title: Synthesis, structure, and electrocatalysis of diiron C-functionalized propanedithiolate (PDT) complexes related to the active site of [FeFe]-hydrogenases.
abstract: New C-functionalized propanedithiolate-type model complexes (1-8) have been synthesized by functional transformation reactions of the known complex [(mu-SCH2)2CH(OH)]Fe2(CO)6 (A). Treatment of A with the acylating agents PhC(O)Cl, 4-pyridinecarboxylic acid chloride, 2-furancarbonyl chloride, and 2-thiophenecarbonyl chloride in the presence of Et3N affords the expected C-functionalized complexes [(mu-SCH2)2CHO2CPh]Fe2(CO)6 (1), [(mu-SCH2)2CHO2CC5H4N-4]Fe2(CO)6 (2), [(mu-SCH2)2CHO2CC4H3O-2]Fe2(CO)6 (3), and [(mu-SCH2)2CHO2CC4H3S-2]Fe2(CO)6 (4). However, when A is treated with the phosphatizing agents Ph2PCl, PCl3 and PBr3, both C- and Fe-functionalized complexes [(mu-SCH2) 2CHOPPh2-eta1]Fe2(CO)5 (5), [(mu-SCH2) 2CHOPCl2-eta1]Fe2(CO)5 (6), and [(mu-SCH2) 2CHOPBr2-eta1]Fe2(CO)5 (7) are unexpectedly obtained via intramolecular CO substitution by P atoms of the initially formed phosphite complexes. The simplest C-functionalized model complex [(mu-SCH2) 2CO]Fe2(CO)6 (8) can be produced by oxidation of A with Dess-Martin reagent. While 8 is found to be an electrocatalyst for proton reduction to hydrogen, starting complex A can be prepared by another method involving the reaction of HC(OH)(CH2Br)2 with the in situ generated (mu-LiS) 2Fe2(CO)6. X-ray crystallographic studies reveal that the bridgehead C atom of 8 is double-bonded to an O atom to form a ketone functionality, whereas the bridgehead C atoms of A, 1, 3, and 4 are equatorially-bonded to their functionalities and those of 5-7 axially-bonded to their functionalities due to formation of the corresponding P-Fe bond-containing heterocycles.
authors.affiliation: Department of Chemistry, State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Tianjin, China. lcsong@nankai.edu.cn
authors.forename: Li-Cheng
authors.initials: LC
authors.lastname: Song
authors.forename: Chang-Gong
authors.initials: CG
authors.lastname: Li
authors.forename: Jie
authors.initials: J
authors.lastname: Gao
authors.forename: Bang-Shao
authors.initials: BS
authors.lastname: Yin
authors.forename: Xiang
authors.initials: X
authors.lastname: Luo
authors.forename: Xiao-Guang
authors.initials: XG
authors.lastname: Zhang
authors.forename: Hai-Lin
authors.initials: HL
authors.lastname: Bao
authors.forename: Qing-Mei
authors.initials: QM
authors.lastname: Hu
mesh_terms: D001665:Binding Sites; D040761:Biomimetic Materials / Q000737:chemistry; D002384:Catalysis; D004563:Electrochemistry; D006859:Hydrogen / Q000737:chemistry; D006864:Hydrogenase / Q000737:chemistry* / Q000378:metabolism; D007501:Iron / Q000737:chemistry*; D007506:Iron-Sulfur Proteins / Q000737:chemistry* / Q000378:metabolism; D011407:Propane / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry; D013438:Sulfhydryl Compounds / Q000138:chemical synthesis / Q000737:chemistry*
chemical_list: D007506:Iron-Sulfur Proteins; D013438:Sulfhydryl Compounds; C522648:propanedithiolate; D006859:Hydrogen; D007501:Iron; C118830:iron hydrogenase; D006864:Hydrogenase; D011407:Propane