Huangjie Lu, Yaxing Wang, Congzhi Wang, Lanhua Chen, Weiqun Shi*,Juan Diwu, Zhifang Chai,Thomas E. Albrecht-Schmitt and Shuao Wang*. "Two-Dimensional Inorganic Cationic Network of Thorium Iodate Chloride with Unique Halogen-Halogen Bonds" 2016 accepted
A unique 2D inorganic cationic network with the formula of [Th3O2(IO3)5(OH)2]Cl was synthesized hydrothermally. Its crystal structure can be best described as positively-charged slabs built with hexanuclear thorium clusters connected by iodate trigonal pyramids. Additional chloride anions are present in the interlayer spaces but surprisingly not exchangeable demonstrated by a series of CrO42- uptake experiments. This is because all chloride anions are trapped by multiple strong halogen-halogen interactions with short Cl-I bond lengths ranging from 3.134 to 3.333 Å, forming a special Cl-centered trigonal pyramid polyhedron as a newly observed coordination mode for halogen bonds. Density functional theory (DFT) calculations clarified that electron transformed from central Cl atoms to I atoms generating a halogen-halogen interaction energy with a value of about -8.3 kcal/mol per Cl…I pairs as well as providing a total value of -57.9 kcal/mol among delocalized halogen-halogen bonds, which is a new record value reported for a single halogen atom. Additional hydrogen bond interaction is also present between Cl…OH and the interaction energy is predicted to be -8.1 kcal/mol, confirming the strong total interaction to lock the interlayer Cl anions.
