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

• Main Authors: Xin Ding, Matti Tuikka, Kari Rissanen, Matti Haukka
• Format: Article
• Language: English
• Published: MDPI AG 2019-06-01
• Series: Crystals
• Subjects: halogen bond; ruthenium; crystal structure; bipyridine; carbonyl
• Online Access: https://www.mdpi.com/2073-4352/9/6/319
• ISSN: 2073-4352

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.