862776-00-9Relevant articles and documents
Metal tetrahydroborates and tetrahydroborato metalates. 30 [1] Solvates of alcoholato-, phenolato-, and bis(trimethylsilyl)amido-magnesium tetrahydroborates XMgBH4(Ln)
Bremer, Mathias,Linti, Gerald,Noeth, Heinrich,Thomann-Albach, Martina,Wagner, Gerhardt E. W. J.
, p. 683 - 697 (2008/10/09)
A series of alcoholato and phenolato magnesium tetrahydroborates have been prepared as solvates (RO)Mg(BH4)(OEt2) by 1:1 reactions of ROH (R = Me, Et, iPr, tBu, CH2CMe3, Et2(tBu)C, Ph3C, Ph, 2,4,6-Me3C6H2, (2,6-iPr)2C6H3, (2,6-tBu2)C 6H3, 2-(iPrO)C6H4, 2,6-(MeO) 2C6H3) with diethyl ether solutions of EtMg(BH4). Displacement of diethyl ether by thf, dme, and diglyme produced various solvates (RO)Mg(BH4)(L)n (L = thf, dme, diglyme, n = 1, 2, 3). Most of these compounds are centrosymmetric dimers with a central Mg2O2 four membered ring. Irrespective of the composition, the 11B NMR signals are 1:4:6:4:1 quintets showing that the hydrogen atoms of the BH4 groups are magnetically equivalent. The molecular structure of eight compounds [(RO)Mg(BH4)(OEt 2)]2 (R = iPr, tBu, tBuCH2, Et3C, Me3Si), [(PhO)Mg(BH4)(thf)2]2, (2,6-tBu2C6H3O)Mg(BH4)(thf) 2, (2,6-tBu2- C6H3O)-Mg(BH 4)(thf)(dme)) have been determined. Typical for all compounds are hexacoordinated Mg atoms. The mononuclear complexes feature bidentate BH 4 groups while dinuclear species show di- or tridentate BH 4 groups depending on the number of coordinated O atoms. Mononuclear species are obtained only for compounds with bulky R groups, e. g. 2,6-(tBu 2)(C6H3O)Mg(BH4)(thf)2 with tridentate BH4 groups. This compound has a linear O-C-Mg unit. In Me2SO the compound [(2-iPrO)C6H4O]Mg(BH 4)(OEt2) underwent ligand exchange to produce [(2-iPrO)C6H4O]2Mg(OSMe2)] 2. Reaction of EtMgBH4 with a stoichiometric amount (1:1) of (Me3-Si)2NH gives [((Me3Si) 2N)-Mg(BH4)(OEt2)]2, 46 with a tridentate BH4 group. Its diethyl ether molecule can be replaced by thf, dme and diglyme. Amongst these solvates the compound [(Me 3-Si)2N]Mg(BH4)(diglyme) is mononuclear and its structure shows a bidentate BH4 group. Compound 46 on repeated crystallization from diethyl ether is transformed into [(Me3SiO) Mg(BH4)(OEt2)]2. No compound with a BH 4 group bonded to two Mg atoms has so far been found.
