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

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′-(N2-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.