Synthesis, characterization, and some electrocatalytic properties of heteromultinuclear FeI/RuII Clusters

A series of new heteromultinuclear FeI/RuII clusters are described. The complexes (η6‐arene)RuFe2S2(CO)6 (arene = p‐cymene 1, C6Me6 2) and Fe2[μ‐S (Cp*Ru)(CO)2]2(CO)6 (Cp* = η5‐C5Me5) (3) were prepared by the reduction reactions of (μ‐S)2Fe2(CO)6 with 2 equiv of LiHBEt3, followed by treatment (μ‐SLi)2Fe2(CO)6 with ruthenium‐arene complexes Ru2(μ‐Cl)2Cl2(η6‐arene)2 or Cp*Ru (CO)2Cl in 22–33% yields. Further reactions of 1 and 2 with 1 equiv of triphenylphosphine in the presence of the decarbonylating agent Me3NO·2H2O, afforded the corresponding monophosphine‐substituted FeI/RuII complexes (η6‐arene)RuFe2S2(CO)5(Ph3P) (arene = p‐cymene 4, C6Me6 5) in 75% and 78% yields. While treatment of parent complex 1 or 2 with 1 equiv of diphosphine Ph2PCH2PPh2 (dppm) in xylene at reflux temperature resulted in the formation of the diphosphine‐bridged RuFe2S2(CO)9 derivate RuFe2S2(CO)7(dppm) (6). The possible pathway for the formation was proposed. Two isomers of novel macrocyclic complexes involve the (η6‐arene) Ru‐bridged quadruple‐butterfly Fe/S clusters [{μ‐S (CH2)3S‐μ}{(μ‐CS2)Fe2(CO)6}2]2[(η6‐arene)Ru]2 (arene = p‐cymene 7a and 7b, C6Me6 8a and 8b) were isolated by reactions of two μ‐CS2‐containing dianion [{μ‐S (CH2)3S‐μ}{(μ‐S=CS)Fe2(CO)6}2]2− with [Ru2(μ‐Cl)2Cl2(η6‐arene)2], in which the propylene groups are attached to two S atoms by ee and ea types of bonds respectively. All the new complexes 1–8 have been characterized by elemental analysis, spectroscopy, and particularly for 1–6, 7b and8a by X‐ray crystallography. In addition, the electrochemical properties of representative complexes 1–4 and 6 have been investigated. A series of novel heteromultinuclear FeI/RuII clusters are described. 7 and 8 are Ru‐bridged quadruple‐butterfly Fe/S macrocyclic complexes, which are shown to adopt novel stereochemistry due to axial‐equatorial disposition of the propylene group on sulfur. According to the results of electrochemical studies, 1‐4 has the ability to the electrocatalytic reduction of proton to dihydrogen.