A new cumulene diiron complex related to the active site of Fe-only hydrogenases and its phosphine substituted derivatives: Synthesis, electrochemistry and structural characterization

摘要

A new cumulene diiron complex related to the Fe-only hydrogenase active site [(μ-SCH_2C(S)CCH_2)Fe_2(CO)_6] (1) was obtained by treatment of (μ-LiS)_2Fe_2(CO) _6 with excess 1,4-dichloro-2-butyne. By controllable CO displacement of 1 with PPh_3 and bis(diphenylphosphino)methane (dppm), mono- and di-substituted complexes, namely [(μ-SCH_2C(S)CCH _2)Fe_2(CO)_5L] (2: L = PPh_3; 3: L = dppm) and [(μ-SCH_2C(S)CCH_2)Fe_2(CO) _4L_2] (4: L = PPh_3; 5: L = dppm) could be prepared in moderate yields. Treatment of 1 with bis(diphenylphosphino)ethane (dppe) afforded a double butterfly complex [(μ-SCH2C(S)CCH 2)Fe2(CO)5]2(μ-dppe) (7). With dppm in refluxing toluene, a dppm-bridged complex [(μ-SCH_2C(S) CCH_2)Fe_2(CO)_4(μ-dppm)] (6) was obtained. These model complexes were characterized by IR, ~1H, ~(31)P NMR spectra and the molecular structures of 1, 2 and 5-7 were determined by single crystal X-ray analyses. The electrochemistry of 1-3 was studied and the electrocatalytic property of 1 was investigated for proton reduction in the presence of HOAc.