Metal Borohydrides beyond Groups I and II: A Review

Suárez‐Alcántara, K.; García, Juan Rogelio Tena Tena

doi:10.3390/ma14102561

Cited by 23 publications

(43 citation statements)

References 272 publications

(850 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Metal tetrahydroborates are fascinating compounds with several real and potential applications, including organic synthesis, hydrogen storage, electroless plating, and the synthesis of nanomaterials. − One of the first such compounds discovered was U(BH 4 ) 4 , which was evaluated during World War II as the transporting agent in the separation of fissile 235 U from uranium ores by gas diffusion. , Interest in U(BH 4 ) 4 for this purpose stemmed from the fact that it was one of the few volatile uranium compounds known. Ultimately, U(BH 4 ) 4 was rejected in favor of UF 6 because the hexafluoride can withstand higher temperatures without decomposing (and thus can generate higher vapor pressures of uranium-bearing material).…”

Section: Introductionmentioning

confidence: 99%

X-ray Crystal Structure of Thorium Tetrahydroborate, Th(BH₄)₄, and Computational Studies of An(BH₄)₄ (An = Th, U)

et al. 2021

View full text Add to dashboard Cite

The crystal structure of Th(BH4)4 is described. Two of the four BH4 – ions are terminal and tridentate (κ3), whereas the other two bridge between neighboring ThIV centers in a κ2,κ2 (i.e., bis-bidentate) fashion. Thus, each thorium center is bound to six BH4 – groups by 14 Th–H bonds. The six boron atoms describe a distorted octahedron in which the κ3-BH4 – ions are mutually cis; the 14 ligating hydrogen atoms define a highly distorted bicapped hexagonal antiprism. The thorium centers are linked into a polymer consisting of interconnected helical chains wound about 4-fold screw axes. The structures of An(BH4)4 (An = Th, U) were also investigated by DFT. The geometries of [An(BH4)6]2–, [An3(BH4)16]4–, and [An5(BH4)26]6– fragments of the polymeric structures were optimized at the B3LYP and/or PBE levels. Most calculated geometries are 14-coordinate and agree with the experimental structures, but isolated [Th(BH4)6]2– units are predicted to feature 16-coordinate ThIV centers.

show abstract

Section: Introductionmentioning

confidence: 99%

X-ray Crystal Structure of Thorium Tetrahydroborate, Th(BH₄)₄, and Computational Studies of An(BH₄)₄ (An = Th, U)

et al. 2021

View full text Add to dashboard Cite

show abstract

“…The mechano-chemical synthesis route is perhaps the most-used and best-known method to obtain metal borohydrides; it is also the only one able to afford mixed-cation borohydrides (like LiZn 2 (BH 4 ) 5 ) [ 41 ]. The main drawback of ball-milling / the mechano-chemical route is the impurity of the resulting borohydride with metal halides, which are by-products of the metathesis reaction [ 42 , 43 , 44 , 45 , 46 ]. By contrast, wet-chemistry methods can yield phase-pure metal borohydrides, and they afford far easier separation procedures.…”

Section: General Synthesis Strategies For Metal Borohydrides M(bh ...mentioning

confidence: 99%

Complex Metal Borohydrides: From Laboratory Oddities to Prime Candidates in Energy Storage Applications

Comănescu

2022

Materials

View full text Add to dashboard Cite

Despite being the lightest element in the periodic table, hydrogen poses many risks regarding its production, storage, and transport, but it is also the one element promising pollution-free energy for the planet, energy reliability, and sustainability. Development of such novel materials conveying a hydrogen source face stringent scrutiny from both a scientific and a safety point of view: they are required to have a high hydrogen wt.% storage capacity, must store hydrogen in a safe manner (i.e., by chemically binding it), and should exhibit controlled, and preferably rapid, absorption–desorption kinetics. Even the most advanced composites today face the difficult task of overcoming the harsh re-hydrogenation conditions (elevated temperature, high hydrogen pressure). Traditionally, the most utilized materials have been RMH (reactive metal hydrides) and complex metal borohydrides M(BH4)x (M: main group or transition metal; x: valence of M), often along with metal amides or various additives serving as catalysts (Pd2+, Ti4+ etc.). Through destabilization (kinetic or thermodynamic), M(BH4)x can effectively lower their dehydrogenation enthalpy, providing for a faster reaction occurring at a lower temperature onset. The present review summarizes the recent scientific results on various metal borohydrides, aiming to present the current state-of-the-art on such hydrogen storage materials, while trying to analyze the pros and cons of each material regarding its thermodynamic and kinetic behavior in hydrogenation studies.

