Synthesis, characterization, and some properties of two types of new [Fe]-H2ase models containing a 4-phosphatopyridine or a 4-phosphatoguanosinepyridine moiety

Abstract

Two types of new [Fe]-H₂ase models were synthesized using well-designed synthetic methods. The first type of trisubstituted pyridine ligand-containing models [2-MeOCH₂-4-O₂P(OPh)₂-6-COCH₂C₅H₂N]Fe(CO)₂R (1, R = I; 2, R = EtS, 3, R = MeCOS), [2-MeOCH₂-4-O₂P(OPh)₂-6-COCH₂C₅H₂N]Fe(CO)₂(MeCN)BF₄ (4) and [2-MeOCH₂-4-O₂P(OPh)₂-6-COCH₂C₅H₂N]Fe(CO)(PPh₃)I (5) were synthesized on the basis of preparing the new trisubstituted pyridine precursors L₁–L₆, whereas the second type of pentasubstituted pyridine ligand-containing model [2-MeO-3,5-Me₂-4-OPO(OPh)O-5′-(N^2-iPrCO-2′,3′-O-CMe₂-guanosine)-6-COCH₂C₅N]Fe(CO)₂(η²-6-Me-2-SC₅H₃N) (6) was synthesized via the esterification reaction of a new phosphatoguanosine derivative L₇ with the corresponding pentasubstituted pyridine ligand-containing precursor (2-MeO-4-HO-3,5-Me₂-6-COCH₂C₅N)Fe(CO)₂(η²-6-Me-2-SCH₅H₃N) (D) in the presence of the dehydrating agent DCC. While all the new precursors L₁–L₇ and models 1–6 were fully characterized via elemental analysis and various spectroscopic techniques, the molecular structures of model 5 and precursor D were confirmed via X-ray crystallography. In addition, model 1 has been found to be a catalyst for proton reduction to H₂ from TFA under CV conditions.