Emerging iridium complexes for further applications in hydrogen isotope exchange

Isotopic labelling with heavy hydrogen isotopes (D2 and T2 ) is widely used as a means to monitor the biological fate of a potential drug molecule.1 To circumvent additional synthetic steps in the drug design process, more direct, flexible, and selective means of introducing hydrogen isotopes continues to be the focus of considerable research attention. In relation to this, preliminary studies from our laboratory have allowed expedient access to a series of novel iridium complexes, many of which were previously inaccessible. By careful manipulation of the ligands supporting the iridium centre, these new catalysts can be applied under extremely mild reaction conditions and have now emerged to become some of the most active and, indeed, selective species known in this area of labelling chemistry.2 In a further extension to this overall programme of work, we are now using experimental and computational methods in parallel to optimise the design of our most successful catalysts. As a first step, investigations into the effect of changing the anionic portion of these complexes have been initiated to deliver complexes such as 2 (Scheme 1). This seemingly subtle adjustment of altering the catalyst counterion is now delivering unprecedented catalyst efficiency and, crucially, longevity. All studies to date will be delineated within this poster presentation.