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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Na(BH)5 by Materials Project

Na2(BH)9BH crystallizes in the monoclinic P2_1/c space group. The structure is one-dimensional and consists of four boranediylradical molecules and two Na2(BH)9 ribbons oriented in the (1, 0, 0) direction. In each Na2(BH)9 ribbon, there are two inequivalent Na sites. In the first Na site, Na is bonded in a 3-coordinate geometry to six H atoms. There are a spread of Na–H bond distances ranging from 2.09–2.61 Å. In the second Na site, Na is bonded in a 7-coordinate geometry to seven H atoms. There are a spread of Na–H bond distances ranging from 2.40–2.70 Å. There are nine inequivalent B sites. In the first B site, B is bonded in a distorted single-bond geometry to one H atom. The B–H bond length is 1.20 Å. In the second B site, B is bonded in a distorted single-bond geometry to one H atom. The B–H bond length is 1.20 Å. In the third B site, B is bonded in a distorted single-bond geometry to one H atom. The B–H bond length is 1.21 Å. In the fourth B site, B is bonded in a distorted single-bond geometry to one H atom. The B–H bond length is 1.20 Å. In the fifth B site, B is bonded in a distorted single-bond geometry to one H atom. The B–H bond length is 1.19 Å. In the sixth B site, B is bonded in a distorted single-bond geometry to one H atom. The B–H bond length is 1.21 Å. In the seventh B site, B is bonded in a distorted single-bond geometry to one H atom. The B–H bond length is 1.21 Å. In the eighth B site, B is bonded in a distorted single-bond geometry to one H atom. The B–H bond length is 1.21 Å. In the ninth B site, B is bonded in a distorted single-bond geometry to one H atom. The B–H bond length is 1.20 Å. There are nine inequivalent H sites. In the first H site, H is bonded in a 3-coordinate geometry to two Na and one B atom. In the second H site, H is bonded in a distorted single-bond geometry to two equivalent Na and one B atom. In the third H site, H is bonded in a 2-coordinate geometry to two Na and one B atom. In the fourth H site, H is bonded in a linear geometry to one Na and one B atom. In the fifth H site, H is bonded in a linear geometry to one Na and one B atom. In the sixth H site, H is bonded in a distorted water-like geometry to one Na and one B atom. In the seventh H site, H is bonded in a distorted single-bond geometry to two Na and one B atom. In the eighth H site, H is bonded in a single-bond geometry to one Na and one B atom. In the ninth H site, H is bonded in a distorted single-bond geometry to one Na and one B atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na(BH)6 by Materials Project

Na(BH)5BH crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four boranediylradical molecules and two Na(BH)5 clusters. In each Na(BH)5 cluster, Na is bonded in a 6-coordinate geometry to six H atoms. There are a spread of Na–H bond distances ranging from 2.28–2.54 Å. There are five inequivalent B sites. In the first B site, B is bonded in a single-bond geometry to one H atom. The B–H bond length is 1.21 Å. In the second B site, B is bonded in a single-bond geometry to one H atom. The B–H bond length is 1.21 Å. In the third B site, B is bonded in a single-bond geometry to one H atom. The B–H bond length is 1.20 Å. In the fourth B site, B is bonded in a single-bond geometry to one H atom. The B–H bond length is 1.20 Å. In the fifth B site, B is bonded in a single-bond geometry to one H atom. The B–H bond length is 1.21 Å. There are five inequivalent H sites. In the first H site, H is bonded in a water-like geometry to one Na and one B atom. In the second H site, H is bonded in a water-like geometry to one Na and one B atom. In the third H site, H is bonded in a distorted water-like geometry to one Na and one B atom. In the fourth H site, H is bonded in a distorted single-bond geometry to two equivalent Na and one B atom. In the fifth H site, H is bonded in a water-like geometry to one Na and one B atom.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Mechanochemical synthesis and structural analysis of trivalent lanthanide and uranium diphenylphosphinodiboranates

Phosphinodiboranates (H 3 BPR 2 BH 3 – ) are a class of borohydrides that have merited a reputation as weakly coordinating anions, which is attributed in part to the dearth of coordination complexes known with transition metals, lanthanides, and actinides. We recently reported how K(H 3 BP t Bu 2 BH 3 ) exhibits sluggish salt elimination reactivity with f-metal halides in organic solvents such as Et 2 O and THF. Here we report how this reactivity appears to be further attenuated in solution when the t Bu groups attached to phosphorus are exchanged for R = Ph or H, and we describe how mechanochemistry was used to overcome limited solution reactivity with K(H 3 BPPh 2 BH 3 ). Grinding three equivalents of K(H 3 BPPh 2 BH 3 ) with UI 3 (THF) 4 or LnI 3 (Ln = Ce, Pr, Nd) allowed homoleptic complexes with the empirical formulas U(H 3 BPPh 2 BH 3 ) 3 (1), Ce(H 3 BPPh 2 BH 3 ) 3 (2), Pr(H 3 BPPh 2 BH 3 ) 3 (3), and Nd(H 3 BPPh 2 BH 3 ) 3 (4) to be prepared and subsequently crystallized in good yields (50–80%). Single-crystal XRD studies revealed that all four complexes exist as dimers or coordination polymers in the solid-state, whereas 1 H and 11 B NMR spectra showed that they exist as a mixture of monomers and dimers in solution. Treating 4 with THF breaks up the dimer to yield the monomeric complex Nd(H 3 BPPh 2 BH 3 ) 3 (THF) 3 (4-THF). XRD studies revealed that 4-THF has one chelating and two dangling H 3 BPPh 2 BH 3 – ligands bound to the metal to accommodate binding of THF. In contrast to the results with K(H 3 BPPh 2 BH 3 ), attempting the same mechanochemical reactions with Na(H 3 BPH 2 BH 3 ) containing the simplest phosphinodiboranate were unsuccessful; only the partial metathesis product U(H 3 BPH 2 BH 3 )I 2 (THF) 3 (5) was isolated in poor yields. Here, despite these limitations, our results offer new examples showing how mechanochemistry can be used to rapidly synthesize molecular coordination complexes that are otherwise difficult to prepare using more traditional solution methods.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Synthesis of Cp* Terphenylamido U(III) Iodide Complexes with a Substitutable Iodide Position to Generate Terminal U(III)–(κ 3 -BH 4 ) Complexes

Reaction of Cp*UI 2 (THF) 3 (Cp* = pentamethylcyclopentadienide; THF = tetrahydrofuran) with Na R3 TerNH ( R3 Ter = 2,6(2,4,6-R 3 C 6 H 2 ) 2 C 6 H 3 ; R = Me, Et, iPr) gave the U(III) monoiodide complexes Cp*( R3 TerNH)UI (R = Me, 1-Me; R = Et, 2-Et; R = iPr, 3-iPr). These complexes contain a functionalizable iodide position which reacts favorably with NaBH4 to give the κ 3 -borohydride complexes Cp*( R3 TerNH)U(H 3 BH) (R = Me, 4-Me; R = Et, 5-Et; R = iPr, 6-iPr). All compounds were experimentally characterized by SC-XRD, 1 H and 11 B NMR spectroscopy as well as UV–vis–NIR and FTIR analyses. DFT calculations corroborate the experimental findings, confirming the 5f 3 U(III) configuration across the entire series and revealing an increased U 5f orbital contribution in the borohydride derivatives. All compounds exhibit small but non-negligible U(III)–(η 6 -arene) δ-back-bonding interactions arising from the unpaired 5f electrons. Calculated steric parameters show progressively greater shielding of the U(III) center with increasing bulk of the terphenyl substituents from Me to iPr.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