Lanthanide polyoxocationic complexes: experimental and theoretical stability studies and Lewis acid catalysis.

The [ε-PMo(V)(8)Mo(VI)(4)O(36)(OH)(4){Ln(III)(H(2)O)}(4)](5+) (Ln=La, Ce, Nd, Sm) polyoxocations, called εLn(4), have been synthesized at room temperature as chloride salts soluble in water, MeOH, EtOH, and DMF. Rare-earth metals can be exchanged, and (31)P NMR spectroscopic studies have allowed a comparison of the affinity of the reduced {ε-PMo(12)} core, thus showing that the La(III) ions have the highest affinity and that rare earths heavier than Eu(III) do not react with the ε-Keggin polyoxometalate. DFT calculations provide a deeper insight into the geometries of the systems studied, thereby giving more accurate information on those compounds that suffer from disorder in crystalline form. It has also been confirmed by the hypothetical La→Gd substitution reaction energy that Ln ions beyond Eu cannot compete with La in coordinating the surface of the ε-Keggin molybdate. Two of these clusters (Ln=La, Ce) have been tested to evidence that such systems are representative of a new efficient Lewis acid catalyst family. This is the first time that the catalytic activity of polyoxocations has been evaluated.

Azepanone-based inhibitors of human cathepsin S: optimization of selectivity via the P2 substituent.

A series of azepanone inhibitors of cathepsin S is described. Selectivity over both cathepsin K and cathepsin L was achieved by varying the P2 substituent. Ultimately, a balanced potency and selectivity profile was achieved in compound 39 possessing a 1-methylcyclohexyl alanine at P2 and nicotinamide as the P' substituent. The cellular potency of selected analogs is also described.

Pd-containing organopolyoxometalates derived from Dawson polyoxometalate [P2W15V3O62]9⁻: Lewis acidity and dual site catalysis.

Grafting of a palladium complex to the Dawson vanadotungstate polyanion [P2W15V3O62](9-) via an organic ligand generates a large family of pincer-type hybrid polyoxometalates. The palladium-POM derivatives have dual catalytic properties. Unlike their parent inorganic polyanions, they catalyze allylations while retaining their oxidant character, which leads to single-pot dual site catalysis. This opens a new route for multicatalytic reactions.

Carbonyl-inserted organo-hybrids of a Dawson-type phosphovanadotungstate: scope and chemoselective oxidation catalysis.

The Dawson-type polyoxometalate (POM) [P(2)V(3)W(15)O(62)](9-) is a prototype for inclusion of carbonyls of amides, ureas, carbamates, and thiocarbamates into polyoxometallic structures. The carbonyl-inserted POMs catalyze the oxidation of sulfides. Chemoselectivity depends primarily on the proton content of the POM, but it is also influenced by the organic substituent.