A facile solvent-free method for NaBH4 and Na2B12H12 synthesis

Article abstract of DOI:10.1016/j.ica.2018.01.010

Sodium tetrahydroborate (NaBH₄) and dodecahydro-closo-dodecaborate (Na₂B₁₂H₁₂) are both important inorganic compounds presenting multiple applications. Nevertheless, multistep and complicated conditions are usually demanded for their synthesis. In order to simplify the synthesis processes, we design a novel and facile solvent-free method for synthesizing NaBH₄ or Na₂B₁₂H₁₂ from NaNH₂ and B₁₀H₁₄. The product of either NaBH₄ or Na₂B₁₂H₁₂ is manipulable by simply adjusting the ratio of NaNH₂ to B₁₀H₁₄. The reaction equations of synthesizing NaBH₄ and Na₂B₁₂H₁₂ are proposed and verified, and the reaction pathways are elucidated. The findings here supply new insight to synthesize metal dodecaborates using the strategy of equal electron body for the first time and may shed light on synthesis of small metal B-H compounds from large B-H clusters.

Full text of DOI:10.1016/j.ica.2018.01.010

Inorganica Chimica Acta 474 (2018) 16–21
Contents lists available at ScienceDirect
Inorganica Chimica Acta
journal homepage: www.elsevier.com/locate/ica
Research paper
A facile solvent-free method for NaBH4 and Na2B12H12 synthesis
Liqing He a, Yanda Fu a,1, Dong Wu a,1, Dehui Zhang a, Hua Cheng a, Huaijun Lin b, Xiangnan Li a,
d,
e
Wei Xiong a, Qing Zhu a, Yonghong Deng a, Huaiyu Shao c, , Hai-Wen Li , Xingzhong Zhao ,
⇑
⇑
Zhouguang Lu a,
⇑
a Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
b Institute of Advanced Wear & Corrosion Resistance and Functional Materials, Jinan University, Guangzhou 510632, China
c Institute of Applied Physics and Materials Engineering (IAPME), University of Macau, Macau, China
d Kyushu University Platform of Inter/Transdisciplinary Energy Research (Q-PIT), Kyushu University, Fukuoka 819-0395, Japan
e Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education of China, Department of Electronic Science and Technology, School of Physics and Technology,
Wuhan University, Wuhan 430072, China
a r t i c l e i n f o
a b s t r a c t
Article history:
Sodium tetrahydroborate (NaBH4) and dodecahydro-closo-dodecaborate (Na2B12H12) are both important
inorganic compounds presenting multiple applications. Nevertheless, multistep and complicated condi-
tions are usually demanded for their synthesis. In order to simplify the synthesis processes, we design a
novel and facile solvent-free method for synthesizing NaBH4 or Na2B12H12 from NaNH2 and B10H14. The
Received 3 December 2017
Received in revised form 9 January 2018
Accepted 9 January 2018
product of either NaBH4 or Na2B12H12 is manipulable by simply adjusting the ratio of NaNH2 to B10H14
.
The reaction equations of synthesizing NaBH4 and Na2B12H12 are proposed and verified, and the reaction
pathways are elucidated. The findings here supply new insight to synthesize metal dodecaborates using
the strategy of equal electron body for the first time and may shed light on synthesis of small metal B-H
compounds from large B-H clusters.
Keywords:
Synthesis
NaBH4
Na2B12H12
Equal electron body
Reaction equation
Ó 2018 Elsevier B.V. All rights reserved.
1. Introduction
became increasingly important. Notably, Na2B12H12 was recently
reported to be suitable Na-ion conductors because it exhibits supe-
Both NaBH4 and Na2B12H12 are very influential inorganic mate-
rials which present broad applications in many fields. Metal boro-
hydride (M(BH4)n) is a kind of essential inorganic compound which
exhibits extensive application for chemical reactions [1,2], hydro-
gen storage [3,4] and solid-state ion batteries [5–7] etc. and there-
fore has been attracting tremendous research interests. Among
varieties of the M(BH4)n compounds, NaBH4, firstly discovered by
H. I. Schlesinger et al. in 1942 [8], is one of the most popular and
important B-H compounds. Thousands of tons of NaBH4 is pro-
duced and consumed annually, far exceeding the levels of any
other borohydride agents [9]. NaBH4 is considered as a promising
hydrogen storage material for its high hydrogen density (10.7
mass%, 114.5 kg/m3) [3]. During the de-/re-hydrogenation cycles
of NaBH4, formation of reaction intermediate- Na2B12H12 with
stable B12 skeleton is experimentally verified [10]. From then on,
Na2B12H12 began to attract more and more attentions and it
rior Na+ conductivity above its order-disorder phase transition
[11], many Na2B12H12-based superionic conductors with outstand-
ing Na+ conductivity were subsequently developed [12–15].
