Activation Strain Analyses of Counterion and Solvent Effects on the Ion-Pair S 2 Reaction of and CH Cl.

We have computationally studied the bimolecular nucleophilic substitution (S 2) reactions of M NH + CH Cl (M  = Li , Na , K , and MgCl ; n = 0, 1) in the gas phase and in tetrahydrofuran solution at OLYP/6-31++G(d,p) using polarizable continuum model implicit solvation. We wish to explore and understand the effect of the metal counterion M and of solvation on the reaction profile and the stereochemical preference, that is, backside (S 2-b) versus frontside attack (S 2-f). The results were compared to the corresponding ion-pair S 2 reactions involving F and OH nucleophiles.

ExcelAutomat 1.3: Fragment analysis based on the distortion/interaction-activation strain model.

The distortion/interaction-activation strain model (D/I-ASM), a fragment analysis method, is applied to study the structure-reactivity relationship in reactions. The application of D/I-ASM involves the generation of input files for points along a reaction profile, submission of input files to a quantum software package, processing of parameters from the resulting output files and generation of graphical plots. The ExcelAutomat tool (Laloo et al.

Ion-Pair S 2 Reaction of OH and CH Cl: Activation Strain Analyses of Counterion and Solvent Effects.

We have theoretically studied the non-identity S 2 reactions of M OH +CH Cl (M =Li , Na , K , and MgCl ; n=0, 1) in the gas phase and in THF solution at the OLYP/6-31++G(d,p) level using polarizable continuum model (PCM) implicit solvation. We want to explore and understand the effect of the metal counterion M and solvation on the reaction profile and the stereoselectivity of these processes. To this end, we have explored the potential energy surfaces of the backside (S 2-b) and frontside (S 2-f) pathways.

ExcelAutomat: a tool for systematic processing of files as applied to quantum chemical calculations.

The processing of the input and output files of quantum chemical calculations often necessitates a spreadsheet as a key component of the workflow. Spreadsheet packages with a built-in programming language editor can automate the steps involved and thus provide a direct link between processing files and the spreadsheet. This helps to reduce user-interventions as well as the need to switch between different programs to carry out each step.

Ion-Pair SN 2 Substitution: Activation Strain Analyses of Counter-Ion and Solvent Effects.

The ion-pair SN 2 reactions of model systems MnF(n-1) +CH3Cl(M(+) =Li(+), Na(+), K(+), and MgCl(+); n=0, 1) have been quantum chemically explored by using DFT at the OLYP/6-31++G(d,p) level. The purpose of this study is threefold: 1) to elucidate how the counterion M(+) modifies ion-pair SN 2 reactivity relative to the parent reaction F(-) +CH3Cl; 2) to determine how this influences stereochemical competition between the backside and frontside attacks; and 3) to examine the effect of solvation on these ion-pair SN2 pathways. Trends in reactivity are analyzed and explained by using the activation strain model (ASM) of chemical reactivity.