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Keywords:

  • Enzyme models;
  • Iron;
  • Carb­onyl ligands;
  • Ligand substitution;
  • Selenium;
  • Sulfur

Abstract

Diiron carbonyl complex [{(μ-SCH2)2O}Fe2(CO)6] (A) reacted with Ph2PCl and Me3NO in MeCN at room temperature to give the expected and unexpected Ph2PCl-, Ph2PNMe2-, and Ph2PP(=O)Ph2-substituted complexes [{(μ-SCH2)2O}Fe2(CO)5L] [1, L = Ph2PCl; 2, L = Ph2PNMe2; 3, L = Ph2PP(=O)Ph2], whereas complex [{(μ-SCH2)2CH2}Fe2(CO)6] (B) reacted with Ph2PCl and Me3NO under similar conditions to afford only the unexpected complexes [{(μ-SCH2)2CH2}Fe2(CO)5L] [4, L = Ph2PNMe2; 5, L = Ph2PP(=O)Ph2]. Similarly, complex [{(μ-SeCH2)2O}Fe2(CO)6] (C) reacted with Ph2PCl and Me3NO in MeCN at room temperature to give the unexpected complexes [{(μ-SeCH2)2O}Fe2(CO)5L] [6, L = Ph2PNMe2; 7, L = Ph2PP(=O)Ph2], and the corresponding unexpected complexes [{(μ-SeCH2)2CH2}Fe2(CO)5L] [8, L = Ph2PNMe2; 9, L = Ph2PP(=O)Ph2] were produced by the reaction of complex [{(μ-SeCH2)2CH2}Fe2(CO)6] (D) with Ph2PCl and Me3NO under similar conditions. The structures of 19 were characterized by elemental analysis and spectroscopy, and for 15 and 79 by X-ray crystallography. Possible pathways for the formation of the functionalized phosphine-substituted complexes 19 have been suggested. Complexes 19 can be regarded as models for [FeFe] hydrogenases as their structures are similar to the active site of [FeFe] hydrogenases, and some have been found to be catalysts for proton reduction to hydrogen in the presence of HOAc.