Biomimetic models of [Fe]-hydrogenase featuring a 2-acylphenylthiomethyl-6-R-pyridine (R = H or OMe) ligand

Abstract

Despite a variety of [Fe]-H2ase models prepared so far, the structural and functional modeling study of the enzyme has remained a great challenge. Now, we report a new type of...

Structural and functional biomimetics of [Fe]-hydrogenase featuring a mono-, di- or tetrasubstituted pyridine ligand with a fac-C, N, and S ligation

“…The third step involves a new type of tandem reaction of the flexible pyridine ligand L 2 with NaI, Na 2 Fe(CO) 4 and iodine to give 1 and 2 in 55% and 32 models B/C reported by the Rose group 26,33 and models D reported by our group. 34…”

“…Such yields (64-95%) are the highest yields reported so far for the hydride transfer products catalyzed by the [Fe]-H 2 ase models. 33,34 Particularly, it is worth noting that complexes 2 and 6 are the first structural and functional [Fe]-H 2 ase models with a biomimetic fac-methylene C, pyridyl N, thioether S coordination mode prepared by the FPL-based method. Notably, a possible pathway for the H 2 activation and hydride transfer reactions catalyzed by a representative model 4 is proposed and particularly the existence of the highly unstable 5-coordinate intermediate M 4 and Fe-H species M 5 is proved by the isolation and characterization of their MeCN-and chloro-coordinated derivatives 7 and 8, respectively.…”

“…Fig.1Structural and functional model A reported by the Hu group, 32 models B/C reported by the Rose group26,33 and models D reported by our group 34. …”

“…The first step involves the nucleophilic substitution reaction of (ii) the intramolecular CO replacement by pyridyl N and thioether S atoms along with the intermolecular oxidativeaddition reaction of the resulting intermediate M 2 with iodine to afford target model 3 in 67% yield. 34 Having prepared the tridentate pyridine ligand-containing complex 3, we further found that it could undergo an intra- 6), Fe1-I1 2.7079(9), S1-Fe1-N1 83.60 (10), S1-Fe1-C2 178.17 (15), C15-Fe1-I1 177.13(13), N1-Fe1-I1 95.95 (10).…”

“…33 The third step includes the conversion of the transition state into the intermediate Fe-H species M 5 and cation [Et 3 NH] + . 33 The fourth step includes the hydride transfer from M 5 to imidazolium Im + to give imidazolidine Im-H 33,34 and regenerate 5-coordinate intermediate M 4 to complete the catalytic cycle.…”