Tetrabutylammonium cation in a homoleptic environment of borohydride ligands: [(n-Bu)4N][BH4] and [(n-Bu)4N][Y(BH4)4]

Jaroń, Tomasz; Wegner, Wojciech; Cyrański, Michał K.; Dobrzycki, Łukasz; Grochala, Wojciech

doi:10.1016/j.jssc.2012.03.040

Cited by 24 publications

(24 citation statements)

References 29 publications

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“…[10] Step The approach based on the reactions shown in Equations (3)-(5)h as resulted in the entire series of "dead mass"free unsolvated alkali metal yttrium borohydrides M (3) [Y(BH 4 ) 4 ] (M = Li, Na, K, Rb, or Cs). [10] Step The approach based on the reactions shown in Equations (3)-(5)h as resulted in the entire series of "dead mass"free unsolvated alkali metal yttrium borohydrides M (3) [Y(BH 4 ) 4 ] (M = Li, Na, K, Rb, or Cs).…”

Section: Resultsmentioning

confidence: 99%

Facile Formation of Thermodynamically Unstable Novel Borohydride Materials by a Wet Chemistry Route

Jaroń

Wegner

Fijałkowski

et al. 2015

Chemistry A European J

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A novel wet synthetic method utilizing weakly coordinating anions that yields LiCl-free Zn-based materials for hydrogen storage has recently been reported. Here we show that this method may also be applied for the synthesis of the pure yttrium derivatives, M[Y(BH4)4] (M = K, Rb, Cs). Moreover, it can be extended to the preparation of previously unknown thermodynamically unstable derivatives, Li[Y(BH4)4] and Na[Y(BH4)4]. Importantly, these two H-rich phases cannot be accessed by standard dry (mechanochemical) or solid/gas synthetic methods due to the thermodynamic obstacles. Here we describe their crystal structures and selected important physicochemical properties.

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Section: Resultsmentioning

confidence: 99%

Facile Formation of Thermodynamically Unstable Novel Borohydride Materials by a Wet Chemistry Route

Jaroń

Wegner

Fijałkowski

et al. 2015

Chemistry A European J

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“…In both cases the organic precursors are easily extracted with a solvent such as CH 2 Cl 2 , CHCl 3 , or toluene, in which metal halides are not soluble 18. Inorganic mixed‐cation borohydrides are prepared in step C, which involves a metathesis reaction in CH 2 Cl 2 ,…”

Section: Methodsmentioning

confidence: 99%

“…Our preliminary results indicate that the method described here may easily be transferred to other combinations of metal (M 2 , M 3 ) and organic ([ Cat ]) cations, because soluble complex borohydrides, [ Cat ] y [M 2 (BH 4 ) z ], have been reported for selected metals M 2 , for example, [Ph 4 P][Zn(BH 4 ) 3 ], [Ph 4 P] 2 [Mg(BH 4 ) 4 ], [Et 4 N][Al(BH 4 ) 4 ] 23. These compounds can be conveniently synthesized either in solvent‐mediated reactions, or in a one‐pot mechanochemical process followed by the extraction as for [ Cat ][Y(BH 4 ) 4 ] 18. These organic mixed‐cation borohydrides are typically more thermally stable than the parent metal borohydrides,1b which further facilitates their use for the synthesis of M 3 y [M 2 (BH 4 ) z ] 11.…”

Section: Methodsmentioning

confidence: 99%

Hydrogen Storage Materials: Room‐Temperature Wet‐Chemistry Approach toward Mixed‐Metal Borohydrides

