title: A Model for the Active-Site Formation Process in DMSO Reductase Family Molybdenum Enzymes Involving Oxido-Alcoholato and Oxido-Thiolato Molybdenum(VI) Core Structures.
abstract: New bis(ene-1,2-dithiolato)-oxido-alcoholato molybdenum(VI) and -oxido-thiolato molybdenum(VI) anionic complexes, denoted as [Mo(VI)O(ER)L2](-) (E = O, S; L = dimethoxycarboxylate-1,2-ethylenedithiolate), were obtained from the reaction of the corresponding dioxido-molybdenum(VI) precursor complex with either an alcohol or a thiol in the presence of an organic acid (e.g., 10-camphorsulfonic acid) at low temperature. The [Mo(VI)O(ER)L2](-) complexes were isolated and characterized, and the structure of [Mo(VI)O(OEt)L2](-) was determined by X-ray crystallography. The Mo(VI) center in [Mo(VI)O(OEt)L2](-) exhibits a distorted octahedral geometry with the two ene-1,2-dithiolate ligands being symmetry inequivalent. The computed structure of [Mo(VI)O(SR)L2](-) is essentially identical to that of [Mo(VI)O(OR)L2](-). The electronic structures of the resulting molybdenum(VI) complexes were evaluated using electronic absorption spectroscopy and bonding calculations. The nature of the distorted O(h) geometry in these [Mo(VI)O(EEt)L2](-) complexes results in a lowest unoccupied molecular orbital wave function that possesses strong π* interactions between the Mo(d(xy)) orbital and the cis S(p(z)) orbital localized on one sulfur donor from a single ene-1,2-dithiolate ligand. The presence of a covalent Mo-S(dithiolene) bonding interaction in these monooxido Mo(VI) compounds contributes to their low-energy ligand-to-metal charge transfer transitions. A second important d-p π bonding interaction derives from the ∼180° O(oxo)-Mo-E-C dihedral angle involving the alcoholate and thiolate donors, and this contributes to ancillary ligand contributions to the electronic structure of these species. The formation of [Mo(VI)O(OEt)L2](-) and [Mo(VI)O(SEt)L2](-) from the dioxidomolybdenum(VI) precursor may be regarded as a model for the active-site formation process that occurs in the dimethyl sulfoxide reductase family of pyranopterin molybdenum enzymes.
authors.affiliation: Department of Material and Life Science, Division of Advanced Science and Biotechnology, Graduate School of Engineering, Osaka University , 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Hideki
authors.initials: H
authors.lastname: Sugimoto
authors.affiliation: Department of Material and Life Science, Division of Advanced Science and Biotechnology, Graduate School of Engineering, Osaka University , 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Masanori
authors.initials: M
authors.lastname: Sato
authors.affiliation: Comprehensive Analysis Center, The Institute of Scientific and Industrial Research (ISIR), Osaka University , 8-1 Mihogaoka, Ibaraki, Osaka 567-0057, Japan.
authors.forename: Kaori
authors.initials: K
authors.lastname: Asano
authors.affiliation: Comprehensive Analysis Center, The Institute of Scientific and Industrial Research (ISIR), Osaka University , 8-1 Mihogaoka, Ibaraki, Osaka 567-0057, Japan.
authors.forename: Takeyuki
authors.initials: T
authors.lastname: Suzuki
authors.affiliation: Picobiology Institute, Graduate School of Life Science, University of Hyogo, RSC-UH Leading Program Center , 1-1-1 Koto, Sayo-cho, Sayo-gun, Hyogo 678-0057, Japan.
authors.forename: Kaoru
authors.initials: K
authors.lastname: Mieda
authors.affiliation: Picobiology Institute, Graduate School of Life Science, University of Hyogo, RSC-UH Leading Program Center , 1-1-1 Koto, Sayo-cho, Sayo-gun, Hyogo 678-0057, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Ogura
authors.affiliation: Rigaku Corporation , Akishima, Tokyo 196-8666, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Matsumoto
authors.affiliation: Department of Chemistry and Chemical Biology, The University of New Mexico , MSC03 2060, 1 University of New Mexico, Albuquerque, New Mexico 87131-0001, United States.
authors.forename: Logan J
authors.initials: LJ
authors.lastname: Giles
authors.affiliation: Department of Chemistry and Chemical Biology, The University of New Mexico , MSC03 2060, 1 University of New Mexico, Albuquerque, New Mexico 87131-0001, United States.
authors.forename: Amrit
authors.initials: A
authors.lastname: Pokhrel
authors.affiliation: Department of Chemistry and Chemical Biology, The University of New Mexico , MSC03 2060, 1 University of New Mexico, Albuquerque, New Mexico 87131-0001, United States.
authors.forename: Martin L
authors.initials: ML
authors.lastname: Kirk
authors.affiliation: Department of Material and Life Science, Division of Advanced Science and Biotechnology, Graduate School of Engineering, Osaka University , 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Shinobu
authors.initials: S
authors.lastname: Itoh
mesh_terms: D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D007506:Iron-Sulfur Proteins / Q000737:chemistry*; D015394:Molecular Structure; D008982:Molybdenum / Q000737:chemistry*; D010088:Oxidoreductases / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet
chemical_list: D007506:Iron-Sulfur Proteins; D008982:Molybdenum; D010088:Oxidoreductases; C045664:dimethyl sulfoxide reductase
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