molecular dynamics study of sodium NMR chemical shifts in the methylamine solution of [Na [2.2.2]cryptand Na].

The sodium anion (Na-) was once thought to behave like a 'genuine' anion, with both the [Ne] core and the 3s valence shell interacting very weakly with their environments. In the present work, following a recent study of the surprisingly small quadrupolar line widths of Na-, NMR shielding calculations were carried out for the Na-/Na+ [2.2.

Strategies for Evaluation of Rys Roots and Weights.

The Rys quadrature method for evaluating molecular integrals requires accurate numerical values of the nodes of a Rys polynomial and associated weight factors. The numerical value of a Rys polynomial for a specified value of its argument can be evaluated by three-term recursion using α and β coefficients. We review existing integration schemes for computing these recurrence parameters, discuss issues related to computational efficiency and numerical precision, and propose a slightly new integration method using Gauss-Rys quadrature.

Ionic Liquid Solvation versus Catalysis: Computational Insight from a Multisubstituted Imidazole Synthesis in [EtNH][HSO].

The mechanisms of a tetrasubstituted imidazole [2-(2,4,5-triphenyl-1 H-imidazol-1-yl)ethan-1-ol] synthesis from benzil, benzaldehyde, ammonium acetate, and ethanolamine in [EtNH][HSO] ionic liquid (IL) are studied computationally. The effects of the presence of the cationic and anionic components of the IL on transition states and intermediate structures, acting as a solvent versus as a catalyst, are determined. In IL-free medium, carbonyl hydroxylation when using a nucleophile (ammonia) proceeds with a Gibbs free energy (Δ) barrier of 49.