Redistribution reactions of heteroleptic barium iodide derivatives: Synthesis and structures of trans-BaI 2(DME)(triglyme), cis-BaI 2(DME)(tetraglyme) and [Ba(tetraglyme) 2]I 2 · C 7H 8

Abstract

The reaction between BaI 2 · 2H 2O and NaHFIP [HFIP = OCH(CF 3) 2] in a 1:1 stoichiometry gave the heterometallic compound NaBaI 2(HFIP)(H 2O)(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 BaI 2(DME) 3 ( 2), trans-BaI 2(DME)(triglyme) ( 3) and cis-BaI 2(DME)(tetraglyme) ( 4) were isolated with DME as solvent. A similar behavior was observed for the reaction between BaI 2 · 2H 2O and NaTFA (TFA = O 2CCF 3) in a 1:1 stoichiometry in THF, and [Ba(tetraglyme) 2]I 2 · C 7H 8 ( 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.