Synthetic and Structural Studies on a New Type of [Fe]‐Hydrogenase Mimics Each Containing One Hantzsch Ester Moiety

• Published in: European journal of inorganic chemistry Vol. 2020; no. 30; pp. 2862 - 2872
• Main Authors: Song, Li‐Cheng, Liu, Bei‐Bei, Xu, Kai‐Kai
• Format: Journal Article
• Language: English
• Published: WEINHEIM Wiley 16.08.2020; Wiley Subscription Services, Inc
• Subjects: Carbon monoxide; Carbonyl ligands; Chemistry; Chemistry, Inorganic & Nuclear; Crystallography; Dimers; Disubstituted pyridine precursors; Enzyme models; Hantzsch ester moiety; Hydrogenase; Inorganic chemistry; Iodine; Iron; Physical Sciences; Precursors; Science & Technology; ACTIVE-SITE MODELS; CRYSTAL-STRUCTURE; COMPLEXES; Iron; PORPHYRIN; Enzyme models; Carbonyl ligands; ACYLMETHYL(HYDROXYMETHYL)PYRIDINE; IRON-ONLY HYDROGENASES; DEHYDROGENASE; CLUSTER-FREE HYDROGENASE; BIOMIMETIC MODEL; Disubstituted pyridine precursors; Hantzsch ester moiety; LIGAND
• ISSN: 1434-1948; 1099-0682
• DOI: 10.1002/ejic.202000523

To develop the synthetic methodology for [Fe]‐H2ase models, a new type of the Hantzsch ester moiety‐containing [Fe]‐H2ase models (1–7) has been synthesized on the basis of preparing a series of new 2,6‐disubstituted pyridine precursors (L1–L10). Thus, the iodo models [2‐COCH2‐6‐(HEH)C5H3N]Fe(CO)2I (1), {2‐COCH2‐6‐[C6H4(HEH)]C5H3N}Fe(CO)2I (2), and {2‐COCH2‐6‐[Me(HEH)]C5H3N}Fe(CO)2I (3) could be prepared by reactions of precursors 2‐TsOCH2‐6‐(HEH)C5H3N (L2), 2‐TsOCH2‐6‐[C6H4(HEH)]C5H3N (L6), and 2‐TsOCH2‐6‐[Me(HEH)]C5H3N (L10) with Na2Fe(CO)4 followed by treatment of the resulting Fe(0) intermediates M1, M2 and M3 with iodine, respectively. In addition, further treatment of model 1 with AgOTf followed by reaction of the resulting Fe(II) intermediate M4 with MeCN gave the MeCN‐coordinated model {[2‐COCH2‐6‐(HEH)C5H3N]Fe(CO)2(MeCN)}(OTf) (4), whereas reaction of precursor L2 with Na2Fe(CO)4 followed by treatment of intermediate M1 with dimers (RCO2)2 afforded benzoato models [2‐COCH2‐6‐(HEH)C5H3N]Fe(CO)2(O2CR) (5, R = 4‐ClC6H4; 6, 2,6‐F2C6H3; 7, 2‐F3CC6H4). All the new precursors L1–L10 and models 1–7 were characterized by various spectroscopic methods and for some of them by X‐ray crystallography. A new type of [Fe]‐H2ase model, compounds 1–7, in which a simple [Fe]‐H2ase model skeleton is directly or indirectly bound to a well‐known hydride donor Hantzsch ester moiety, are prepared via a well‐designed multistep synthetic route. In addition, the spectroscopic analysis of 1–7 and particularly the X‐ray crystallographic study on 1–3 and 6 have confirmed that their structures are very similar to that of the active site of [Fe]‐H2ase.