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The Structure of Some Amine Solvates of Magnesium Bis(tetrahydroborate) and DFT Calculations on Solvates of Lithium Tetrahydroborate
Author(s) -
Bremer Mathias,
Nöth Heinrich,
Warchhold Marcus
Publication year - 2003
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200390011
Subject(s) - chemistry , molecule , alkali metal , crystallography , magnesium , crystal structure , hydrogen bond , ionic bonding , inorganic chemistry , ammonia , lithium (medication) , trigonal bipyramidal molecular geometry , amine gas treating , lattice energy , ion , organic chemistry , medicine , endocrinology
Eight solvates of magnesium bis(tetrahydroborate) have been prepared and characterised by NMR and IR spectroscopy, and five of them also by X‐ray crystallography. Compounds Mg(BH 4 ) 2 ·3NH 2 t Bu and Mg(BH 4 ) 2 ·3pip each have a distorted trigonal‐bipyramidal structure (with the BH 4 group viewed as a simple ligand) while the putative Mg(BH 4 ) 2 ·6py proved to be [Mg(BH 4 ) 2 ·4py] with a pseudooctahedral structure, two py molecules being present as solvent of crystallization. Similarly, Mg(BH 4 ) 2 ·8DMSO contains the cation [Mg(DMSO) 6 ] 2+ in the crystal, and Mg(BH 4 ) 2 ·6NH 2 Bzl has an ionic lattice made up of Mg(NH 2 Bzl) 6 2+ and BH 4 − ions. The BH 4 groups in the molecular compounds are bonded to the Mg centre through double hydrogen bonds. In order to study the bonding in alkali and alkali earth metal tetrahydroborates, DFT calculations were performed for LiBH 4 and its ammonia and dimethyl ether solvates. The minimum‐energy structure for a LiBH 4 molecule has C 3v symmetry; this is not changed when one ammonia molecule is added and is also the result for LiBH 4 ·3NH 3 . Addition of the first NH 3 or Me 2 O molecule contributes more to the stabilisation than a second or a third molecule. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)