Exploring Charge Redistribution at the Cu/CoSe Interface.

This study investigates the electronic interactions and charge redistribution at the dopant-support interface using a Cu/CoSe cluster construct. Specifically, the redox cluster series [CuCoSeL] ([-Cu]; = 0, -1, -2, -3; L = PhPNTol, Ph = phenyl, Tol = -tolyl) spanning four distinct oxidation states is synthesized and characterized using a multitude of techniques, including multinuclear NMR, UV-vis, XANES, and X-ray crystallography. Structural investigations indicate that the clusters are isostructural and chiral, adopting a pseudo- symmetry.

A Four-Coordinate Pr Imidophosphorane Complex.

The imidophosphorane ligand, [NPBu] (Bu=tert-butyl), enables isolation of a pseudo-tetrahedral, tetravalent praseodymium complex, [Pr(NPBu)] (1-Pr), which is characterized by a suite of physical characterization methods including single-crystal X-ray diffraction, electron paramagnetic resonance, and L-edge X-ray near-edge spectroscopies. Variable-temperature direct-current magnetic susceptibility data, supported by multiconfigurational quantum chemical calculations, demonstrate that the electronic structure diverges from the isoelectronic Ce analogue, driven by increased crystal field. The four-coordinate environment around Pr in 1-Pr, which is unparalleled in reported extended solid systems, provides a unique opportunity to study the interplay between crystal field splitting and spin-orbit coupling in a molecular tetravalent lanthanide within a pseudo-tetrahedral coordination geometry.

Tetravalent Cerium Alkyl and Benzyl Complexes.

High-valent cerium complexes of alkyl and benzyl ligands are unprecedented due to the incompatibility of the typically highly oxidizing Ce ion and the reducing alkyl or benzyl ligand. Herein we report the synthesis and isolation of the first tetravalent cerium alkyl and benzyl complexes supported by the tri--butyl imidophosphorane ligand, [NP(Bu)]. The Ce monoiodide complex, [CeI(NP(-butyl))] (), serves as a precursor to the alkyl and benzyl complexes, [Ce(Npt)(NP(-butyl))] () (Npt = neopentyl, CHC(CH)) and [Ce(Bn)(NP(-butyl))] () (Bn = benzyl, CHPh).

Coordination Modes and Binding Patterns in Lanthanum Phosphoramide Complexes.

A monoanionic phosphoramide ligand is introduced, which forms a series of lanthanum complexes with the ligand in both anionic and neutral forms. Stoichiometric control alone provides monometallic complexes with either two or three phosphoramide ligands. Alternatively, a combination of anionic and neutral proteo ligands featuring intramolecular hydrogen bonding can be obtained.

Structural distortion by alkali metal cations modulates the redox and electronic properties of Ce imidophosphorane complexes.

A series of Ce complexes with counter cations ranging from Li to Cs are presented. Cyclic voltammetry data indicate a significant dependence of the oxidation potential on the alkali metal identity. Analysis of the single-crystal X-ray diffraction data indicates that the degree of structural distortion of the secondary coordination sphere is linearly correlated with the measured oxidation potential.

Divergent Stabilities of Tetravalent Cerium, Uranium, and Neptunium Imidophosphorane Complexes.

The study of the redox chemistry of mid-actinides (U-Pu) has historically relied on cerium as a model, due to the accessibility of trivalent and tetravalent oxidation states for these ions. Recently, dramatic shifts of lanthanide 4+/3+ non-aqueous redox couples have been established within a homoleptic imidophosphorane ligand framework. Herein we extend the chemistry of the imidophosphorane ligand (NPC=[N=P Bu(pyrr) ] ; pyrr=pyrrolidinyl) to tetrahomoleptic NPC complexes of neptunium and cerium (1-M, 2-M, M=Np, Ce) and present comparative structural, electrochemical, and theoretical studies of these complexes.

Metal-Support Interactions in Molecular Single-Site Cluster Catalysts.

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 MCoSe(PEt)(L) (-M, M = Cr, Mn, Fe, Co, Cu, and Zn) was designed in which the active site (M)/support (CoSe) interactions are interrogated by systematically probing the electronic and structural changes that occur as the identity of the metal varies. All 3d transition metal -M clusters display remarkable catalytic activity for coupling tosyl azide and -butyl isocyanide, with Mn and Co derivatives showing the fastest turnover in the series.

Spectroscopic and electrochemical characterization of a Pr imidophosphorane complex and the redox chemistry of Nd and Dy complexes.

The molecular tetravalent oxidation state for praseodymium is observed in solution oxidation of the anionic trivalent precursor [K][Pr(NP(1,2-bis-Bu-diamidoethane)(NEt))] (1-Pr(NP*)) with AgI at -35 °C. The Pr complex is characterized in solution cyclic voltammetry, UV-vis-NIR electronic absorption spectroscopy, and EPR spectroscopy. Electrochemical analyses of [K][Ln(NP(1,2-bis-Bu-diamidoethane)(NEt))] (Ln = Nd and Dy) by cyclic voltammetry are reported and, in conjunction with theoretical modeling of electronic structure and oxidation potential, are indicative of principal ligand oxidations in contrast to the metal-centered oxidation observed for 1-Pr(NP*).

Inorganic clusters as metalloligands: ligand effects on the synthesis and properties of ternary nanopropeller clusters.

Redox-active multimetallic platforms with synthetically addressable and hemilabile active sites are attractive synthetic targets for mimicking the reactivity of enzymatic co-factors toward multielectron transformations. To this end, a family of ternary clusters featuring three edge metal sites anchored on a [Co6Se8] multimetallic support via amidophosphine ligands are a promising platform. In this report, we explore how small changes in the stereoelectronic properties of these ligands alter [Co6Se8] metalloligand formation, but also substrate binding affinity and strength of the edge/support interaction in two new ternary clusters, M3Co6Se8L6 (M = Zn, Fe; L(-) = Ph2PN(-)iPr).