The Studies on Structure and Stability of CaB Clusters.

Calcium-boron systems have excellent properties of hardness, strength, and chemical stability, and we studied a series of CaB clusters to investigate their structures and relative stability. The results showed the most stable structures of CaB clusters are not planar. The B atoms tend to get together and form the planar ring to stabilize the structure, and the Ca atoms are coordinated to the periphery of the formations.

Insights into Ag(i)-catalyzed addition reactions of amino alcohols to electron-deficient olefins: competing mechanisms, role of catalyst, and origin of chemoselectivity.

The competing mechanisms of Ag(i)-catalyzed chemoselective addition reactions of amino alcohols and electron-deficient olefins leading to the -adduct or -adduct products were systematically studied with density functional theory methods. Calculations indicate that the AgHMDS/dppe AgOAc/dppe catalytic systems can play different roles and thereby generate two different products. The AgHMDS/dppe system works as a Brønsted base to deprotonate the amino alcohol OH to form the Ag-O bond, which leads to formation of the -adduct.

Density functional theory study on structure and stability of BeB clusters.

Rationale: Boride compounds hold promise for broad applications in the field of optoelectronics due to their high-temperature resistant, corrosion resistant and antioxidant properties. In order to reveal the formation mechanism of alkali and alkaline earth metal doped boron clusters, theoretical studies of these systems are required.

Methods: All the possible geometrical structures of BeB clusters (n = 1-8) were optimized at the B3LYP/6-311+G(d) level; the harmonic vibration frequencies were obtained to examine the true stability and give the zero-point vibration energy at that theoretical level.

Computational Characterization of the Origin of Selectivity in Cycloaddition Reactions Catalyzed by Phosphoric Acid Derivatives.

The mechanism of the organocatalyzed [4+2] cycloaddition of ο-hydroxybenzaldimines to 2,3-dihydro-2 H-furan (DHF) to form furanobenzopyrans has been investigated by using computational methods. Experiments have shown that this reaction produces different products (trans-fused or cis-fused) if different phosphoric acid derivatives are applied. Our study shows the reaction proceeds through a mechanism in which the imine re-arranges into an amine, which subsequently reacts with DHF with mediation from the catalyst.