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 (.) 2H(2)O and NaHFIP [HFIP = OCH(CF3)(2)] in a 1:1 stoichiometry gave the heterometallic compound NaBaI2(HFlP)(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 (.) 2H(2)O and NaTFA (TFA = O2CCF3) in a 1:1 stoichiometry in THF, and [Ba(tetraglyme)(2)]I-2 (.) C7H8 (6) was isolated in the presence of excess tetraglyme. All compounds have been characterized by elemental analysis, IR and H-1 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 angstrom 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 angstrom for 4. (c) 2006 Elsevier Ltd. All rights reserved.