High-resolution structural study on pyridin-3-yl ebselen and its N-methylated tosylate and iodide derivatives

The crystal structure of the pyridine-substituted benzisoselenazolinone 2-(pyridin-3-yl)-2,3-dihydro-1,2-benzoselenazol-3-one (C12H8N2OSe, 2), related to the antioxidant ebselen [systematic name: 2-phenyl-1,2-benzoselenazol-3(2H)-one, 1], is characterized by strong intermolecular N...Se( — N) chalcogen bonding, where the N...Se distance of 2.3831   (6)   Å is well within the sum of the van der Waals radii for N and Se (3.34   Å ). This strong interaction results in significant lengthening of the internal N — Se distance, consistent with significant population of the Se — N σ * antibonding orbital. Much weaker intermolecular O...Se chalcogen bonding occurs between the amide-like O atom in 2 and the less polarized C — Se bond in this structure. Charge density analysis of 2 using multipole refinement of high-resolution data allowed the electrostatic surface potential for 2 to be mapped, and clearly reveals the σ -hole at the extension of the Se — N bond as an area of positive electrostatic potential. Topological analysis of the electron-density distribution in 2 was carried out within the Quantum Theory of Atoms in Molecules (QTAIM) framework and revealed bond paths and (3, − 1) bond critical points (BCPs) for the N...Se — N moiety consistent with a closed-shell interaction; however, the potential energy term is suggestive of electron sharing. Analysis of the electron localization function (ELF) for the strong N...Se and the weak O...Se chalcogen-bonding ...
Source: Acta Crystallographica Section C - Category: Chemistry Authors: Tags: crystal structure chalcogen bonding hydrogen bonding multipole refinement electron density ebselen selenium research papers Source Type: research