Besides the roles as reaction intermediate of NaBH4 and superionic
conductor, Na2B12H12 also shows important applications in drugs
such as boron neutron capture therapy for cancer treatment [4].
NaBH4 is usually produced by heating trimethyl borate with an
extremely fine dispersion of sodium hydride in boiling hydrocar-
bon oil at 250–280 °C, as shown in Eq. (1) [16]:
BðOCH3Þ3 þ 4NaH ! NaBH4 þ 3NaOCH3
ð1Þ
It can be also prepared by the reaction between metal Na and
borosilicate glass, as shown in Eq. (2): [17]
Na2B4O7 ꢀ 7SiO2 þ 16Na þ 8H2 ! 4NaBH4 þ 7Na2SiO3
ð2Þ
In these reactions, besides NaH or metal Na with high activity
and explosiveness, water & methanol or liquid ammonia are
needed for multistep separation and purification of NaBH4 under
rigorous reaction conditions.
⇑
Corresponding authors.
E-mail addresses: hshao@umac.mo (H. Shao), li.haiwen.305@m.kyushu-u.ac.jp
Na2B12H12 is usually synthesized via solution methods in which
triethylamineborane (Et3NBH3) and NaOH are used [18]. Anhydrous
(H.-W. Li), luzg@sustc.edu.cn (Z. Lu).
1
Equally contributing first author.
https://doi.org/10.1016/j.ica.2018.01.010
0020-1693/Ó 2018 Elsevier B.V. All rights reserved.

L. He et al. / Inorganica Chimica Acta 474 (2018) 16–21
17
Na2B12H12 is eventually obtained after a series of complicated
purification and careful dehydration processes from its hydrate
compounds. Solvent-free method is then in high importance to be
explored for Na2B12H12 preparation. Recently, we developed a facile
and simple solvent-free method for M2/nB12H12 synthesis by sinter-
ing M(BH4)n with B10H14 in sealed stainless-steel vessels, Na2B12H12
with high yield was successfully produced [19]. The reaction is
depicted as:
order to avoid air exposure during the measurement, all the sam-
ple powders were firstly placed in a quartz glass plate and then
sealed by Scotch tape in glove box filled with purified Ar. Raman
spectra were recorded by Horiba LabRAM HR Evolution using a
green laser with a wavelength of 532 nm. The 100–4000 cmꢂ1
wavenumber range was chosen in order to present all the B-H
vibrations.
The laboratory XPS data were obtained from Thermo SCIENTIFI-
C ESCALAB 250Xi with a micro-focused, monochromatic Al K
a
2NaBH4 þ B10H14 ! Na2B12H12 þ 5H2
ð3Þ
X-ray source at 1486.6 eV. All XPS spectra of samples were
recorded at room temperature without pretreatment. The XPS data
were collected from powders adhered to double-sided tape for the
basic measurements with spot diameter of 500 mm. The tube volt-
age and current were set as 15 kV and 10 mA, respectively.
Vacuum degree of analytical chamber was less than 2 ꢃ 10ꢂ9 mbar.
The gas products in sealed crucible were collected using tank
gas gathering method for GC-TCD analysis. The gas sample was
run on a gas chromatograph (Shiweipx GC-7806) equipped with
thermal conductivity detector (Molecular sieve 5A column) using
an Ar flow rate as 30 ml/min. The column was held at 120 °C and
the gaseous product was compared with the authentic gas
standards.
Considering the multistep and complicated conditions of liquid
phase methods for NaBH4 and Na2B12H12 synthesis and inspired by
Eq. (3), herein for the first time we proposed and experimentally
verified a novel and simple solvent-free method for both NaBH4
and Na2B12H12 synthesis using the strategy of equal electronic
body. NaNH2 with equal electron number to NaBH4 is used as Na
source for the possible similar property of NaNH2 to that of NaBH4
and the more abundant and convenient N than B source in earth.
