An active, stable and recyclable Ru(II) tetraphosphine-based catalytic system for hydrogen production by selective formic acid dehydrogenation

Well-defined and in situ made RuIJII) complexes of the linear tetraphosphine ligand meso-1,1,4,7,10,10- hexaphenyl-1,4,7,10-tetraphosphadecane (tetraphos-1, P4) proved to be effective catalysts for selective formic acid dehydrogenation with good yields and TONs in the presence of an added amine, both under batch and continuous feed experimental conditions. The mechanism was studied by solution NMR and DFT calculations, highlighting the role of the trans-dihydrido complex [Ru(H)2(meso-P4)] as the active species in catalysis.