Biomimetics of the [FeFe]-hydrogenase enzyme: Identification of kinetically favoured apical-basal [Fe2(CO)4(μ-H){κ2-Ph2PC(Me2)PPh2}(μ-pdt)]+ as a proton-reduction catalyst

The chelate complex dibasal [Fe2(CO)4{κ2-Ph2PC(Me2)PPh2}(μ-pdt)] protonates rapidly upon addition of HBF4 to yield apical-basal [Fe2(CO)4(μ-H){κ2-Ph2PC(Me2)PPh2}(μ-pdt)][BF4], which in acetonitrile catalyses proton reduction to dihydrogen at −1.58 V. DFT calculations have been used to study the mechanism and competing CECE and CEECC processes are uncovered, the branch point being the protonation or one-electron reduction of the 35-electron species [Fe2(CO)4(μ-H){κ2-Ph2PC(Me2)PPh2}(μ-pdt)].182