Iridium(iii) hydrido complexes for the catalytic dehydrogenation of hydrazine borane

Abstract

The synthesis of 3,5-disubstituted cyclometalated iridium(III) hydrido complexes of the type [3,5-R₂(POCOP)IrHX] (3,5-R₂(POCOP) = κ³-C₅HR₂-2,6-(OPtBu₂)₂ with R = t-Bu, COOMe; X = Cl, H) is described. All complexes were investigated in the catalytic dehydrogenation of hydrazine borane and compared with the unsubstituted compounds [(POCOP)IrHX] (X = Cl, H). All catalysts are highly active and recyclable, clearly maintaining hydrogen production activity. The dehydrogenation products were structurally characterised by solid state NMR and FTIR spectroscopy. Experimental observations were complemented by a dispersion-corrected DFT study to rationalise the mechanism of hydrazine borane dehydrogenation.