Selective Construction of Trefoil knots and a Molecular Borromean Ring Induced by Steric Hindrance of Thioether Ligands.

Two Cp*-Rh based trefoil knots were obtained in high yield under ambient conditions via the coordination-driven self-assembly of semi-rigid thioether dipyridyl ligand 1,4-bis[(pyridin-4-ylthio)methyl]benzene (L ), ligand chloranilic acid (H -CA) and 6,11-dihydroxytetracene-5,12-dione (H -TtDo) with Cp*Rh metal corner units, respectively. Furthermore, using the bulkier 4,4'-{[(2,5-dimethyl-1,4-phenylene)bis(methylene)]bis(sulfanediyl)}dipyridine (L ) in the place of ligand L in the construction process resulted in the formation of a teranuclear metallacycle and a template-free Borromean ring in high yields thanks to significantly altered intermolecular forces between the constituent ligands induced by the sterically-hindering methyl groups of L , as demonstrated via a detailed X-ray crystallographic analysis and NMR spectroscopy.