Crystallographic and Computational Studies of Conformationally Controlled 1,3-Bis(benzo[b]selenophen-2-yl)thiourea by Chalcogen-Bonding Interactions

A single crystal of 1,3-bis(benzo[ b ]selenophen-2-yl)thiourea ( 1 ) was obtained from a mixed solvent of dimethyl sulfoxide (DMSO) and acetone, and its crystal structure was determined using X-ray diffraction (XRD) analysis. The crystallographic study revealed that 1 adopts a planar structure in the trans – trans conformation with an Se⋯S⋯Se arrangement by chalcogen-bonding interactions. A thiourea–DMSO solvate, comprising two molecules of 1 and four DMSO molecules, was formed within the asymmetric unit. This solvate crystallizes in the orthorhombic system with Pca 2₁ as the space group and is stabilized by N–H⋯O and C–H⋯O hydrogen-bonding interactions. Furthermore, the electronic nature of 1 was investigated using density functional theory (DFT) calculations, including natural bond orbital (NBO) analysis and reduced density gradient (RDG)-based non-covalent interaction (NCI) plot index analysis as well as QTAIM analysis, to confirm the presence of chalcogen-bonding interactions on both sides of the thiocarbonyl group. The structure of 1,3-bis(benzo[b]selenophen-2-yl)thiourea–DMSO solvate displays intramolecular Se⋯S⋯Se chalcogen-bonding interactions, as well as intermolecular N–H⋯O and C–H⋯O hydrogen-bonding interactions