show abstract

“…The titanium(III) tetrahydridoborato complexes exhibit variable thermal stability depending on the presence of other accompanying ligands in the coordination sphere of the metal. For instance, the homoleptic tetrahydridoborato complex [Ti(BH 4 ) 3 ] is an unstable volatile material that decomposes spontaneously at room temperature with hydrogen and diborane release . The thermal stability is enhanced in Lewis acid–base adducts [Ti(BH 4 ) 3 L n ] ( n = 1, 2) or by replacement of BH 4 units by strong stabilizing cyclopentadienyl ligands.…”

Section: Introductionmentioning

confidence: 99%

Monocyclopentadienyltitanium(III) Complexes with Hydridoborato Ligands

et al. 2023

View full text Add to dashboard Cite

The synthesis, properties, and reactivity of monocyclopentadienyltitanium(III) complexes stabilized by hydridoborato (BH3R)− ligands are reported. The reactions of the titanium(IV) trichlorides [Ti(η5-C5H5–n Me n )Cl3] with excess LiBH3R (R = H, Me) afford dimeric [{Ti(η5-C5H5–n Me n )(BH4)(μ-BH4)}2] (n = 5 (1), 4 (2), 0 (3)) or monomeric [Ti(η5-C5Me5)(BH3Me)2] (4) titanium(III) derivatives. Compound 3 is a thermally unstable oil and decomposes at room temperature forming a mixed-valence TiII/TiIII tetrametallic species [{Ti(η5-C5H5)(BH4)}2{(μ3-B2H6)Ti(η5-C5H5)}2] (5) with dianionic diborane(6) ligands in a rare μ3-κ2:κ2:κ2-B2H6 coordination mode. Density functional theory (DFT) calculations for 5 agree with a triplet ground state with two inner titanium(II) atoms bonded by a single bond and two outer titanium(III) centers. In contrast to 3, the monomeric tetrahydrofuran adduct derivative [Ti(η5-C5H5)(BH4)2(thf)] (6) is a stable solid. Dimeric 1–3 react with 2,6-lutidinium salts (LutH)X (X = BPh4, OSO2CF3) to afford ion pairs, [Ti(η5-C5H5–n Me n )(BH4)L2](BPh4) (L = thf, n = 5 (7), 4 (8), 0 (9); L = py, n = 5 (10)), or molecular aggregates, [{Ti(η5-C5Me5)(BH4)(μ-O2SOCF3)}2] (11) and [{Ti(η5-C5H5–n Me n )(μ-O2SOCF3)2} x ] (n = 5, x = 3 (12); n = 4, x = 4 (13)), via formation of H2 and (Lut)BH3. Diamagnetic titanium(II) derivatives [{Ti(η5-C5Me5)(μ-H)}2{(μ-H)2Al(BH3R)(thf)}2] (R = H (14), Me (15)) were isolated in reactions of complexes 1 and 4 with LiAlH4 in tetrahydrofuran.

show abstract

Metal Borohydrides beyond Groups I and II: A Review

Cited by 23 publications

References 272 publications

X-ray Crystal Structure of Thorium Tetrahydroborate, Th(BH₄)₄, and Computational Studies of An(BH₄)₄ (An = Th, U)

X-ray Crystal Structure of Thorium Tetrahydroborate, Th(BH₄)₄, and Computational Studies of An(BH₄)₄ (An = Th, U)

Complex Metal Borohydrides: From Laboratory Oddities to Prime Candidates in Energy Storage Applications

Monocyclopentadienyltitanium(III) Complexes with Hydridoborato Ligands

Contact Info

Product

Resources

About

Metal Borohydrides beyond Groups I and II: A Review

Cited by 23 publications

References 272 publications

X-ray Crystal Structure of Thorium Tetrahydroborate, Th(BH4)4, and Computational Studies of An(BH4)4 (An = Th, U)

X-ray Crystal Structure of Thorium Tetrahydroborate, Th(BH4)4, and Computational Studies of An(BH4)4 (An = Th, U)

Complex Metal Borohydrides: From Laboratory Oddities to Prime Candidates in Energy Storage Applications

Monocyclopentadienyltitanium(III) Complexes with Hydridoborato Ligands

Contact Info

Product

Resources

About

X-ray Crystal Structure of Thorium Tetrahydroborate, Th(BH₄)₄, and Computational Studies of An(BH₄)₄ (An = Th, U)

X-ray Crystal Structure of Thorium Tetrahydroborate, Th(BH₄)₄, and Computational Studies of An(BH₄)₄ (An = Th, U)