ADT-Type [FeFe]-hydrogenase biomimics featuring monodentate phosphines: formation, structures, and electrocatalysis

To further develop the diiron subsite biomimics of [FeFe]-hydrogenases, two new diiron azadithiolate (adt) complexes Fe 2 ( μ -adt NPh )(CO) 5 (Ph 2 PX) (X = NHBu t , 1 and P(O)Ph 2 , 2 ) featuring monodentate phosphines were unexpectedly produced by the Me 3 NO-induced decarbonylating reactions of all-CO diiron precursor Fe 2 ( μ -adt NPh )(CO) 6 ( A , adt NPh = (SCH 2 ) 2 NPh) with different aminodiphosphines (Ph 2 P) 2 NR (R = Bu t and C 6 H 4 Cl- p ) in MeCN at ambient temperature. The as-obtained complexes 1 and 2 have been fully characterized by means of elemental analysis, FT-IR, ( 1 H, 31 P) NMR spectroscopies and further confirmed by X-ray crystallography. At the same time, the electrochemical and electrocatalytic behaviors of 1 and 2 have been studied and compared in the absence or presence of acetic acid (HOAc) as a proton source by cyclic voltammetry (CV), suggesting that they can be considered as the active biomimetic electrocatalysts for proton reduction to hydrogen (H 2 ).