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-4(I)(mu(4)-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(dicydohexylphosphino)methane (dcpm), a [Cu-3(I)(mu(3)-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-4(I)(mu(4)-S)] complex from Yam and co-workers supported by bis(diphenylphosphino)methane (dppm). The dppa-supported [Cu-4(I)(mu(4)-S)] cluster reacted with N-3(-), a linear triatomic substrate isoelectronic to N2O, in preference to NO2-, a bent triatomic. This [Cu-4(I)(mu(4)-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 mu(3)-iodide clusters including a [Cu-3(mu(3)-S)(mu(3)-I] complex related to the [Cu-4(I)(mu(4)-S)(mu(2)-I)] form of the inhibited enzyme.