A new assembly of diiodine molecules at the 1,3-dimethylimidazole-2-thione (Me2ImS) template: crystal structure of (Me2ImS)2·(I2)5?

New Journal of Chemistry Pub Date: 2022-03-07 DOI: 10.1039/D2NJ00526C

Abstract

The new poly(I2) adduct [(Me2ImS)2·(I2)5] (Me2ImS = 1,3-dimethylimidazole-2-thione) has been synthesized and characterized by single crystal X-ray diffraction analysis. Units of [(Me2ImS)2·(I2)5] are located about a crystallographic inversion center, in which five diiodine molecules display interatomic contacts in a “head-to-tail” sequence giving a –(I2)5– chain interacting at each end with one Me2ImS molecule, CCDC 2133501. The S-bonding of Me2ImS to I2 is described as a donor–acceptor interaction in which I2 acts as an acceptor through the σ*(I–I) orbital resulting in an electronic charge transfer from the thioamide moiety. The bond distances d(S–I(1)) (2.504(2) ?) and d(I(1)–I(2)) (3.133(1) ?) are indicative of a strong interaction. Based on the S–I and I–I bond distances, the calculated values of the electronic charge densities, and the Raman spectral data, it is reasonable to represent the compound as an extended polarised system: [(Me2ImS)–I(1)]δ+?I(2)δ??I(3)–I(4)δ??(I(5)–I(5)a)?Iδ?–I?Iδ??[I-(Me2ImS)]δ+. The molecular electrostatic potential maps of the three adducts Me2ImS·I2, Me2ImS·I2·I2, and MeImHS·I2 (MeImHS = methimazole) have been reported to clearly identify the areas of charge increment (electron belt) and depletion (σ-hole), and thus the directionality of the noncovalent interactions.

Graphical abstract: A new assembly of diiodine molecules at the 1,3-dimethylimidazole-2-thione (Me2ImS) template: crystal structure of (Me2ImS)2·(I2)5
Recommended Literature