Amine Boranes Dehydrogenation Mediated by a Pyrazole-Based Unsymmetrical PCN Pincer Iridium(III) Hydride

Lightweight inorganic hydrides are at the forefront of contemporary chemical hydrogen storage research due to their easy handling, thermal stability and relatively high hydrogen content.1 Following our interest in developing new and efficient homogeneous catalysts for the dehydrogenation of amine-boranes mediated by transition metal hydride complexes,2 a new Ir(III) hydride species stabilized by a tridentate monoanionic unsymmetrical pincer ligand [(tBuPCN)]3 has been prepared and fully characterized. (tBuPCN)IrHCl has shown an improved catalytic performance with respect to its symmetrical analogue (tBuPCP)IrHCl2b at ambient temperature. The reaction of [(tBuPCN)IrHCl] with amine boranes in catalytic regimes have been studied through multinuclear (VT)-NMR and (VT)-IR spectroscopies, kinetic rate measurements and kinetic isotope effect (KIE) analysis. The results will be presented and discussed in details.