Effect of ligand modification on hydrogen production catalyzed by iron(III) complexes supported by amine-bis(phenolate) ligands

Abstract

In the presence of trimethylamine, the reaction of FeCl3 with 2-pyridylamino-N,N-bis(2-methylene-4-methyl-6-tert-butylphenol) (H2L) and 2-pyridylamino-N,N-bis(2-methylene-4-methoxyl-6-tert-butylphenol) (H2L′) produces two iron(III) complexes, [LFeCl] (1) and [L′FeCl] (2), respectively. 1 can electrocatalyze hydrogen evolution both from acetic acid, with a turnover frequency (TOF) of 98.5mol of hydrogen per mole of catalyst per hour at an overpotential (OP) of 941.6mV (in DMF), and from aqueous buffer solution (pH 7.0), with a TOF of 676.6mol of hydrogen per mole of catalyst per hour at an OP of 836.6mV. 2 electrocatalyzes hydrogen generation from acetic acid, with a TOF of 50.6mol of hydrogen per mole of catalyst per hour at an OP of 941.6mV, and from aqueous buffer solution (pH 7.0), with a TOF of 554mol of hydrogen per mole of catalyst per hour at an OP of 836.6mV. These results indicate that the electronic properties of the ligands play a vital role in determining the catalytic activities of the iron complexes.