient M'partner are attractive in that may confer two very different (potentially complementary) activities in catalytic reactions.While much international effort has gone into designing catalytically active TM-M' systems, in all of these cases, thee--deficient M' centre is embedded in a ligand scaffold. This reduces the level of coordinative unsaturation at both TMand M', and makes it essentially impossible to differentiate cooperative effects from being (i) the action of both theTM and M' in directly activating a substrate or (ii) M' acting indirectly (a 'fancy' ligand!) to tune the properties of theTM centre, where all the reactivity occurs. Our systems therefore offer a new approach to this area of chemicalresearch. In one of our examples where there is a Ru-Zn bond, the coordinative unsaturation of the Ru and Zncentres results in remarkable stoichiometric reactivity (H2 activation, dehydrocoupling of boranes) and, in apreliminary proof of concept result, catalytic alkene hydrogenation. We will now explore the full potential of theseunsupported TM-M' heterobimetallic complexes for both the stoichiometric and catalytic activation of small molecules.Initial targets will be to fully investigate catalytic alkene hydrogenation to establish catalyst efficiency, substrate scope(e.g. 'small' vs. 'bulky', terminal vs internal C=C bonds) and chemoselectivity (e.g. reduction of C=C vs C=O bonds).We will them aim to establish the limits of the TM/M' combination, as this is vital for showing the viability of ourunsupported bond methodology in a broader sense. This will involve variation of (i) both M' and the substituents on it,(ii ) the supporting ligands on TM (e.g. N-heterocyclic carbenes (NHCs) and phosphines (PR3)), (iii) the TM precursor(e.g. change of [Ru(NHC)2(CO)H]+ to [Ru(NHC)2(PR3)2H]+, [Ru(P-O-P)(PR3)H]+; change of LnRu to [Pt(NHC)2H]+, [Ir(NHC)2H2]+). The experimental work will be further supported by calculations in collaboration with ProfessorStuart Macgregor at Heriot-Watt University, and we will also aim to exploit the disparate natures of TM and M' in away that exploits the Lewis acidity of M' to coordinate a Lewis base and the TM to bring about substrate activationthrough collaboration with Professor Jonathan Williams here in chemistry at Bath. The project is ideal in nature for aPhD student to develop skills in the manipulation of air-sensitive materials, learn the principles of catalysis and gainexposure to modern spectroscopic and characterisation techniques (NMR spectroscopy, X-ray crystallography).Moreover, the target area to develop novel chemistry of heterobimetallic systems is a topic of worldwide researchinterest. Thus, the student will receive exposure to leading researchers in model inorganic/organometallic chemistry.