- Triorganyl- and diorganyloxozirconium hydridoborates - Synthesis and structures
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The reactions of Zr(OBu)4 and Zr(OEt)4 with H 3B·THF in THF led to HB(OR)2 and B(OR)3, but no zirconium tetrahydroborate [(RO)4-nZr(BH4) n] could be isolated. On the contrary, the reactions of [tBu 3CO]4-nZrCln and [tBu3SiO] 4-nZrCln with LiBH4 generated the tetrahydroborates [(RO)3Zr(BH4)] and [(RO) 2Zr(BH4)2]. These can be used to produce by hydroborate exchange dihydridodiorganyl borates [(RO)4-nZr(H 2BC8H14)n] and byproducts. The structures of the new zirconium hydridoborates have been determined by X-ray crystallography. Compound [(tBu3CO)3Zr(H 2BC8H14)] shows site-disordered dihydroborate units with agostic Zr-H-C interactions, while [(tBu3SiO) 2Zr(H2BC8H14)2] is quite symmetric (C2/c). The corresponding tetrahydridoborates possess in most cases μ31-bonded ZrH3BH groups. Compounds of the type [(RO)4-nZr(BH4)n] were obtained from the reaction of(RO)4Zr (R = Bu, Et) with H 3B·THF or that of (RO)4-nZrCln(n = 1, 2; R = tBu3C, tBu3Si) with LiBH4. Boryl group exchange with H2BC8H14- leads to (RO)4Zr(H2BC8H14)n with agostic Zr-H-B bonding when n = 1, whereas a symmetric ZrH2B compound results when n = 2. Copyright
- Knizek, Joerg,Noeth, Heinrich,Schmidt-Amelunxen, Martin
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p. 5548 - 5557
(2012/02/04)
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- Metal Tetrahydridoborates and Tetrahydridoborato metalates, 18. Preparation and Molecular Structures of Tetrahydrofuran, Diethylene Diglycol Dimethyl Ether and 18-Crown-6 Complexes of Strontium and Barium Tetrahydridoborate
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The srontium 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. - Key Words: Strontium bis(tetrahydridoborate)-2 tetrahydrofuran, chain polymer of/ Strontium bis(tetrahydridoborate)-bis(diglyme) / Barium bis(tetrahydridoborate)-bis(diglyme) / Strontium bis(tetrahydridoborate)-1,4,7,13,16-hexaoxacyclooctadecane / Metal-hydrogen-boron briges
- Bremer, Mathias,Noeth, Heinrich,Thomann, Martina,Schmidt, Martin
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p. 455 - 460
(2007/10/02)
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