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An isolable dicoordinatedialkylsilylene, 2,2,5,5-tetrakis(trimethylsilyl)silacyclopentane-1,1-diyl(6), was found to react with CO2and ArNCX(X = O, S) smoothly to give the corresponding bis(silyl)carbonate,4-imino-1,3-dioxasiletane and 4-imino-1,3-dithiasiletane derivativesin high yields, respectively. The molecular structures of these productswere determined by X-ray crystallography. All these reactions areparallel to those of a hypercoordinate silylene with η5-pentamethylcyclopentadienyl ligands, decamethylsilicocene, reportedby Jutzi et al. and are suggested to involve similarly the formationof the corresponding SiX doubly bonded compounds (X = O, S)at the initial steps. Mechanistic details of the multistep reactionof a model dialkylsilylene with CO2were investigated usingDFT calculations. [ABSTRACT FROM AUTHOR]

The active and well-designed Schiff base ligands are considered "privileged ligands". The so-called salen ligands, i.e., the tetradentate [O, N, N, O] bis-Schiff base ligands, have also found broad applications in many homogeneous catalytic reactions. Modification of the salen ligands has concentrated on altering the substituents in the phenolate rings and variations in the diamine backbones. Herein, o -carborane-supported salen ligands ( 2 ) were designed and prepared. A series of aluminum-salen complexes ( 3·(sol) 2 ), which were supported by the nido -C 2 B 9 carborane anions, were synthesized. These Al(III) complexes showed high activities (TOF up to 1500 h -1 ) in catalyzing the cycloaddition of epoxides and CO 2 at atmospheric pressure and near room temperature. Complexes 3·(sol) 2 are one of the rare examples of Al-based catalysts capable of promoting cycloaddition at 1 bar pressure of CO 2 . Density functional theory (DFT) studies combined with the catalytic results reveal that the catalytic cycles occur on two axial sites of the Al(III) center.

A one-pot, four-component annulation of 2,3,4,6-tetraarylpyridines from aromatic aldehydes, methyl ketones, diaryl ethanones, and ammonium acetate is described. The reaction features high functional group compatibility in air under solvent-free conditions without any additive and only water as the nontoxic byproduct, providing a strategy for the facile, economical, and eco-friendly construction of multiaryl-substituted pyridines from simple and readily available reactants.