B10H14 with large B10-skeleton is adopted as B source in order to
investigate the possibility of producing smaller borate of NaBH4
from larger B-H cluster compounds with higher stability [20]. Usu-
ally, B-H clusters are more stable with the enlarging of B-B skele-
ton and larger B-H cluster compounds are synthesized from the
smaller ones; however, smaller B-H cluster compounds synthe-
sized from the larger ones are hardly reported [4,19]. In this sim-
ple, interesting and efficient reaction, the product of either
NaBH4 or Na2B12H12 can be easily manipulated to synthesize by
Solid-state magic angle spinning nuclear magnetic resonance
(MAS NMR) spectra of 11B nuclei were measured using a Bruker
Advance 500 MHz spectrometer with an 11.7 T magnet and apply-
ing a Bruker 4 mm MAS probe. The spectral frequency was 160.50
for 11B nuclei. Single pulse (0.5 /12) 11B NMR experiments
ls-p
under MAS condition, with a typical spinning rate of 8 kHz, were
performed with strong 1H decoupling, and 11B cross-polarization
(CP) MAS spectra were also obtained occasionally as needed.
NMR shifts are reported in ppm when externally referenced to BF3-
ꢀEt2O (d = 0.00 ppm) for 11B NMR. The powder samples were loaded
into a 4 mm ZrO2 rotor and sealed with airtight Kel-F cap inside a
glove-box protected by purified Ar. Sample spinning was per-
formed under dry nitrogen gas.
simply adjusting the starting material ratio of NaNH2 to B10H14
.
2. Experimental
Commercial NaNH2 (99%, ThermoFisher Scientific) and B10H14
(98%, 3B Scientific) were all stored in glove box and used without
further purification. Stoichiometric ratio of starting materials
NaNH2 and B10H14 were firstly hand milled using agate mortar
and pestle for 0.5 h at room temperature under 0.1 MPa argon
in order to achieve a homogeneous mixture. Subsequently, the
hand milled products were sealed into (ꢁ0.7 cm3) stainless steel
crucibles for heat treatment under different conditions. The heat
treated products were retrieved for measurements and all the
operation was finished in glove box with pure Ar protection.
The X-ray diffraction patterns were recorded using Rigaku
The separation (peak deconvolution) of 11B MAS NMR curves
was done using the PeakFit 4.12 software with a Gaussian response
function, the goodness (r2) of the fit is higher than 0.97.
3. Results and discussion
The starting material 2NaNH2 + B10H14 is firstly hand milled
(HM) for 0.5 h, and then heat treated (HT) at 300 °C for 10 h
(marked as: 2:1-HM-0.5, 2:1-HT-300-10, similarly hereinafter).
Smartlab X-ray diffractometer with Cu-K
a radiation (k = 1.5418
Å) using 45 kV/200 mA as accelerating voltage/ tube current. In
(a)
BN
(b)
300 ºC 10 h
5:1 HT
300 ºC 10 h
5:1 HT
3.5:1 HT
2:1 HT
3.5:1 HT
2:1 HT
1:1 HT
1:1 HT
0.5:1 HT
0.5:1 HT
Na2B12H12
NaBH4
Na2B12H12
NaBH4
1000
2000
3000
4000
Raman shift (cm-1)
10 15 20 25 30 35 40 45 50 55 60
2theta (degree)
Fig. 1. XRD patterns (a) and Raman spectra (b) of the mixtures of xNaNH2 + B10H14 (0.5:1 ꢄ x:1 ꢄ 5:1) after 0.5 h of hand milling followed by heat treatment (HT) at 300 °C for
10 h.

