Assembly, Structure, and Reactivity of Cu₄S and Cu₃S Models for the Nitrous Oxide Reductase Active Site, Cu_Z*

Authors

Brittany J. Johnson, University of Illinois at Chicago
Sergey V. Lindeman, Marquette UniversityFollow
Neal P. Mankad, University of Illinois at Chicago

Document Type

Article

Language

eng

Format of Original

9 p.

Publication Date

2014

Publisher

American Chemical Society

Source Publication

Inorganic Chemistry

Source ISSN

0020-1669

Abstract

Bridging diphosphine ligands were used to facilitate the assembly of copper clusters with single sulfur atom bridges that model the structure of the Cu_Z* active site of nitrous oxide reductase. Using bis(diphenylphosphino)amine (dppa), a [Cu^I₄(μ₄-S)] cluster with N–H hydrogen bond donors in the secondary coordination sphere was assembled. Solvent and anion guests were found docking to the N–H sites in the solid state and in the solution phase, highlighting a kinetically viable pathway for substrate introduction to the inorganic core. Using bis(dicyclohexylphosphino)methane (dcpm), a [Cu^I₃(μ₃-S)] cluster was assembled preferentially. Both complexes exhibited reversible oxidation events in their cyclic voltammograms, making them functionally relevant to the Cu_Z* active site that is capable of catalyzing a multielectron redox transformation, unlike the previously known [Cu^I₄(μ₄-S)] complex from Yam and co-workers supported by bis(diphenylphosphino)methane (dppm). The dppa-supported [Cu^I₄(μ₄-S)] cluster reacted with N₃–, a linear triatomic substrate isoelectronic to N₂O, in preference to NO₂–, a bent triatomic. This [Cu^I₄(μ₄-S)] cluster also bound I–, a known inhibitor of Cu_Z*. Consistent with previous observations for nitrous oxide reductase, the tetracopper model complex bound the I– inhibitor much more strongly and rapidly than the substrate isoelectronic to N₂O, producing unreactive μ₃-iodide clusters including a [Cu₃(μ₃-S)(μ₃-I)] complex related to the [Cu₄(μ₄-S)(μ₂-I)] form of the inhibited enzyme.

Comments

Accepted version. Inorganic Chemistry, Vol. 53, No. 19 (2014): 10611-10619. DOI. © 2014 American Chemical Society. Used with permission.

Recommended Citation

Johnson, Brittany J.; Lindeman, Sergey V.; and Mankad, Neal P., "Assembly, Structure, and Reactivity of Cu₄S and Cu₃S Models for the Nitrous Oxide Reductase Active Site, Cu_Z*" (2014). Chemistry Faculty Research and Publications. 555.
https://epublications.marquette.edu/chem_fac/555