A new assembly of diiodine molecules at 1,3-Dimethylimidazole-2-thione (Me2ImS) template: Crystal Structure of (Me2ImS)2·(I2)5

Francesco Isaia

First

;Alessandra Garau

Second

;Maria Carla Aragoni;Massimiliano Arca;Claudia Caltagirone;Francesco Demartin;Vito Lippolis

Penultimate

;Tiziana Pivetta

Last

2022-01-01

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Abstract

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 given a –(I2)5– chain interacting at each end with one Me2ImS molecule, CCDC 2133501. The S-bonding of Me2ImS to I2 is described as donor-acceptor interaction in which I2 acts as acceptor through the *(I-I) orbital resulting in an electronic charge transfer from the thioamide moiety. The bond distances d(S-I(1)) (2.504(2) Å) and d(I(1)-I(2)) (3.133(1) Å) are indicative of a strong interaction. Based on the S-I, I-I bond distances, the calculated values of the electronic charge densities, and the Raman spectroscopy 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 (-hole), thus the directionality of noncovalent interactions.