Evaluation of several economical computational methods for geometry optimization of phosphorus acid derivatives

DFT study of nano zinc/copper voltaic cells

To facilitate the development of new materials for use in batteries, it is necessary to develop ab initio full-electron computational techniques for modeling potential new battery materials. Here, we tested density functional theory procedures that are accurate enough to obtain the energetics of a zinc/copper voltaic cell. We found the magnitude of the zero-point energy correction to be 0.01-0.2 kcal/mol per atom or molecule and the magnitude of the dispersion correction to be 0.1-0.6 kcal/mol per atom or molecule for Zn _n , (H₂O) _n , [Formula: see text], [Formula: see text], and Cu _n . Counterpoise correction significantly affected the values of ∆[Formula: see text], ∆[Formula: see text], and ∆E^solv by 1.0-3.1 kcal/mol per atom or molecule at the B3PW91/6-31G(d) level of theory, but by only 0.04-0.4 kcal/mol per atom or molecule at the B3PW91/cc-pVTZ level of theory. The application of B3PW91/6-31G(d) yielded results that differed from macroscopic experimental values by 0.1-7.1 kcal/mol per atom or molecule, whereas applying B3PW91/cc-pVTZ produced results that differed from macroscopic experimental values by 0.1-4.8 kcal/mol per atom or molecule, with the smallest differences occurring for reactions with a small macroscopic experimental ∆E and the largest differences occurring for reactions with a large macroscopic experimental ∆E, implying size consistency.

Stereochemistry of internucleotide bond formation by the H-phosphonate method. 5. The role of Brønsted and H-bonding base catalysis in ribonucleoside H-phosphonate condensation-chemical and stereochemical consequences

Efficiency and stereoselectivity of condensations of ribonucleoside 3'-H-phosphonates with ethanol promoted by pivaloyl chloride were investigated as a function of tertiary amines used. Side reactions leading to an increased demand for the condensing agent were identified as derived from an attack of the pivalate anion at carbonyl centers of reactive pivaloyl derivatives. The conditions that secured quantitative yields of H-phosphonate diester condensations were assessed. Several tertiary amines promoted condensations with stereoselectivity higher than that observed for pyridine derivatives. A correlation between diastereoselectivity of the product formation and Brønsted and H-bonding basicities of the amine used was found.