Title:	Participation of solvent in chemical reaction mechanisms via electrostatic and explicit solute-solvent interactions
DNr:	SNIC 2016/1-260
Project Type:	SNIC Medium Compute
Principal Investigator:	Timofei Privalov <priti@organ.su.se>
Affiliation:	Stockholms universitet
Duration:	2016-06-01 – 2016-12-01
Classification:	10407 10404 10405
Keywords:

Abstract

PURPOSE: to systematically investigate involvement of explicit solute-solvent interactions in chemical reaction mechanisms with the goal to narrow a gap between theory and reality of chemical reaction in solvent – we aim for long-term collaboration with experiment and therefore seek to increase employment of novel computational hardware architectures and novel quantum chemical software in order to systematically perform realistic simulations of chemical reactions with complex solute-solvent interactions via the transition path sampling in explicit solvent. Our immediate plans include in-depth computational investigations of a very important class of capture-reactions for CO2, N2O, CO, NO, and SO2 by a Lewis base (LB) plus a Lewis acid (LA), LB + LA + X → LB-X-LA, and solvent-assisted capture/activation of CO2 by non-metal LBs, LB + CO2 → LB-CO2. In 2015, we have reported first computational evidence of the two-step reaction-pathway which involves the dipolar Lewis complexes between tertiary phosphine and CO2, stabilized by environment (solvent) with apparent signs of dative phosphorus-carbon bonding. In 2009, we published results describing B(C6F5)3-catalyzed hydrogenation of ketones/aldehydes and suggesting for the first time that an FLP mechanism analogous to that for the related hydrogenation of imines (and hydrosilylation of carbonyl compounds) should be kinetically accessible. Our prediction was based on simplified (continuum) treatment of solvent. However, we suspected that solvent might take part explicitly in the reaction mechanism – for example, suitably basic solvent taking part in the proton transfer step. Our idea of B(C6F5)3-catalyzed hydrogenation of carbonyl compounds (C=O bonds) have sparked significant interest internationally and our intuition regarding direct involvement of solvent is now confirmed by experiment – recent publications by Stephan et al. and Ashley et al. Without going into details, the goal now is to investigate possible scenarios of solvent involvement including direct involvement of solvent in the proton-transfer step. This work will be done independently and in collaboration with experiment. Results of the previous project are published in Pu, M., Privalov, T., “Ab initio molecular dynamics with explicit solvent discovers a two-step pathway in the Frustrated Lewis Pair reaction”, Chem. Eur. J., 2015, 21, 17708; plus, we have a number of manuscripts in preparation for submission. January 26th, 2016, the PhD student Maoping Pu graduated – Maoping’s PhD thesis has ISBN 978-91-7649-298-7. New PhD student, Nils Lenart and a postdoc will continue this project onwards.