Multidentate halogen-bond based catalysis: a computational study Nika Melnyk 1 , Marianne Rica Garcia 1 and Dr. Cristina Trujillo 1,2 1 Trinity College Dublin, Ireland, 2 University of Manchester, UK Organocatalysis, the use of small organic molecules in order to facilitate transformations, remains one of the most challenging topics in contemporary organic chemistry. The activation of substrates and reactants through organocatalysis is often classified into covalent and non-covalent catalysis. In the latter category, hydrogen bonding (HB) is the most well-established interaction. In the last years, the research field of σ-hole interactions is gaining increasing attention in the field of organocatalysis. 1-4 The name “σ-hole interactions” that is frequently used to describe these noncovalent forces was initially proposed by Clark, Murray, and Politzer in 2007, 5 and was chosen to reflect the relative position in elongation of σ-bonds.Inspired by the nature of the customary hydrogen bonding, halogen bonding (XB) is suggested to be a worthy alternative due to novel features such as its robust directionality. 1-4 The polarizability of the sigma hole of the XB-donor atom and the electronic effect of the attached organic framework have been explored computationally. The halogen atom (I, Br or Cl) in a symmetrical bidentate organocatalyst was varied and the mechanistic insights as well as the different non-covalent interactions (NCI) established in the Michael addition reaction upon complexation have been investigated by means of density functional theory (DFT). References 1. H. Yang and M. W. Wong, Molecules , 2020, 25 , 1045. A. M. Phillips, M. H. Prechtl and A. J. Pombeiro, Catalysts , 2021, 11 , 569. 2. V. Oliveira, M. Cardoso and L. Forezi, Catalysts , 2018, 8 , 605. M. Breugst and J. J. Koenig, European Journal of Organic Chemistry, 2020, 34 , 5473–5487. 3. T. Clark, M. Hennemann, J. S. Murray and P. Politzer, Journal of Molecular Modeling , 2006, 13 , 291–296.
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