Volatile metal borohydride complexes: synthesis and characterization of new chemical vapor deposition precursors
type: CreativeWork
description: The complex sodium methylborohydride, Na(H3BCH3), can be prepared in high yield (83%) by the addition of trimethylboroxine, (H3C)3B3O3, to sodium aluminum hydride, NaAlH4. The subsequent reaction of two equivalents of sodium methylborohydride with the alkaline earth bromides; MgBr2, CaBr2, SrBr2, and BaBr2 in 1,2-dimethoxyethane, DME, affords the new alkaline earth methylborohydride DME adducts: [Mg(H3BCH3)2(DME)]2, Ca(H3BCH3)2(DME)2, Sr(H3BCH3)2(DME)3, and Ba(H3BCH3)2(DME)3. [Mg(H3BCH3)2(DME)]2 sublimes between 80 and 90 °C at 10 mTorr while the larger alkaline earth methylborohydrides do not sublime up to 120 °C. [Mg(H3BCH3)2(DME)]2 is an asymmetrically bridged dimer in the solid state where each Mg center has a terminal κ2H-methylborohydride, a bridging κ2H-methylborohydride, a bridging κ1H-methylborohydride, and a chelating DME. The other alkaline earth methyborohydrides have two κ3H-methylborohydrides and two chelating DME for the Ca complex and three chelating DME for the Sr and Ba complexes. Rare earth methylborohydride THF adducts are prepared by the reaction of a rare earth chloride (Sc, Y, Nd, Gd, Er) with 3 to 4 equivalents of sodium methylborohydride in THF. The scandium and yttrium complexes are isolated by sublimation at 50 °C while the neodymium, gadolinium, and erbium complexes are isolated by sublimation at 60 °C. In the solid state, scandium methylborohydride has three κ3H-methylborohydrides and one coordinated THF. The yttrium, gadolinium, and erbium complexes crystallize as charge separated ion pairs: [RE(H3BCH3)2(THF)4] [RE(H3BCH3)4], where the cation has two κ3H-methylborohydrides and four coordinated THF and the anion consists of four κ3H-methylborohydrides. The neodymium complex is a methylborohydride bridged dimer, [Nd(H3BCH3)3(THF)2]2, where each Nd center has two κ3H-methylborohydrides, two bridging κ2H,κ2H-methylborohydrides and two THF. In addition to the THF adducts, the neodymium DME adduct, Nd(H3BCH3)3(DME)1.5, has also been synthesiz…
abstract: The complex sodium methylborohydride, Na(H3BCH3), can be prepared in high yield (83%) by the addition of trimethylboroxine, (H3C)3B3O3, to sodium aluminum hydride, NaAlH4. The subsequent reaction of two equivalents of sodium methylborohydride with the alkaline earth bromides; MgBr2, CaBr2, SrBr2, and BaBr2 in 1,2-dimethoxyethane, DME, affords the new alkaline earth methylborohydride DME adducts: [Mg(H3BCH3)2(DME)]2, Ca(H3BCH3)2(DME)2, Sr(H3BCH3)2(DME)3, and Ba(H3BCH3)2(DME)3. [Mg(H3BCH3)2(DME)]2 sublimes between 80 and 90 °C at 10 mTorr while the larger alkaline earth methylborohydrides do not sublime up to 120 °C. [Mg(H3BCH3)2(DME)]2 is an asymmetrically bridged dimer in the solid state where each Mg center has a terminal κ2H-methylborohydride, a bridging κ2H-methylborohydride, a bridging κ1H-methylborohydride, and a chelating DME. The other alkaline earth methyborohydrides have two κ3H-methylborohydrides and two chelating DME for the Ca complex and three chelating DME for the Sr and Ba complexes. Rare earth methylborohydride THF adducts are prepared by the reaction of a rare earth chloride (Sc, Y, Nd, Gd, Er) with 3 to 4 equivalents of sodium methylborohydride in THF. The scandium and yttrium complexes are isolated by sublimation at 50 °C while the neodymium, gadolinium, and erbium complexes are isolated by sublimation at 60 °C. In the solid state, scandium methylborohydride has three κ3H-methylborohydrides and one coordinated THF. The yttrium, gadolinium, and erbium complexes crystallize as charge separated ion pairs: [RE(H3BCH3)2(THF)4] [RE(H3BCH3)4], where the cation has two κ3H-methylborohydrides and four coordinated THF and the anion consists of four κ3H-methylborohydrides. The neodymium complex is a methylborohydride bridged dimer, [Nd(H3BCH3)3(THF)2]2, where each Nd center has two κ3H-methylborohydrides, two bridging κ2H,κ2H-methylborohydrides and two THF. In addition to the THF adducts, the neodymium DME adduct, Nd(H3BCH3)3(DME)1.5, has also been synthesiz…
author: Mallek, Justin
language: en
keywords: inorganic synthesis, chemical vapor deposition, precursor, thin films, rare earth metal, lanthanide, borohydride
date published: 2014-09-16T17:17:39Z
date modified: 2026-07-22T22:25:40Z
provider: University of Illinois - Urbana-Champaign
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Illinois at Urbana-Champaign

PropertyValue
property ID: Handle
value: http://hdl.handle.net/2142/50455