An Experimental and Theoretical Insight into I₂/Br₂ Oxidation of Bis(pyridin‐2‐yl)Diselane and Ditellane

Abstract

The reactivity between bis(pyridin‐2‐yl)diselane oPy2Se2 and ditellane oPy2Te2 (L1 and L2, respectively; oPy = pyridyn‐2‐yl) and I2/Br2 is discussed. Single‐crystal structure analysis revealed that the reaction of L1 with I2 yielded [(HL1+)(I–)·5/2I2]∞ (1) in which monoprotonated cations HL1+ template a self‐assembled infinite pseudo‐cubic polyiodide 3D‐network, while the reaction with Br2 yielded the dibromide HoPySeIIBr2 (2). The oxidation of L2 with I2 and Br2 yielded the compounds HoPyTeIVI2 (3) and HoPyTeIIBr4 (6), respectively, whose structures were elucidated by X‐ray diffraction analysis. FT‐Raman spectroscopy measurements are consistent with a 3c‐4e description of all the X–Ch–X three‐body systems (Ch = Se, Te; X = Br, I) in compounds 2, 3, HoPyTeIIBr2 (5), and 6. The structural and spectroscopic observations are supported by extensive theoretical calculations carried out at the DFT level that were employed to study the electronic structure of the investigated compounds, the thermodynamic aspects of their formation, and the role of noncovalent s‐hole halogen and chalcogen bonds in the X···X, X···Ch and Ch···Ch interactions evidenced structurally.

1,4-Diiodotetrafluorobenzene 3,5-di-(pyridin-4-yl)-1,2,4-thiadiazole <1/1>

“…This interaction falls into the realm of halogen bonding because it involves a halogen atom acting as an electrophilic site and the lone pair of a pyridine nitrogen atom as a nucleophilic site [14][15][16]. Following our interest in the study of σ-hole interactions between halogen-rich compounds and pyridine tectons [17,18], we report here on the synthesis and characterization of the novel halogen-bonded 1:1 co-crystal (1) formed between L1 and 1,4-diiodotetrafluorobenzene (1,. In this halo-organic compound, the σ-hole effect for the iodide atoms is enhanced by the presence of the four electronegative fluorides, and numerous co-crystals formed by the halogen bonding between 1,4-DIFTB and pyridine donors can be found in the literature [14,[19][20][21][22][23].…”

Formation of extended polyiodides at large cation templates

“…In particular, FT-Raman spectroscopy confirms that extended polyiodides do not have distinctive vibrational properties other than those of perturbed (slightly elongated) I 2 molecules and symmetric/slightly asymmetric I 3 À . Perturbed I 2 molecules are characterized by only one strong band in the range 180-140 cm À 1 in the FT-Raman spectrum, the wavenumber depending on the extent of the I� � �I elongation; for linear and symmetric I 3 À , only the Raman-active symmetric stretch (� 1 ) occurs near 110 cm À 1 , while the antisymmetric stretch (� 3 ) and the bending deformation (� 2 ) are only IR-active (Aragoni et al, 2023b). The latter two modes also become Raman-active for slightly asymmetric I 3 À and they are found near 134 (� 3 ) and 80 cm À 1 (� 2 ), having medium and medium-weak intensities, respectively.…”