Example：10.1021/acsami.1c06204 or Chem. Rev., 2007, 107, 2411-2502
Inhibition of [FeFe]-hydrogenase by formaldehyde: proposed mechanism and reactivity of FeFe alkyl complexes Chemical Science (IF9.825), Pub Date : 2021-11-16, DOI: 10.1039/d1sc05803g Fanjun Zhang, Toby J. Woods, Lingyang Zhu, Thomas B. Rauchfuss
The mechanism for inhibition of [FeFe]-hydrogenases by formaldehyde is examined with model complexes. Key findings: (i) CH2 donated by formaldehyde covalently link Fe and the amine cofactor, blocking the active site and (ii) the resulting Fe-alkyl is a versatile electrophilic alkylating agent. Solutions of Fe2[(μ-SCH2)2NH](CO)4(PMe3)2 (1) react with a mixture of HBF4 and CH2O to give three isomers of [Fe2[(μ-SCH2)2NCH2](CO)4(PMe3)2]+ (+). X-ray crystallography verified the NCH2Fe linkage to an octahedral Fe(II) site. Although + is stereochemically rigid on the NMR timescale, spin-saturation transfer experiments implicate reversible dissociation of the Fe–CH2 bond, allowing interchange of all three diastereoisomers. Using 13CH2O, the methylenation begins with formation of [Fe2[(μ-SCH2)2N13CH2OH](CO)4(PMe3)2]+. Protonation converts this hydroxymethyl derivative to +, concomitant with 13C-labelling of all three methylene groups. The Fe–CH2N bond in + is electrophilic: PPh3, hydroxide, and hydride give, respectively, the phosphonium [Fe2[(μ-SCH2)2NCH2PPh3](CO)4(PMe3)2]+, 1, and the methylamine Fe2[(μ-SCH2)2NCH3](CO)4(PMe3)2. The reaction of [Fe2[(μ-SCH2)2NH](CN)2(CO)4]2− with CH2O/HBF4 gave [Fe2[(μ-SCH2)2NCH2CN](CN)(CO)5]− (−), the result of reductive elimination from [Fe2[(μ-SCH2)2NCH2](CN)2(CO)4]−. The phosphine derivative [Fe2[(μ-SCH2)2NCH2CN](CN)(CO)4(PPh3)]− (−) was characterized crystallographically.