Unprecedented Reaction Mode of Phosphorus in Phosphinidene Rare-Earth Complexes: A Joint Experimental-Theoretical Study.

Reactions of trinuclear rare-earth metal complexes bearing functionalized phosphinidene ligand [L3Ln3(µ2-Me)2(µ3-Me)(µ3-η1:η2:η2-PC6H4-o)] (L = [PhC(NC6H4iPr2-2,6)2]-, Ln = Y (1a), Lu (1b)) with phenylacetylene, CO2, diisopropyl carbodiimide, isocyanide, or PhSSPh lead to the formation of a series of phosphorus-containing products. The reaction of 1 with CS2 yields two novel P-methyl-phosphindole-2,3-dithiolate dianion complexes, revealing an unusual tandem desulfurization/coupling/cyclization reaction mode of CS2. A possible reaction pathway was determined by density functional theory calculations. This emphasizes the key role of the reduction power of the formal P2- part of the phosphinidene in the C-S bond cleavage.

Reversing Conventional Reactivity of Mixed Oxo/Alkyl Rare-Earth Complexes: Non-Redox Oxygen Atom Transfer.

The preferential substitution of oxo ligands over alkyl ones of rare-earth complexes is commonly considered as "impossible" due to the high oxophilicity of metal centers. Now, it has been shown that simply assembling mixed methyl/oxo rare-earth complexes to a rigid trinuclear cluster framework cannot only enhance the activity of the Ln-oxo bond, but also protect the highly reactive Ln-alkyl bond, thus providing a previously unrecognized opportunity to selectively manipulate the oxo ligand in the presence of numerous reactive functionalities. Such trimetallic cluster has proved to be a suitable platform for developing the unprecedented non-redox rare-earth-mediated oxygen atom transfer from ketones to CS2 and PhNCS. Controlled experiments and computational studies shed light on the driving force for these reactions, emphasizing the importance of the sterical accessibility and multimetallic effect of the cluster framework in promoting reversal of reactivity of rare-earth oxo complexes.

Fractal MTW Zeolite Crystals: Hidden Dimensions in Nanoporous Materials.

Screw dislocation structures in crystals are an origin of symmetry breaking in a wide range of dense-phase crystals. Preparation of such analogous structures in framework-phase crystals is of great importance in zeolites but is still a challenge. On the basis of crystal-structure solving and model building, it was found that the two specific intergrowths in MTW zeolite produce this complex fractal and spiral structure. With the structurally determined parameters (spiral pitch h, screw angle θ, and spatial angle ψ) of Burgers circuit, the screw dislocation structure can be constructed by two different dimensional intergrowth sections. Thus the reported complexity of various dimensions in diverse crystals can be unified.

Catalyst-free dehydrative α-alkylation of ketones with alcohols: green and selective autocatalyzed synthesis of alcohols and ketones.

Direct dehydrative α-alkylation reactions of ketones with alcohols are now realized under simple, practical, and green conditions without using external catalysts. These catalyst-free autocatalyzed alkylation methods can efficiently afford useful alkylated ketone or alcohol products in a one-pot manner and on a large scale by CC bond formation of the in situ generated intermediates with subsequent controllable and selective Meerwein-Pondorf-Verley-Oppenauer-type redox processes.

Copper-catalyzed C-alkylation of secondary alcohols and methyl ketones with alcohols employing the aerobic relay race methodology.

By employing aerobic oxidation to aldehydes as a more effective alcohol activation strategy, ligand-free copper catalysts were found to be superior catalysts than other metals in aerobic dehydrative ß-alkylation of secondary alcohols and α-alkylation of methyl ketones using alcohols as the green alkylating reagents. Based on our mechanistic studies and also supported by the literature, we deduce that the newly-proposed relay race process rather than the conventional borrowing hydrogen-type mechanisms should be the most possible and a more rational mechanism for the aerobic C-alkylation reactions.

Copper-catalyzed N-alkylation of amides and amines with alcohols employing the aerobic relay race methodology.

By employing aerobic oxidation to aldehydes as a more effective alcohol activation strategy, we developed a green Cu-catalyzed N-alkylation method for various amides and amines with alcohols. This reaction is more advantageous than the literature methods for it uses a ligand-free copper catalyst, can be readily carried out under milder aerobic conditions and generates water as the only byproduct. More importantly, based on our mechanistic studies and also supported by the literature, rather than following the previously-proposed mechanisms, we deduce that the newly-proposed relay race process should be the most possible and a more rational mechanism for the reactions, especially under aerobic conditions.

Iron-catalyzed direct synthesis of imines from amines or alcohols and amines via aerobic oxidative reactions under air.

Abundant and cheap iron readily catalyzed the aerobic oxidative reactions of primary amines, secondary amines, benzylamines with anilines, and alcohols with amines by directly using air as the economic and safe oxidant, providing several direct, practical, and greener approaches for the preparation of useful imines.

Direct and mild palladium-catalyzed aerobic oxidative synthesis of imines from alcohols and amines under ambient conditions.

By ligand, TEMPO, and base screening, we developed a mild and green one-pot imine synthesis from alcohols and amines via a low-loading palladium-catalyzed tandem aerobic alcohol oxidation-dehydrative condensation reaction that can be readily carried out in open air at room temperature.