18
L. He et al. / Inorganica Chimica Acta 474 (2018) 16–21
BN may exist in amorphous phase [22]. With the decreasing of
5NaNH2+B10H14
300 ºC 10 h
NaNH2 content, the produced BN decreases and it becomes unde-
tected from 2:1-HT-300-10 sample by Raman. There is a broad
peak from 2h = 10.0° to ca. 18.0° in 0.5:1-HT-300-10 sample
ascribed to HT B10H14 (Fig. S2) which implies the great excess of
(a) B 1s
190.0 eV
BN
187.8 eV
NaBH4
B
10H14 in this sample. Based on the abovementioned facts, it is con-
firmed that there are really two reactions exist between NaNH2
and B10H14: (a) xNaNH2+B10 14 ? yNaBH4 + zBN; (b) x’NaNH2 +
10H14 ? y’Na2B12H12, and Reaction (a) will turn to Reaction (b)
H
B
190
185
195
(b) N 1s
if with excess B10H14. It is not difficult to understand this phe-
nomenon because the produced NaBH4 will subsequently react
with excess B10H14 to produce Na2B12H12 and H2 as reported [19].
To confirm the exact equations of Reactions (a) and (b) and clar-
ify reaction mechanisms, the solid-state products of 5:1-HT-300-
10 sample is collected for XPS measurement (Fig. 2). The B 1 s spec-
tra show one peak at 187.8 eV ascribed to NaBH4 [23] and another
peak at 190.0 eV contributed from BN [22,24]. Meanwhile, the N 1
s XPS spectra only present one peak at 397.5 eV from BN which
means the N element in solid-state products only exists in the
compound of BN [22,24]. As a result, we propose the theoretical
reaction equation for producing NaBH4 as in Eq. (4):
397.5 eV
BN
402
400
398
396
394
392
Binding energy (eV)
Fig. 2. B 1 s (a) and N 1 s (b) XPS patterns of 5NaNH2 + B10H14 after heat treatment
at 300 °C for 10 h.
5NaNH2 þ B10H14 ! 5NaBH4 þ 5BN þ 2H2
ð4Þ
This reaction is well proved by the XRD and Raman signals
(Fig. 1). However, it is accurate only when the gas-state products
do not include N2 or other nitrides such as NH3 and N2H4, because
all the products of this reaction exist in either solid or gas phase in
sealed stainless steel crucibles. To investigate the real distribution
of the gas products, the produced gas of 5:1-HT-300-10 sample is
collected and GC spectrum using TCD is conducted (Fig. 3). The
results show that the first and only strong peak at ca. 1.36 min
from H2 is obviously observed. Peak analysis shows H2 has an occu-
pation of >99.30% which means H2 as the unique component in
gas-state products and a negligible production of other gases.
All of the abovementioned analysis unquestionably confirms
Reaction (a) happens via Eq. (4). Based on Eqs. (4) and (3) as
reported [19]propose the theoretical reaction equation for produc-
ing Reaction (b) can be easily decided as in Eq. (5):
Both XRD patterns and Raman spectra mainly indicate superposed
signals of starting materials of NaNH2 and B10H14 in HM sample
(Fig. S1) though with small amount of unidentified phase, which
means the HM process is generally physical mixture. When
2NaNH2 + B10H14 is heated at 300 °C for 10 h, all signal peaks from
starting materials in XRD and Raman disappeared (Fig. 1). XRD pat-
terns exhibit apparent formation of NaBH4 and Na2B12H12 while
Raman spectra show only signals of Na2B12H12 possibly due to
the different distribution state of Na2B12H12 (outer) and NaBH4
(inner). The results imply the reaction between NaNH2 and
B10H14 may be available for both NaBH4 and Na2B12H12 synthesis.
This exciting finding inspires and triggers us to investigate the
exact reaction equations for NaBH4 and Na2B12H12 production
and also to understand the reaction mechanisms.
