Extended Assemblies of Ru(bpy)(CO)2X2 (X = Cl, Br, I) Molecules Linked by 1,4-Diiodotetrafluoro-Benzene (DITFB) Halogen Bond Donors

Abstract

The ruthenium carbonyl compounds, Ru(bpy)(CO)2X2 (X = Cl, Br or I) act as neutral halogen bond (XB) acceptors when co-crystallized with 1,4-diiodotetrafluoro-benzene (DITFB). The halogen bonding strength of the Ru-X···I halogen bonds follow the nucleophilic character of the halido ligand. The strongest halogen bond occurs between the chlorido ligand and the iodide atoms of the DITFB. All three halogen bonded complexes form polymeric assemblies in the solid state. In Ru(bpy)(CO)2Cl2·DITFB (1) and in Ru(bpy)(CO)2Br2·DITFB (2) both halido ligands are halogen bonded to only one DITFB donor. In Ru(bpy)(CO)2I2·DITFB (3) only one of the halido ligands is involved in halogen bonding acting as ditopic center for two DITFB donors. The polymeric structures of 1 and 2 are isomorphic wave-like single chain systems, while the iodine complexes form pairs of linear chains attached together with weak F···O≡C interactions between the closest neighbors. The stronger polarization of the iodide ligand compared to the Cl or Br ligands favors nearly linear C-I···I angles between the XB donor and the metal complex supporting the linear arrangement of the halogen bonded chain.