This study provides atomistic insights into the interface between a single-site catalyst and a transition metal chalcogenide support and reveals that peak catalytic activity occurs when edge/ support redox cooperativity is maximized. A molecular platform MCo 6 Se 8 (PEt 3 ) 4 (L) 2 (1-M, M = Cr, Mn, Fe, Co, Cu, and Zn) was designed in which the active site (M)/support (Co 6 Se 8 ) interactions are interrogated by systematically probing the electronic and structural changes that occur as the identity of the metal varies. All 3d transition metal 1-M clusters display remarkable catalytic activity for coupling tosyl azide and tert-butyl isocyanide, with Mn and Co derivatives showing the fastest turnover in the series. Structural, electronic, and magnetic characterization of the clusters was performed using single crystal X-ray diffraction, 1 H and 31 P nuclear magnetic resonance spectroscopy, electronic absorption spectroscopy, cyclic voltammetry, and computational methods. Distinct metal/support redox regimes can be accessed in 1-M based on the energy of the edge metal's frontier orbitals with respect to those of the cluster support. As the degree of electronic interaction between the edge and the support increases, a cooperative regime is reached wherein the support can deliver electrons to the catalytic site, increasing the reactivity of key metal-nitrenoid intermediates.

Alkyne metathesis represents a rapidly emerging synthetic method that has shown great potential in small molecule and polymer synthesis. However, its practical use has been impeded by the limited availability of user-friendly catalysts and their generally high moisture/air sensitivity. Herein, we report an alkyne metathesis catalyst system that can operate under open-air conditions with a broad substrate scope and excellent yields. These catalysts are composed of simple multidentate tris(2-hydroxyphenyl)methane ligands, which can be easily prepared in multi-gram scale. The catalyst substituted with electron withdrawing cyano groups exhibits the highest activity at room temperature with excellent functional group tolerance (-OH, -CHO, -NO2, pyridyl). More importantly, the catalyst provides excellent yields (typically >90%) in open air, comparable to those operating under argon. When dispersed in paraffin wax, the active catalyst can be stored on a benchtop under ambient conditions without any decrease in activity for one day (retain 88% after 3 days). This work opens many possibilities for developing highly active user-friendly alkyne metathesis catalysts that can function in open air.

We demonstrate that allosteric effects and redox state changes can be harnessed to create a switch that selectively and reversibly regulates the coordination chemistry of a single site on the surface of a molecular cluster. This redox-switchable allostery is employed as a guiding force to assemble the molecular clusters Zn 3 Co 6 Se 8 L′ 6 (L′ = Ph 2 PN(H)Tol, Ph = phenyl, Tol = 4-tolyl) into materials of predetermined dimensionality (1- or 2-D) and to encode them with emissive properties. This work paves the path to program the assembly and function of inorganic clusters into stimuli-responsive, atomically precise materials.

Metal coordination complexes of the sterically hindered β-diketonate, 2,6-dimesitylbenzoyl pinacolone (esac), are reported for Co, Ni, Cu, and Zn.