Kinetics of sulfur-transfer from titanocene (poly)sulfides to sulfenyl chlorides: rapid metal-assisted concerted substitution.

The kinetics of sulfur transfer from titanocene (poly)sulfides (CpTiS, CpTiSCMe, CpTi(SAr), CpTiCl(SAr)) to sulfenyl chlorides (SCl, RSCl) have been investigated by a combination of stopped-flow UV-Vis/NMR reaction monitoring, titration assays, numerical kinetic modelling and KS-DFT calculations. The reactions are rapid, proceeding to completion over timescales of milliseconds to minutes, a sequence of two S-S bond-forming steps ( , ). The archetypical polysulfides CpTiS (1a) and CpTiSC(Me) (2a) react with disulfur dichloride (SCl) through rate-limiting intermolecular S-S bond formation ( ) followed by a rapid intramolecular cyclization ( , with ≫ [RSCl]).

Nickel-catalyzed ester carbonylation promoted by imidazole-derived carbenes and salts.

Millions of tons of acetyl derivatives such as acetic acid and acetic anhydride are produced each year. These building blocks of chemical industry are elaborated into esters, amides, and eventually polymer materials, pharmaceuticals, and other consumer products. Most acetyls are produced industrially using homogeneous precious metal catalysts, principally rhodium and iridium complexes.

Cytotoxicity of thiazolidinedione-, oxazolidinedione- and pyrrolidinedione-ring containing compounds in HepG2 cells.

Liver damage occurred in some patients who took troglitazone (TGZ) for type II diabetes. The 2,4-thiazolidinedione (TZD) ring in TGZ's structure has been implicated in its hepatotoxicity. To further examine the potential role of a TZD ring in toxicity we used HepG2 cells to evaluate two series of compounds containing different cyclic imides.

Bis-tropolonate complexes of tungsten: scaffolds for selective side-on binding of nitriles, imines and ketones.

The chiral bis-tropolonate tungsten(ii) tricarbonyl compound, (trop)2W(CO)3 (1), has been synthesized and structurally characterized. This seven-coordinate compound readily loses two carbonyl ligands to preferentially bind a series of π-bonding substrates to form six-coordinate complexes of the type (trop)2W(CO)(L). Alkynes coordinate strongly to form (trop)2W(CO)(η(2)-RCCR) (2) in which spectroscopic data is consistent with the alkyne serving as a 4-electron donor.

Carbon monoxide promoted reductive elimination of hydrogen from Tp' platinum complexes.

Acid-assisted reductive elimination of hydrogen from Tp'PtH(3) and of methane and hydrogen from Tp'PtMeH(2) (Tp' = hydridotris(3,5-dimethylpyrazolyl)borate) is examined herein. Loss of H(2) is observed from solutions containing platinum(IV) complexes of the type Tp'Pt(R)(H)(2) (R = Me, H) upon protonation and addition of a ligand such as CO. Results of kinetic studies on reductive elimination of H(2) and formation of [kappa(2)-(HTp')Pt(R)(L)][BAr'(4)] products from intermediates derived from Tp'Pt(R)(H)(2) precursors are described.