ABSTRACT
An unprecedented synthetic approach has been devised to efficiently synthesize regioselective 1,4-disubstituted 1,2,3-triazoles. This technique relies on the use of innovative metal-free highly basic N-heterocyclic imino catalysts. The experimental observations have been supported further by TD-DFT computational studies.
ABSTRACT
In this article, we present a unique bimetallic paddle wheel copper(II) complex with the molecular formula [Cu2 C42 H54 N6 O8 ]. Several characterization tools have been employed to analyze this complex including single-crystal X-ray diffraction, HRMS, FTIR, and UV-vis spectroscopy. This copper(II) complex excels admirably as a catalytic system in parts-per-million level (ppm) loading for the azide-alkyne 'click' reaction under solvent-free conditions, allowing for the quantitative conversion of numerous 1,4-disubstituted 1,2,3-triazole. The specially designed coordinated ligand (perimidin-2-imine) in the Cu(II) complex accelerates the reaction rate significantly during the oxidative homocoupling reaction (OHC) and acts as a base for Cu-coordinated alkyne deprotonation. It has been demonstrated that the catalyst loading of 2.5â ppm is adequate to catalyze the cycloaddition of benzyl azide to phenylacetylene, leading to the extremely high turnover number of 120000 and a turnover frequency of 5000â h-1 . Synergistic evidence from stoichiometric reactions and experimental results provides insights into the plausible mechanism for the reaction. Each copper atom contributes to the outcome of the proposed reaction, one by bonding to the acetylide and the other by activating the azide as part of a bimetallic synergistic pathway.
ABSTRACT
In the last decade, major conceptual advances in the chemistry of actinide molecules and materials have been made to demonstrate their distinct reactivity profiles as compared to lanthanide and transition metal compounds, but some difficult questions remain concerning the intriguing stability of low-valent actinide complexes, and the importance of the 5f-orbitals in reactivity and bonding. The imidazolin-2-iminato moiety has been extensively used in ligands for the advancement of actinide chemistry owing to its unique capability of stabilizing the reactive and highly electrophilic metal ions by virtue of its strong electron donation and steric tunability. The current review article describes recent developments in the chemistry of light actinide metal ions (thorium and uranium) bearing these N-heterocyclic iminato moieties as supporting ligands. In addition, the effect of ring expansion of the N-heterocycle on the catalytic aptitude of the organoactinides is also described herein. The synthesis and reactivity of actinide complexes bearing N-heterocyclic iminato ligands are presented, and promising apposite applications are also presented. The current review focuses on addressing the catalytic behavior of actinide complexes with oxygen-containing substrates such as in the Tishchenko reaction, hydroelementation processes, and polymerization reactions. Actinide complexes have also found new catalytic applications, as demonstrated by the potent chemoselective carbonyl hydroboration and tandem proton-transfer esterification (TPTE) reaction, featuring coupling between an aldehyde and alcohol.
