An unprecedented non-classical polyinterhalogen anion made of [I2Cl]− and I2 at the 2-(p-tolyl)selenopheno[2,3-b]pyridinium cation template

The reactivity between 2-(p-tolyl)selenopheno[2,3-b]pyridine (L) and ICl in MeCN is presented. Single crystal structure analysis revealed the formation of two distinct crystalline materials both featuring the protonated 2-(p-tolyl)selenopheno[2,3-b]pyridinium cation [HL]+. Colourless crystals were identified as the dihydrate salt [HL]Cl·2H2O (1), and dark-red crystals as compound {[HL]+[I2Cl]−}3·1/2I2 (2) that features the peculiar presence of the rare non-classical [I2Cl]− interhalide. Halogen Bonds (XBs) between the cocrystallized I2 molecule and [I2Cl]− anions led to the novel overall discrete [I10Cl4]4−H-shaped polyinterhalide formation, which is stabilized through hydrogen bonds (HBs) with the templating [HL]+ cations. The experimental observations are supported by extensive theoretical calculations at the DFT level that were employed to study the role played by non-covalent interactions in the formation of the presented unique polyinterhalide.