Synthesis and Reactivity of Iron Acyl Complexes Modeling the Active Site of [Fe]-Hydrogenase

摘要

[Fe]-hydrogenase, or H2-forming methylene-tetrahydrometha-nnopterin dehydrogenase (Hmd), is the third class of hydrogenase.n1nIt catalyzes the reduction of methenyl-tetrahydromethanopterinn(methenyl-H4MPT ) with H2 to form methylene-tetrahydrometha-nnopterin (methylene-H4MPT) and H .n2nThis is an intermediate stepnin the reduction of CO2 to methane by some methanogens, and itnoccurs likely through heterolytic H2 activation.n3nThe structure ofn[Fe]-hydrogenase, and especially its active site, has been sub-njected to extensive spectroscopic and structural studies.n4 8nThencurrent model suggests that the active site contains an iron centerncoordinated to a cysteine sulfur atom, two cis-CO ligands, anbidentate pyridone molecule through its nitrogen and acyl carbonnatoms, and a yet unidentified ligand (Figure 1).n6,7nThis active sitenis unique compared to those of [FeFe]- and [FeNi]-hydrogenases,n9nas it hosts a mono-Fe center and an unusual acyl-derivatizednpyridone cofactor.