Metalltetrahydridoborate und Tetrahydridoborato-metallate, 12 [1] Zur Kenntnis von Calcium-bis(tetrahydridoborat)-bis(dimethylglykolether)/Metal Tetrahydroborates and Tetrahydroborato Metalates, 12 [1] On Calcium Bis(tetrahydroborate)-bis(dimethylglycolether)

Abstract

Ca(BH4)2·2(CH3OCH2CH2OCH3)2, (1) has been prepared from Ca(BH4)2·2 THF by ligand displacement. IR and NMR data are in agreement with the presence of a nonionic BH4 group, but a specific binding to calcium could not be deduced unambiguously. However, the X-ray structure analysis of a single crystal of 1 reveals that the lattice is built up from molecules of 1 in which each BH4 group binds to Ca via three hydrogen atoms, and the ether forms a chelate. Therefore, calcium in 1 is decacoordinated. Taking the boron atoms as the center of gravity for the BH4 groups one can best describe the coordination as being derived from a strongly distorted octahedron due to repulsive interactions of the BH4 groups as well as of the "bite” of the chelating diether which im poses a O-Ca-O bond angle of ~ 67°.