Controlling the Size of Molecular Copper Clusters Supported by a Multinucleating Macrocycle.

The use of a nonrigid, pyridyldialdimine-derived macrocyclic ligand (PDAI) enabled the synthesis of well-defined mono-, di-, tri-, and tetra-nuclear Cu(I) complexes in good yields through rational synthetic means. Starting from mono- and diargentous PDAI complexes, transmetalation to Cu(I) proceeded smoothly with formation of AgX (X = Cl, I) salts to generate mono-, di-, and trinuclear copper complexes. Monodentate supporting ligands (MeCN, xylNC, PMe, PPh) were found to either transmetallate with or bind various di- and trinuclear clusters.

Investigating Metal-Metal Bond Polarization in a Heteroleptic Tris-Ylide Diiron System.

This article describes the synthesis, characterization, and S-atom transfer reactivity of a series of -symmetric diiron complexes. The iron centers in each complex are coordinated in distinct ligand environments, with one (Fe) bound in a pseudo-trigonal bipyramidal geometry by three phosphinimine nitrogens in the equatorial plane, a tertiary amine, and the second metal center (Fe). Fe is coordinated, in turn, by Fe, three ylidic carbons in a trigonal plane, and, in certain cases, by an axial oxygen donor.

C-C σ-Bond Oxidative Addition and Hydrofunctionalization by a Macrocycle-Supported Diiron Complex.

This report describes the first examples of unassisted C(sp)-C(sp) and C(sp)-C(sp) bond oxidative addition reactions to give thermodynamically favorable products. Treatment of a diiron complex supported by a geometrically and electronically flexible macrocyclic ligand, (PDI)Fe(μ-N)(PPh) (), with stoichiometric amounts of various 4,4'-disubstituted diphenylacetylenes (Ar-C≡C-Ar; X = OMe, H, F, CF) yielded C(sp)-C(sp) bond oxidative addition products. When Ph-C≡C-R substrates were used as substrates (R = Me, Et, Pr, Bu), products of either C(sp)-C(sp) or C(sp)-C(sp) bond activation were obtained, with the less sterically encumbering alkynes exclusively undergoing C(sp)-C(sp) bond activation.

Oriented internal electrostatic fields: an emerging design element in coordination chemistry and catalysis.

The power of oriented electrostatic fields (ESFs) to influence chemical bonding and reactivity is a phenomenon of rapidly growing interest. The presence of strong ESFs has recently been implicated as one of the most significant contributors to the activity of select enzymes, wherein alignment of a substrate's changing dipole moment with a strong, local electrostatic field has been shown to be responsible for the majority of the enzymatic rate enhancement. Outside of enzymology, researchers have studied the impacts of "internal" electrostatic fields the addition of ionic salts to reactions and the incorporation of charged functional groups into organic molecules (both experimentally and computationally), and "externally" the implementation of bulk fields between electrode plates.