title: First [Fe-NO](6) complex with an N(2)S(3)Fe-NO core as a model of NO-inactivated iron-containing nitrile hydratase. Are thiolates and thioethers equivalent donors in low-spin iron complexes?
abstract: The spectroscopic and structural properties of [(bmmp-TASN)FeNO]BPh(4) (1) (bmmp-TASN = 4,7-bis(2'-methyl-2'-mercaptopropyl)-1-thia-4,7-diazacyclononane) have been determined and are compared with the nitric oxide inactivated form of iron-containing nitrile hydratase, NHase(dark). [(bmmp-TASN)FeNO]BPh(4) is prepared from the addition of NO to (bmmp-TASN)FeCl followed by addition of sodium tetraphenylborate. [(bmmp-TASN)FeNO]BPh(4) crystallizes from acetonitrile-methanol solutions upon ether vapor diffusion as dark blue plates in the monoclinic space group P2(1)/c with a = 11.9521(14) A, b = 11.3238(13) A, c = 26.624(3) A, beta = 98.280(2), and Z = 4. The nu(NO) stretching frequency of 1856 cm(-)(1) and the Mössbauer parameters, delta = 0.06 mm/s and DeltaE(q) = 1.75 mm/s, compare favorably with those of NHase(dark). The similarities of the iron-sulfur bond distances to the thiolate, 2.284(2) A and 2.291(2) A, versus thioether, 2.285(2) A, are attributed to the low-spin configuration of the iron. The relationship between this structural observation and the spectroscopic properties of the complex are discussed.
authors.affiliation: Department of Chemistry, University of Louisville, Louisville, KY 40292, USA. grapperhaus@louisville.edu
authors.forename: Craig A
authors.initials: CA
authors.lastname: Grapperhaus
authors.forename: Apurba K
authors.initials: AK
authors.lastname: Patra
authors.forename: Mark S
authors.initials: MS
authors.lastname: Mashuta
mesh_terms: D001665:Binding Sites; D002384:Catalysis; D018360:Crystallography, X-Ray; D006836:Hydro-Lyases / Q000737:chemistry* / Q000378:metabolism; D058085:Iron Compounds / Q000737:chemistry* / Q000378:metabolism; D008024:Ligands; D008956:Models, Chemical; D008968:Molecular Conformation; D015394:Molecular Structure; D009569:Nitric Oxide / Q000737:chemistry*; D010084:Oxidation-Reduction; D013329:Structure-Activity Relationship; D013457:Sulfur Compounds / Q000737:chemistry* / Q000378:metabolism
chemical_list: D058085:Iron Compounds; D008024:Ligands; D013457:Sulfur Compounds; D009569:Nitric Oxide; D006836:Hydro-Lyases; C048831:nitrile hydratase