Preparation and Molecular Structures of Tetrahydrofuran, Diethylene Diglycol Dimethyl Ether and 18‐Crown‐6 Complexes of Strontium and Barium Tetrahydridoborate

Abstract

AbstractThe strontium and barium tetrahydridoborate complexes M(BH4)2 · 2 diglyme and M(BH4)2 · 18‐crown‐6 (M = Sr, Ba) have been prepared from the solvates M(BH4)2 · 2 THF by ligand displacement. 11B‐NMR and IR data reveal strongly polar bonding of the BH4 groups to the metal centers, and X‐ray structural analyses of the diglyme and crown ether compounds show molecular units in which the BH4 group is in contact via three H atoms with the metal center. In contrast, M(BH4)2 · 2 THF compounds are chain polymers in the solid state, and each metal center is surrounded by 2 THF molecules in trans position and four BH4− groups each of which forms bridges with two metal centers. Estimations of the effective radius for the BH4 group indicate a high polarity for the M‐BH4 interaction.