Microsolvated transition state models for improved insight into chemical properties and reaction mechanisms

Abstract

Over the years, several methods have been developed to effectively represent the chemical behavior of solutes in solvents. The environmental effects arising due to solvation can generally be achieved either through inclusion of discrete solvent molecules or by inscribing into a cavity in a homogeneous and continuum dielectric medium. In both these approaches of computational origin, the perturbations on the solute induced by the surrounding solvent are at the focus of the problem. While the rigor and method of inclusion of solvent effects vary, such solvation models have found widespread applications, as evident from modern chemical literature. A hybrid method, commonly referred to as cluster-continuum model (CCM), brings together the key advantages of discrete and continuum models. In this perspective, we intend to highlight the latent potential of CCM toward obtaining accurate estimates on a number of properties as well as reactions of contemporary significance. The objective has generally been achieved by choosing illustrative examples from the literature, besides expending efforts to bring out the complementary advantages of CCM as compared to continuum or discrete solvation models. The majority of examples emanate from the prevalent applications of CCM to organic reactions, although a handful of interesting organometallic reactions have also been discussed. In addition, increasingly accurate computations of properties like pK(a) and solvation of ions obtained using the CCM protocol are also presented.

Chemical synthesis of lactic acid from cellulose catalysed by lead(II) ions in water

“…The computational approach adopted in the current study has been verified to be practicable for chemical reactions in aqueous solutions 26,27 . Our computational results are displayed in Fig.…”

How Accurate is the SMD Model for Predicting Free Energy Barriers for Nucleophilic Substitution Reactions in Polar Protic and Dipolar Aprotic Solvents?

“…Yet another possibility before going to full explicit solvation method is the use of hybrid cluster-continuum approaches. 23,52,[63][64][65] Our group has successfully applied this model to some interesting ion-molecule reactions. 11,[66][67][68] The use of full explicit solvent molecules coupled with free energy perturbation was pioneered by Jorgensen, 69 and the rate acceleration effect was predicted for a classical S N 2 reaction.…”

“…Yet another possibility before going to full explicit solvation method is the use of hybrid cluster-continuum approaches. 23,52,[63][64][65] Our group has successfully applied this model to some interesting ion-molecule reactions. …”

A Study on the Condensation Reaction of 4-Amino-3,5-dimethyl-1,2,4-triazole with Benzaldehydes: Structure and Spectroscopic Properties of Some New Stable Hemiaminals

“…The calculations of zwitterion formation between methylamine and formaldehyde have been performed [40] and found that two water molecules reduce the reaction barriers of proton-transfer step [41]. As indicated in Table 4, the water role in the 2-nitro hemiaminal formation in acetonitrile solution is not restricted only to solvent effects [42], as water also acts as a reactive species. The catalytic properties of water molecules in this reaction were thought to be essential in order to facilitate the nucleophilic attack of the amine on the carbonyl group and the proton transfers from amine to water molecule and from water to aldehyde oxygen.…”