From [2Mn2S] Diamond Cores to Butterfly Rhombs: Transformations That Highlight Alternating Peptide Binding Sites.

Thiocarboxamide chelates are known to assemble [2Mn2S] diamond core complexes via μ-S bridges that connect two Mn(CO) fragments. These can exist as and -isomers and interconvert via 16-electron, monomeric intermediates. Herein, we demonstrate that reduction of such Mn derivatives leads to a loss of one thiocarboxamide ligand and a switch of ligand binding mode from an O- to N-donor of the amide group, yielding a dianionic butterfly rhomb with a short Mn-Mn distance, 2.

Self-Assembled Nickel-4 Supramolecular Squares and Assays for HER Electrocatalysts Derived Therefrom.

Solid-state structures find a self-assembled tetrameric nickel cage with carboxylate linkages, [Ni(NS'O)I(CHCN)] ([]), resulting from sulfur acetylation by sodium iodoacetate of an [NiNS] dimer in acetonitrile. Various synthetic routes to the tetramer, best described from XRD as a molecular square, were discovered to generate the hexacoordinate nickel units ligated by NS, iodide, and two carboxylate oxygens, one of which is the bridge from the adjacent nickel unit in []. Removal of the four iodides by silver ion precipitation yields an analogous species but with an additional vacant coordination site, [], a cation but with coordinated solvent molecules.

Hemilabile Proton Relays and Redox Activity Lead to {FeNO} and Significant Rate Enhancements in NO Reduction.

Incorporation of the triad of redox activity, hemilability, and proton responsivity into a single ligand scaffold is reported. Due to this triad, the complexes Fe(PDI)(CO) (3) and Fe(PDI)(CO) (4) display 40-fold enhancements in the initial rate of NO reduction, with respect to Fe(PDI)(CO) (7). Utilizing the proper sterics and p K of the pendant base(s) to introduce hemilability into our ligand scaffolds, we report unusual {FeNO} mononitrosyl iron complexes (MNICs) as intermediates in the NO reduction reaction.

Uncoupled Redox-Inactive Lewis Acids in the Secondary Coordination Sphere Entice Ligand-Based Nitrite Reduction.

Metal complexes composed of redox-active pyridinediimine (PDI) ligands are capable of forming ligand-centered radicals. In this Forum article, we demonstrate that integration of these types of redox-active sites with bioinspired secondary coordination sphere motifs produce direduced complexes, where the reduction potential of the ligand-based redox sites is uncoupled from the secondary coordination sphere. The utility of such ligand design was explored by encapsulating redox-inactive Lewis acidic cations via installation of a pendant benzo-15-crown-5 in the secondary coordination sphere of a series of Fe(PDI) complexes.