Synthesis, Structures, and Properties of Diiron Azadithiolate Complexes Containing a Subphthalocyanine Moiety as Biomimetic Models for [FeFe]-Hydrogenases

• Published in: European journal of inorganic chemistry 2013-05, Vol.2013 (14), p.2549-2557
• Main Authors: Song, Li-Cheng, Luo, Fei-Xian, Tan, Hao, Sun, Xiao-Jing, Xie, Zhao-Jun, Song, Hai-Bin
• Format: Article
• Language: English
• Subjects: Biomimetics; Derivatives; Enzyme models; Hydrogen production; Hydrogenases; Iron; Metalloenzymes; Precursors; Production methods; Subphthalocyanine; Sulfur; Synthesis; Toluene; X rays
• ISSN: 1434-1948; 1099-0682
• DOI: 10.1002/ejic.201300038

The first two model compounds for [FeFe]‐hydrogenases that contain a subphthalocyanine (SubPc) macrocycle, namely, [{(μ‐SCH2)2N(CH2)2CO2‐3‐C6H4S2C6H4‐3′‐O(SubPc)}Fe2(CO)6] (5) and [{(μ‐SCH2)2NC6H4‐4‐O(SubPc)}Fe2(CO)6] (8), have been synthesized and structurally characterized. The treatment of chlorosubphthalocyanine (SubPc‐Cl, 1) with (3‐HOC6H4S)2 in toluene gave the corresponding phenoxy‐substituted SubPc derivative 3‐HOC6H4S2C6H4‐3′‐O(SubPc) (2) in 78 % yield, whereas the reaction of in‐situ‐generated [(μ‐HOCH2S)2Fe2(CO)6] (3) with β‐alanine afforded diiron complex [{(μ‐CH2S)2N(CH2)2CO2H}Fe2(CO)6] (4) in 53 % yield. Further treatment of 2 with 4 in the presence of N,N′‐dicyclocarbodiimide (DCC) and N,N‐dimethyl‐4‐aminopyridine (DMAP) in CH2Cl2 resulted in the formation of model compound 5 in 86 % yield. Model compound 8 could be prepared by two methods. One method involves the reaction of in‐situ‐generated 3 with 4‐aminophenol in tetrahydrofuran (THF) to give diiron complex [{(μ‐CH2S)2NC6H4OH‐4}Fe2(CO)6] (6) in 61 % yield and further treatment of SubPc‐Cl (1) with 6 in toluene to give 8 in 13 % yield. The other method involves the reaction of SubPc‐Cl (1) with silver triflate (AgOTf) followed by treatment of the resulting intermediate SubPc‐OTf (7) with 6 in the presence of Et3N to produce 8 in a much higher yield (59 %). All the new precursors (2, 4, and 6) and the model compounds 5 and 8 have been fully characterized by elemental analysis and various spectroscopy techniques, as well by X‐ray crystallography for 2, 4, 6, and 8. In addition, the photoinduced H2 production catalyzed by model 8 was preliminarily investigated. Compounds 5 and 8 are the first model compounds for [FeFe]‐hydrogenases that contain a subphthalocyanine macrocycle. Their synthesis and characterization is reported.