Exploring and Exploiting Novel Unsupported TM-M' Heterobimetallic Complexes

The project builds upon recent work in the Whittlesey group that has led to the generation of novel heterobimetallic
complexes 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, the
e--deficient M' centre is embedded in a ligand scaffold. This reduces the level of coordinative unsaturation at both TM
and M', and makes it essentially impossible to differentiate cooperative effects from being (i) the action of both the
TM and M' in directly activating a substrate or (ii) M' acting indirectly (a 'fancy' ligand!) to tune the properties of the
TM centre, where all the reactivity occurs. Our systems therefore offer a new approach to this area of chemical
research. In one of our examples where there is a Ru-Zn bond, the coordinative unsaturation of the Ru and Zn
centres results in remarkable stoichiometric reactivity (H2 activation, dehydrocoupling of boranes) and, in a
preliminary proof of concept result, catalytic alkene hydrogenation. We will now explore the full potential of these
unsupported 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 our
unsupported 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 Professor
Stuart Macgregor at Heriot-Watt University, and we will also aim to exploit the disparate natures of TM and M' in a
way that exploits the Lewis acidity of M' to coordinate a Lewis base and the TM to bring about substrate activation
through collaboration with Professor Jonathan Williams here in chemistry at Bath. The project is ideal in nature for a
PhD student to develop skills in the manipulation of air-sensitive materials, learn the principles of catalysis and gain
exposure 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 research
interest. Thus, the student will receive exposure to leading researchers in model inorganic/organometallic chemistry.