The research activities in our group are based on strong background in synthetic organometallic chemistry. Organometallic compounds, species that contain at least one metal-carbon bond, find application in many areas of knowledge including catalysis, energy chemistry, medicinal chemistry and chemical biology.
Ligand design is essential in the development of coordination and organometallic complexes, allowing their overall properties to be tuned and controlled in a precise manner. Our current research program focusses on the preparation of new organic ligands with different topologies and their coordination to transition metals for specific catalytic applications. Our final goal is to develop efficient and selective transformations and hence contribute to sustainable development.
I. Preparation of novel NHC-functionalised cyclopentadienyl ligands
We have disclosed the synthesis of N-Heterocyclic carbenes (NHCs) tethered to cyclopentadienyl ligands that we coordinated to a variety of metals (Mo, Ir, Rh, Ru). The new complexes showed interesting catalytic properties in a variety of catalytic reactions including transfer hydrogenation, amination of alcohols, isomerisation of allylic alcohols, and olefin epoxidation. This work has been done in collaboration with Prof. E. Peris from Universitat Jaume I in Spain.
A mini-review summarising this work has been recently published by us: Eur. J. Inorg. Chem. 2012, 1309.
II. Unprecedented synthesis of Fe-NHC complexes by C-H activation of imidazolium salts
We have prepared an iron-N-heterocyclic carbene (NHC) catalyst via C-H activation of an imidazolium salt with commercially available Fe3(CO)12. This advance precludes the requirement for the strong bases traditionally employed in the synthesis of similar complexes. Additionally, iron is an economically attractive metal for use in catalysis owing to its abundance and enviornmentally friendly nature. Using this catalyst, we have developed a mild and efficient catalytic system for reducing sulfoxides. Initial mechanistic probes suggest the existence of a free-radical base reaction pathway, although further studies are ongoing.
III. Well-defined nickel-NHC complexes as efficient catalytsts for the reduction of carbonyl groups
The reduction of carbonyl functionalities is an essential transformation in organic synthesis. To date, most of the catalytic systems developed for this reaction are based on precious metals. We have prepared the first example of a well-defined Ni-NHC complex catalysing the reduction of carbonyl groups. Mechanistic studies based on stoichiometric reactions, revealed that the nickel hydride complex is the active species in the reduction of carbonyl groups to alcohols.
IV. Designing robust catalysts for olefin epoxidation with hydrogen peroxide
In collaboration with researches from the University of Alcalá in Madrid we have developed a new class of robust titanium catalysts for the selective oxidation of olefins with aqueous hydrogen peroxide.
see in Inorg. Chem. 2012, 51, 6345.