Redistribution reactions of heteroleptic barium iodide derivatives: Synthesis and structures of trans-BaI2(DME)(triglyme), cis-BaI2(DME)(tetraglyme) and [Ba(tetraglyme)2]I2 · C7H8

The reaction between BaI2 · 2H2O and NaHFIP [HFIP = OCH(CF3)2] in a 1:1 stoichiometry gave the heterometallic compound NaBaI2(HFIP)(H2O)(THF)0.5 (1). Attempts to recrystallize 1 in the presence of N- or O-donor ligands lead to redistribution reactions. Barium iodide adducts such as BaI2(DME)3 (2), trans-BaI2(DME)(triglyme) (3) and cis-BaI2(DME)(tetraglyme) (4) were isolated with DME as solvent. A similar behavior was observed for the reaction between BaI2 · 2H2O and NaTFA (TFA = O2CCF3) in a 1:1 stoichiometry in THF, and [Ba(tetraglyme)2]I2 · C7H8 (6) was isolated in the presence of excess tetraglyme. All compounds have been characterized by elemental analysis, IR and 1H NMR as well as single crystal X-ray studies for 3, 4 and 6. Compounds 3 and 4 are covalent adducts with eight- and nine-coordinate barium, respectively. Compound 6 is an ionic compound where two tetraglyme ligands wrap the 10-coordinate barium cation in a helical fashion. The presence of DME actually allows the coordination number of barium in the mixed-ligand adducts 3 and 4 to be tuned. The average Ba–O bond lengths (2.80 for 3 to 2.87 Å for 6) reflect the coordination number of the metal. The same observation is valid for the average Ba–I bond distance, 3.442 for 3 vs. 3.536 Å for 4.

The reactions between BaI2 · 2H2O and sodium hexafluoroisopropoxide or sodium trifluoroacetate in a 1:1 stoichiometry lead to heterometallic Na–Ba compounds. These undergo redistribution reactions in the presence of O-donor ligands affording barium iodide adducts such as trans-BaI2(DME)(triglyme), cis–BaI2(DME)(tetraglyme) and [Ba(tetraglyme)2]I2 · C7H8 which were characterized by analysis, FT-IR, NMR and X-ray diffraction.Figure optionsDownload as PowerPoint slide