et al. 2014

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The poor kinetics of hydrogen evolution and the irreversibility of the hydrogen discharge hamper the use of transition metal borohydrides as hydrogen storage materials, and the drawbacks of current synthetic methods obstruct the exploration of these systems. A wet-chemistry approach, which is based on solvent-mediated metathesis reactions of precursors containing bulky organic cations and weakly coordinating anions, leads to mixed-metal borohydrides that contain only a small amount of "dead mass". The applicability of this method is exemplified by Li[Zn 2 (BH 4 ) 5 ] and M[Zn(BH 4 ) 3 ] salts (M = Na, K), and its extension to other systems is discussed.The efficient storage of hydrogen is one of the most pressing problems related to utilization of the lightest element as an energy carrier. [1] Metal borohydrides contain large amounts of hydrogen compared to other groups of inorganic compounds (up to 24.5 wt % for NH 4 BH 4 ) [2] and have been intensely examined as potential materials for hydrogen storage. [3] The properties of metal borohydrides that limit their applicability as hydrogen storage materials (such as temperature of H 2 release [4] and reversibility) can be tuned-up to some extent by the substitution at the metal or ligand site or by the preparation of complex materials, [5] e.g. LiK(BH 4 ) 2 , [4] M[Sc-(BH 4 ) 4 ], M = Li, Na, K, [6] Li 3 MZn 5 (BH 4 ) 15 , M = Mg, Mn. [7] The most frequently used synthetic pathway toward unsolvated single-and mixed-metal borohydrides consists of a mechanochemical reaction between a metal halide and an alkali metal borohydride. [3] For example:The method can be easily extended to mixtures of the three substrates.The mechanochemical (high-energy milling) method, although very convenient for the initial screening of a wide variety of single-and mixed-metal borohydrides, [10] has serious drawbacks, which hamper the application of this method on an industrial scale. One key disadvantage is the presence of halide-containing by-products in the sample [Equations (1) [8] and (2) [9] ]. This "dead mass" usually constitutes 40-60 wt % of the composite, which dramatically decreases the effective hydrogen content and often influences the thermal decomposition process, for example, through the formation of halide-substituted borohydrides. [6c, 11] For example, the total hydrogen content of Li[Zn 2 (BH 4 ) 5 ] decreases from 9.5 wt % to less than 5.3 wt % (i.e. below the 2017 US Department of Energy limit of 5.5 wt %) for the composite product obtained according to Equation (2). The separation methods based on the difference of buoyancy of the products or solubility of borohydrides in ethereal solvents either do not work or lead to ether-solvated products. [12] Most ethers contribute even more to the dead mass than alkali metal halides, they compromise the purity of the evolved H 2 gas, and they often cannot be removed without thermal decomposition of the borohydrides, especially those which evolve H 2 in the desirable low-temperature range (60-100 8C). [13] On the other hand, ...

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“…Numerous related borohydrides of other metals with tridentate BH 4 groups have been prepared in the past, e.g. Zr(BH 4 ) 4 , Hf(BH 4 ) 4 , MSc(BH 4 ) 4 (M = Li, Na, K; Broach et al, 1983;Hagemann et al, 2008;Č erný, Ravnsbaek et al, 2010;Č erný, Severa et al, 2010) and MY(BH 4 ) 4 [M = K, Rb, Cs, (CH 3 ) 4 N or (n-C 4 H 9 ) 4 N; Jaroń & Grochala, 2011;Jaroń et al, 2012Jaroń et al, , 2013. The M + cations in (I) and (II) are coordinated by six BH 4 groups, forming a compressed octahedron.…”

Section: Figurementioning

confidence: 99%

MYb(BH₄)₄(M= K, Na) from laboratory X-ray powder data

Wegner¹,

Jaroń²,

Grochala³

2013

Acta Crystallogr C

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Two new borohydrides, potassium ytterbium tetraborohydride, KYb(BH4)4, and sodium ytterbium tetraborohydride, NaYb(BH4)4, have been synthesized via mechanochemical reactions in the solid state. The two compounds are isostructural and both crystallize in the Cmcm space group in the structure reported previously for NaSc(BH4)4 and KY(BH4)4. This crystal structure is composed of isolated homoleptic [Yb(BH4)4](-) anions surrounded by M(+) cations (M = Na, K). The packing of the M(+) cations and [Yb(BH4)4](-) anions is a distorted variant of the hexagonal NiAs structure type, with M(+) forming distorted trigonal prisms, i.e. M6. Each second prism surrounds a [Yb(BH4)4](-) anion, while the [Yb(BH4)4](-) anions are arranged into deformed octahedra around the M(+) cations.

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Tetrabutylammonium cation in a homoleptic environment of borohydride ligands: [(n-Bu)4N][BH4] and [(n-Bu)4N][Y(BH4)4]

Cited by 24 publications

References 29 publications

Facile Formation of Thermodynamically Unstable Novel Borohydride Materials by a Wet Chemistry Route

Facile Formation of Thermodynamically Unstable Novel Borohydride Materials by a Wet Chemistry Route

Hydrogen Storage Materials: Room‐Temperature Wet‐Chemistry Approach toward Mixed‐Metal Borohydrides

MYb(BH₄)₄(M= K, Na) from laboratory X-ray powder data

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Tetrabutylammonium cation in a homoleptic environment of borohydride ligands: [(n-Bu)4N][BH4] and [(n-Bu)4N][Y(BH4)4]

Cited by 24 publications

References 29 publications

Facile Formation of Thermodynamically Unstable Novel Borohydride Materials by a Wet Chemistry Route

Facile Formation of Thermodynamically Unstable Novel Borohydride Materials by a Wet Chemistry Route

Hydrogen Storage Materials: Room‐Temperature Wet‐Chemistry Approach toward Mixed‐Metal Borohydrides

MYb(BH4)4(M= K, Na) from laboratory X-ray powder data

Contact Info

Product

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MYb(BH₄)₄(M= K, Na) from laboratory X-ray powder data