A series of mixed starting materials with mol ratios of NaNH2:
B
10H14 from 5:1 to 0.5:1 was then HM and HT using the same
method. All the HM samples are only mixtures of NaNH2 and
10H14 (Fig. S1). Surprisingly, there is an obvious trend that the
10NaNH2 þ 7B10H14 ! 5Na2B12H12 þ 10BN þ 29H2
ð5Þ
B
Eq. (5) depicts the ideal situation in which the produced NaBH4
completely reacts with the excess B10H14 to form Na2B12H12. To
ensure the accuracy, the thermodynamics of both Eqs. (4) and (5)
are also considered. Standard formation enthalpy (kJ/mol) of start-
ing materials and products are firstly investigated (Table S1), then
the standard enthalpy changes and Gibbs free energy changes of
products of HT samples change from NaBH4 to NaBH4+Na2B12H12
and then to Na2B12H12 with the ratio of NaNH2:B10H14 decreasing
from 5:1 to 0.5:1. In 5:1-HT-300-10 sample, XRD indicates mostly
production of NaBH4 while Raman clearly shows the vibration
peaks of NaBH4 and a strong peak at 1373 cmꢂ1 contributed from
BN (Fig. 1) [21]. No BN signal is observed in XRD patterns implies
Eqs. (4) and (5) are evaluated (Table 1). Here,
DG is calculated
Fig. 3. GC spectrum using TCD for the evolved gases from 5NaNH2 + B10H14 after heat treatment at 300 °C for 10 h. (Inset shows the enlarged profile of peak at 1.358 min and
peak of H2 standard sample as reference; the table indicates the contribution of all detected peaks).

L. He et al. / Inorganica Chimica Acta 474 (2018) 16–21
19
Table 1
Standard enthalpy changes and Gibbs free energy changes of Eqs. (4) and (5)a.
11B MAS NMR
Equations
D
H298K
D
G298K
[BH4]-
Eq. (4)
Eq. (5)
ꢂ318.176
ꢂ441.116
ꢂ333.67
ꢂ553.46
2-
2-
[B12H12
]
a
All data are given in kJ/(mol NaNH2 or BN).
[B10H10
BN
]
overtone band
5:1
Fig. 4. Schematic illustration of the formation mechanisms of NaBH4 and
Na2B12H12
.
1:1
-60
using
D
G =
D
H ꢂ TDS at 298 K and DS (entropy change) is domi-
40
20
0
-20
ppm
-40
nated by the entropy of H2 gas (0.13 kJ/(Kꢀmol H2) [3]. The Gibbs
free energy changes of Eqs. (4) and (5) are ꢂ333.67 and ꢂ553.46
(kJ/mol NaNH2), respectively. Both of these negative values of
Gibbs free energy changes support the thermodynamic possibility
to synthesize NaBH4 and Na2B12H12 via Eqs. (4) and (5) as well.
In order to further confirm the veracity of Eq. (5), more synthe-
sis experiments via Eqs. (5) at different conditions are supple-
Fig. 5. 11B MAS NMR spectra of the mixtures of 5NaNH2 + B10H14 (5:1) and NaNH2
+ B10H14 (1:1) after heat treatment at 300 °C for 10 h.
decompose for NaH formation but the residual N and H elements
do not transform into NH3, N2 or others. The N-included interme-
diate is believed to react with B10H14 for BN production. The
decomposition mechanism of NaNH2 here is different from that
of the bulk one as reported to form H2 and N2 [25,26], which proves
the interaction between B10H14 and NaNH2. B10H14 simultaneously
decomposes into complicated borane mixture with smaller
skeletons such as B2H6, B3H7, B4H10, B5H11 and so on [27]. NaH
and N-included intermediate then react with smaller boranes to
form NaBH4 [28] and BN + H2 [29], respectively. Because the
decomposition of B10H14 is complicated and time-relied, many
NaH remains unreacted in 1 h heat treated sample (Fig. S6a). With
the increase of heat treatment time, B10H14 gradually decomposes,
therefore more NaH turns to NaBH4 and more N-included interme-
diate transforms into BN and H2. If with excess B10H14, the pro-
duced NaBH4 will further react with it to produce Na2B12H12. A
detailed schematic illustration of Reactions (a) and (b) are shown
in Fig. 4.
mented (Fig. S3). Three 1.43:1-HT samples (10NaNH2 + 7B10H14
)
with different reaction conditions all form mixtures of Na2B12H12
and NaBH4. Surprisingly, 1.43:1-HT-300-10 sample exhibits beau-
tiful Raman signals of Na2B12H12 but without any vibrations from
NaBH4 which indicates the main formation of Na2B12H12. Then,
the XRD patterns of a series of products with different starting ratio
reacted at the same condition (300 °C for 10 h, Fig. S4) are com-
pared. 1.43:1-HT-300-10 sample is found to well fit to the chang-
ing trend as presented in Fig. 1. It exhibits clear subtraction of
NaBH4 content compared with that in the sample of 2:1-HT-300-
10. The purity of Na2B12H12 is believed to be further improved
under optimized reaction conditions. In 1:1-HT-300-10 sample,
NaBH4 radiations in the XRD patterns disappear but a broad peak
between 2h = 10.0° and 18.0° from heated excess B10H14 begins
to form. These results mean the exact ratio of NaNH2:B10H14 for
Na2B12H12 production should be > 1:1 but <2:1 and confirm the
veracity of Eq. (5). In practical experiments, Na2B12H12 production
is affected by many factors and the mol ratio of 1.43:1 > NaNH2:
Though Eqs. (4) and (5) for NaBH4 and Na2B12H12 production are
confirmed, they only represent the theoretical and ideal situations.
