Elucidating the mechanism of the halide-induced ligand rearrangement reaction.

The formation of heteroligated Rh(I) complexes containing two different hemilabile phosphinoalkyl ligands, (κ(2)-Ph(2)PCH(2)CH(2)S-Aryl)(κ(1)-Ph(2)PCH(2)CH(2)O-C(6)H(5))RhCl, through a halide-induced ligand rearrangement (HILR) reaction has been studied mechanistically. The half-life of this rearrangement reaction depends heavily on the Rh(I) precursor used and the chelating ability of the phosphinoalkyl thioether (PS) ligand, while the chelating ability of the phosphinoalkyl ether (PO) ligand has less of an effect. An intermediate complex which contains two PO ligands, (nbd)(κ(1)-Ph(2)PCH(2)CH(2)O-C(6)H(5))(2)RhCl (nbd = norbornadiene), converts to (nbd)(κ(1)-Ph(2)PCH(2)CH(2)O-C(6)H(5))RhCl resulting in a free PO ligand.

A coordination chemistry dichotomy for icosahedral carborane-based ligands.

Although the majority of ligands in modern chemistry take advantage of carbon-based substituent effects to tune the sterics and electronics of coordinating moieties, we describe here how icosahedral carboranes-boron-rich clusters-can influence metal-ligand interactions. Using a series of phosphine-thioether chelating ligands featuring meta- or ortho-carboranes grafted on the sulfur atom, we were able to tune the lability of the platinum-sulfur interaction of platinum(II)-thioether complexes. Experimental observations, supported by computational work, show that icosahedral carboranes can act either as strong electron-withdrawing ligands or electron-donating moieties (similar to aryl- or alkyl-based groups, respectively), depending on which atom of the carborane cage is attached to the thioether moiety.

Enzyme mimics based upon supramolecular coordination chemistry.

Recent advances in supramolecular coordination chemistry have allowed chemists to synthesize macromolecular complexes that exhibit various properties intrinsic to enzymes. This Review focuses on structures inspired by properties and functions observed in enzymes rather than precise models of enzyme active sites. These structures are synthesized using convergent, modular, and high-yielding coordination-chemistry-based methods, which allow one to tailor the size, shape, and properties of the resulting complexes.

Solvent and temperature induced switching between structural isomers of Rh(I) phosphinoalkyl thioether (PS) complexes.

To develop functional systems based on the weak-link approach (WLA), it is important to understand how solvent and ligand binding strength alter the coordination geometry of complexes formed from this method. A series of phosphinoalkyl thioether (PS) hemilabile ligands with varying electron donating abilities were synthesized and incorporated into homoligated Rh(I)(PS)2Cl complexes to help understand the effects of solvent and ligand binding strength on the preferred coordination modes. The switching between closed and semiopen structural isomers of these Rh(I)(PS)2Cl complexes was studied by variable temperature 31P NMR spectroscopy in different solvent mixtures of CH2Cl2 and tetrahydrofuran (THF) to obtain thermodynamic parameters (DeltaG(o), DeltaH(o), TDeltaS(o), and K(eq)).