Metal-Bound Sulfur and Selenium Sites as Halogen Bond Acceptors: The Supramolecular Association of Rhodium(I) Half-Lantern Complexes with 1,4-Diiodotetrafluorobenzene

The half-lantern Rh2I complexes trans-(Ch,N)-[Rh(μ-Ch∧N)(COD)]2 (Ch = S, Se; HCh∧N = 2-thiopyridine 1, 2-selenopyridine 2; COD = 1,5-cyclooctadiene) were cocrystallized with 1,4-diiodotetrafluorobenzene (1,4-FIB) to give isostructural cocrystals 1·1,4-FIB and 2·1,4-FIB, both studied by X-ray crystallography. The analysis of the structural data revealed a one-dimensional (1D) supramolecular arrangement, which is based on a poorly explored I···[Ch]–M halogen bonding. Density functional theory (DFT) calculations, using a set of complementary computational methods, closely interrogated these interactions and allowed the estimate of their energy (approximately −15 kcal/mol). In addition to the electrostatic and dispersion interaction components, the LP(Ch) → σ*(I–C) (LP = lone pair) charge transfer also noticeably contributes to the halogen bonding and provides some covalent character to this noncovalent interaction. The observed and studied assembly provides a route to supramolecular integration of metal-containing systems via ligand-involving halogen bonding, which include S or Se nucleophilic sites.