Polymorphism, Halogen Bonding, and Chalcogen Bonding in the Diiodine Adducts of 1,3- and 1,4-Dithiane.

Timothy W. Hanks,Andrew J. Peloquin,William T. Pennington,Srikar Alapati,Colin D. McMillen

doi:10.3390/molecules26164985

Timothy W. Hanks, Andrew J. Peloquin + Show 3 more

Open Access

https://doi.org/10.3390/molecules26164985

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Abstract

Through variations in reaction solvent and stoichiometry, a series of S-diiodine adducts of 1,3- and 1,4-dithiane were isolated by direct reaction of the dithianes with molecular diiodine in solution. In the case of 1,3-dithiane, variations in reaction solvent yielded both the equatorial and the axial isomers of S-diiodo-1,3-dithiane, and their solution thermodynamics were further studied via DFT. Additionally, S,S’-bis(diiodo)-1,3-dithiane was also isolated. The 1:1 cocrystal, (1,4-dithiane)·(I2) was further isolated, as well as a new polymorph of S,S’-bis(diiodo)-1,4-dithiane. Each structure showed significant S···I halogen and chalcogen bonding interactions. Further, the product of the diiodine-promoted oxidative addition of acetone to 1,4-dithiane, as well as two new cocrystals of 1,4-dithiane-1,4-dioxide involving hydronium, bromide, and tribromide ions, was isolated.

Highlights

Halogen bonding, and the related chalcogen bonding, interactions occur due to an interaction between the electrophilic region on a halogen or chalcogen atom within a molecule and a nucleophilic region on a different atom [1,2,3,4]
The reaction of diiodine, one of the simplest halogen bond donors, with thioethers allows the concomitant study of halogen and chalcogen bonding, as well as the competition between the two
A common structural motif that emerges is the presence of an S···I halogen bond of varying strength, with a combination of halogen and chalcogen bonding to consolidate packing in the crystalline state

Summary

Introduction

The related chalcogen bonding, interactions occur due to an interaction between the electrophilic region on a halogen or chalcogen atom within a molecule and a nucleophilic region on a different atom [1,2,3,4] Due to their strength [5] and directionality [6], these interactions have emerged as useful tools in crystal engineering [7,8], pharmaceutical design [9,10,11], and in the understanding of synthetic transformations [12,13,14]. For 1,4-dithiane, the previously reported 1:1 cocrystal with I2 was isolated [15,23], as well as a new polymorph of S,S’bis(diiodo)-1,4-dithiane Each of these structures reveals an interplay between S···I halogen and chalcogen bonding. Molecules 2021, 26, 4985 oxidation of the compound to dioxides, revealing alternative reaction pathways in these halogen-containing systems

Results and Discussion

Materials

Thermal Analysis

Single-Crystal X-ray Analysis

Computational Study of 1 and 2

Synthesis of Cocrystals