Synthesis of model compound of [FeFe]-hydrogenase active site is a promising and effective method to produce hydrogen. [mu-(SCH(CH2CH3)CH2S)-Fe-2(CO)(5)](2)-(kappa(1)-DPPE) (compound 1) and [mu-(SCH(CH2CH3)CH2S)] Fe-2(CO)(5) (kappa(1)-DPPM) (compound 2) were designed and synthesized. Compared 1 and 2 via IR, X-ray single crystal diffraction and CV, it was found that even through 1 and 2 shared similar electronic environment as well as crystal structure features, 1 with two symmetric [2Fe-2S] subsites had distinct reduction peaks and also showed higher electrocatalytic proton reduction efficiency in the presence of equivalent amount of HOAc, which indicated two symmetric [2Fe-2S] subsites played different roles in the process of proton reduction. Furthermore, -(kappa(1)-DPPE)2Fe-2S] moiety with variable valence state in 1 can mimic the [4Fe-4S] cluster and serve as an electron shuttle. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.