title: Structural models of the bimetallic subunit at the A-cluster of acetyl coenzyme a synthase/CO dehydrogenase: binuclear sulfur-bridged Ni-Cu and Ni-Ni complexes and their reactions with CO.
abstract: The Ni(II)-dicarboxamido-dithiolato complexes (Et4N)2[Ni(NpPepS)] (1) and (Et4N)2[Ni(PhPepS)] (2) were used as Nid metallosynthons in the construction of higher nuclearity dinuclear Ni-Cu and Ni-Ni species to model the bimetallic Mp-Nid site of the A-cluster of acetyl coenzyme A synthase/CO dehydrogenase (ACS/CODH). Reaction of 1 with [Cu(neo)Cl] and [Ni(terpy)Cl2] in MeCN affords the dinuclear complexes (Et4N)[Cu(neo)Ni(NpPepS)] (3) and [Ni(terpy)Ni(NpPepS)] (4), respectively. Reaction of 2 with [Ni(dppe)Cl2] in MeCN yields [Ni(dppe)Ni(PhPepS)] (6). The Ni-Cu complex 3 exhibits no redox chemistry at the Nid site and no reaction with CO. In contrast, the Nip sites in 4 and 6 are readily reduced (characterized by their Ni(I) EPR spectra) and bind CO, exhibiting nuco bands at 2044 and 1997 cm-1, respectively, indicating terminal CO binding. The present Ni-Ni systems replicate the structural and chemical properties of the A-cluster site in ACS/CODH and support the presence of Ni at Mp in the catalytically active enzyme.
authors.affiliation: Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA.
authors.forename: Todd C
authors.initials: TC
authors.lastname: Harrop
authors.forename: Marilyn M
authors.initials: MM
authors.lastname: Olmstead
authors.forename: Pradip K
authors.initials: PK
authors.lastname: Mascharak
mesh_terms: D000106:Acetate-CoA Ligase / Q000737:chemistry* / Q000378:metabolism; D000445:Aldehyde Oxidoreductases / Q000737:chemistry* / Q000378:metabolism; D040761:Biomimetic Materials / Q000737:chemistry / Q000378:metabolism; D002248:Carbon Monoxide / Q000737:chemistry* / Q000378:metabolism; D003300:Copper / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D009097:Multienzyme Complexes / Q000737:chemistry* / Q000378:metabolism; D009532:Nickel / Q000737:chemistry* / Q000378:metabolism; D009942:Organometallic Compounds / Q000737:chemistry / Q000378:metabolism
chemical_list: D009097:Multienzyme Complexes; D009942:Organometallic Compounds; D003300:Copper; D009532:Nickel; D002248:Carbon Monoxide; D000445:Aldehyde Oxidoreductases; C019823:carbon monoxide dehydrogenase; D000106:Acetate-CoA Ligase