title: Hexanickel enediolate cluster generated in an acireductone dioxygenase model reaction.
abstract: A nickel(II) enediolate cluster (2) forms upon treatment of [(6-Ph(2)TPA)Ni(PhC(O)C(OH)C(O)Ph)]ClO(4) (1) with Me(4)NOH x 5 H(2)O in CH(3)CN. Crystallographic studies of 2 revealed a hexanuclear structure of S(6) symmetry with a formula of {[Ni(PhC(O)C(O)C(O)Ph)(CH(3)OH)] x 1.33 CH(3)OH}(6). Because isolation of bulk amounts of 2 from the reaction involving 1 proved impossible, a solvation analogue of 2 (labeled 5) was generated from admixture of Ni(ClO(4))(2) x 6 H(2)O, 2-hydroxy-1,3-diphenylpropane-1,3-dione, and Me(4)NOH x 5 H(2)O in CH(3)OH/CH(3)CN. Complex 5 is formulated as {[Ni(PhC(O)C(O)C(O)Ph)(H(2)O)] x H(2)O x 0.25 CH(3)CN}(6) based on elemental analysis, a molecular weight determination, UV-vis, and a magnetic moment measurement. Treatment of 5 with O(2) and 6-Ph(2)TPA (6 equiv) results in the formation of CO and [(6-Ph(2)TPA)Ni(O(2)CPh)(2)(H(2)O)] (3), the latter of which was isolated in 69% yield. The level of (18)O incorporation in this reaction matches that for a reaction wherein 2 is generated from 1. These results provide evidence that a nickel(II) enediolate cluster is the O(2) reactive species in a previously reported model reaction for nickel(II)-containing acireductone dioxygenase.
authors.affiliation: Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322-0300, USA.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Rudzka
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Grubel
authors.forename: Atta M
authors.initials: AM
authors.lastname: Arif
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Berreau
mesh_terms: D056831:Coordination Complexes / Q000737:chemistry* / Q000378:metabolism*; D018360:Crystallography, X-Ray; D049308:Dioxygenases / Q000378:metabolism; D008954:Models, Biological; D008958:Models, Molecular; D009532:Nickel / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D056831:Coordination Complexes; D009532:Nickel; D049308:Dioxygenases; C083734:aci-reductone oxidase (CO-forming)