Co(III) Complexes with Coordinated Carboxamido Nitrogens and Thiolato Sulfurs as Models for Co-Containing Nitrile Hydratase and Their Conversion to the Corresponding Sulfinato Species
- 31 December 1999
- journal article
- research article
- Published by American Chemical Society (ACS) in Inorganic Chemistry
- Vol. 39 (2), 357-362
- https://doi.org/10.1021/ic990794m
Abstract
Recent spectroscopic data suggest that the Co(III) site in Co-containing nitrile hydratase is ligated to carboxamido nitrogens and thiolato sulfurs and most possibly one or more of the bound thiolates exist as sulfenato and/or sulfinato groups. The absence of any Co(III) complex with such coordination makes it quite difficult to predict the reactivity of this kind of Co(III) site. In this paper, the Co(III) complexes of two designed ligands PyPepSH2 (1) and PyPepRSH2 (2) have been reported. The two complexes, namely, (Et4N)[Co(PyPepS)2] (3) and Na[Co(PyPepRS)2] (4) are the first examples of Co(III) complexes with carboxamido nitrogens and thiolato sulfurs as donors. The average Co(III)−Namido and Co(III)−S distances in these complexes lie in the range 1.90−1.92 and 2.22−2.24 Å, respectively. Reaction of H2O2 with both complexes readily affords Na[Co(PyPepSO2)2] (5) and Na[Co(PyPepRSO2)2] (6), species in which the thiolato sulfurs are converted to sulfinato (SO2) groups. Such conversion also occurs when solutions of 3 and 4 are exposed to dioxygen in the presence of activated charcoal. These reactions are clean and the S → SO2 transformation does not introduce significant changes in the metric parameters of these complexes. The reactivity of 3 and 4 indicates that the bound Cys-sulfurs around the biological Co(III) site could be oxidized to sulfinato groups.Keywords
This publication has 36 references indexed in Scilit:
- Oxidation of Metal-Bound Thiolato Sulfur Centers in Fe(III) and Co(III) Complexes with Carboxamido Nitrogens and Thiolato Sulfurs as Donors: Relevance to the Active Sites of Nitrile HydratasesInorganic Chemistry, 1999
- Syntheses, Structures, and Reactivities of Cobalt(III)−Alkylperoxo Complexes and Their Role in Stoichiometric and Catalytic Oxidation of HydrocarbonsJournal of the American Chemical Society, 1998
- Photoinduced DNA Cleavage Reactions by Designed Analogues of Co(III)−Bleomycin: The Metalated Core Is the Primary Determinant of Sequence SpecificityInorganic Chemistry, 1996
- Study of Sulfinate and Sulfenate Complexes Derived from the Oxygenation of Thiolate Sulfur in [1,5-Bis(2-mercapto-2-methylpropyl)-1,5-diazacyclooctanato(2-)]nickel(II)Journal of the American Chemical Society, 1995
- Nucleophilicity of coordinated chalcogens as evaluated in DMF-water mediaInorganic Chemistry, 1981
- Kinetics of oxidation of (cysteinato-N,S)bis(ethylenediamine)cobalt(III) and related thiolato complexes to sulfenatocobalt(III) complexesInorganic Chemistry, 1978
- Model for the binding of D-penicillamine to metal ions in living systems: synthesis and structure of L-histidinyl-D-penicillaminatocobalt(III) monohydrate, [Co(L-His)(D-Pen)].H2OJournal of the American Chemical Society, 1977
- Synthesis of a S-bonded sulfinic acid complex of cobalt(III) by an oxidative route. A structural trans effect in (2-sulfinatoethylamine-N,S)bis(ethylenediamine)cobalt(III) perchlorate nitrateInorganic Chemistry, 1976
- Oxidation of coordinated cysteine. Formation of sulfinato- and sulfenatocobalt(III) complexesInorganic Chemistry, 1975
- Catalytic Racemization of tris(Ethylenediamine)Cobalt(III) IonNature, 1960