Noncovalent Bonds, Spectral and Thermal Properties of Substituted Thiazolo[2,3-b][1,3]thiazinium Triiodides

Ekaterina Bartashevich,Irina Yushina,Dmitry Kim,Natalya Tarasova,Vladimir Sharutin

doi:10.3390/cryst9100506

Abstract

The interrelation between noncovalent bonds and physicochemical properties is in the spotlight due to the practical aspects in the field of crystalline material design. Such study requires a number of similar substances in order to reveal the effect of structural features on observed properties. For this reason, we analyzed a series of three substituted thiazolo[2,3-b][1,3]thiazinium triiodides synthesized by an iodocyclization reaction. They have been characterized with the use of X-ray diffraction, Raman spectroscopy, and thermal analysis. Various types of noncovalent interactions have been considered, and an S…I chalcogen bond type has been confirmed using the electronic criterion based on the calculated electron density and electrostatic potential. The involvement of triiodide anions in the I…I halogen and S…I chalcogen bonding is reflected in the Raman spectroscopic properties of the I–I bonds: identical bond lengths demonstrate different wave numbers of symmetric triiodide vibration and different values of electron density at bond critical points. Chalcogen and halogen bonds formed by the terminal iodine atom of triiodide anion and numerous cation…cation pairwise interactions can serve as one of the reasons for increased thermal stability and retention of iodine in the melt under heating.

Highlights

A great number of relatively strong noncovalent interactions in N- and S-heterocyclic polyiodides, such as halogen and chalcogen bonds, can promote the stability and diversity of possible polyiodide organization, but help in the organization of anion transport, chiral synthesis, and organocatalysis [1]
The development of noncovalent bond characterization in crystals includes the analysis of distribution features of the electrostatic potential [5], the quantum theory of atoms in molecules (QTAIM) methodology [6], electron localization function (ELF) [7], Laplacian of electron density [8], facilities of reduced density gradient (RDG) and analysis using the noncovalent interactions (NCI) method [9]
The type of noncovalent bonds were described on the basis of periodic quantum-chemical calculations revealing cation . . . anion chalcogen S . . . I bonds and halogen I . . . I bonds

Summary

Introduction

A great number of relatively strong noncovalent interactions in N- and S-heterocyclic polyiodides, such as halogen and chalcogen bonds, can promote the stability and diversity of possible polyiodide organization, but help in the organization of anion transport, chiral synthesis, and organocatalysis [1]. The development of noncovalent bond characterization in crystals includes the analysis of distribution features of the electrostatic potential [5], the quantum theory of atoms in molecules (QTAIM) methodology [6], electron localization function (ELF) [7], Laplacian of electron density [8], facilities of reduced density gradient (RDG) and analysis using the noncovalent interactions (NCI) method [9]. The chemistry of polyhalides has attracted particular attention due to the vast diversity of applicable properties related to the ability of halogens to form different types

Methods

Results

Conclusion