In practical experiments, the products may be affected by different
synthesis conditions such as heating temperature, time and even
B10H14 > 1:1 is expected to produce Na2B12H12 with higher purity.
To understand the reaction mechanism for NaBH4 production,
5NaNH2 + B10H14 are heat treated at 300 °C for different time from
1 h to 10 h and their XPS spectra, XRD patterns and Raman spectra
are shown in Figs. S5 and S6. Survey XPS spectra show both
strengthening of NaBH4 and BN peaks from 1 h to 10 h of HT, indi-
cates that formations of both NaBH4 and BN are confined by the
decomposition speed of B10H14 and both processes are time-relied.
In XRD patterns of 1 h HT sample, there are clear NaH and NaBH4
radiation peaks but without signals of NaNH2 which means NaNH2
has already decomposed into NaH and N-included intermediate as
not detected. The N-included intermediate is possibly amorphous
A(NH)nA compounds such as Na2NH[25] since NaNH2 has to
size of reaction vessels. In order to synthesize NaBH4 and Na2B12
-
H12 with highest purities, different ratios of starting materials have
been HT at various conditions (Figs. S3–S4 and S6–S9). The main
B-H products and their corresponding reaction conditions are
listed in Table S2 for overall viewing. Based on the XRD and Raman
results, hitherto, 5:1-HT-300-10 and 1:1-HT-300-10 are optimal
conditions for synthesis of NaBH4 and Na2B12H12, respectively.
Samples synthesized at these two conditions are collected for 11B
MAS NMR analysis (Fig. 5). In 5:1-HT-300-10 sample, it is clearly
observed that there is a high and sharp peak at ꢂ42.2 ppm ascribed

20
L. He et al. / Inorganica Chimica Acta 474 (2018) 16–21
to [BH4]ꢂ, which indicates the main formation is NaBH4 [30,31]. A
low peak at ꢂ16.3 ppm is from Na2B12H12 [32]; two broad peaks
from ca. 10 to 30 ppm is originated from BN [10,19,33]. In 1:1-
HT-300-10 sample, the sharp peak at ꢂ15.8 ppm is ascribed to
Na2B12H12 which means the main formation is Na2B12H12. A low
peak at ca. ꢂ42.2 ppm is from residual NaBH4, two broad peaks
from ca. 8 to 30 ppm is from BN and two peaks at 2.2 & ꢂ30.7
ppm are originated from Na2B10H10 impurity [19,32]. The propor-
tions of different B-H products is studied by peak fitting
(Fig. S10) and their quantity distribution is listed in Table S3.
Though there still has certain amount of impurities in the currently
synthesized NaBH4 and Na2B12H12 samples, the synthesis method
is novel, interesting, facile and effective. In practical synthesis,
higher purities of NaBH4 and Na2B12H12 are hopeful to be obtained
by slightly decreasing/increasing B10H14 amount to NaNH2:B10H14
ratio as 5.1:1 or 5.2:1 and 1.3:1 or 1.2:1. Elevating HT temperature
SUSTech (No. 2015X18), JSPS KAKENHI Grant Number JP
15KK0212 and Macau FDCT (No. 118/2016/A3).
Appendix A. Supplementary data
Supplementary data associated with this article can be found, in
the online version, at https://doi.org/10.1016/j.ica.2018.01.010.
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and prolonging reaction time may be also effective for higher pur-
2ꢂ
ity of Na2B12H12 since B12
H
12
cluster is much more stable than
2ꢂ
B10
H
10
and BHꢂ4 clusters [34]; BN is a kind of important chemical
material and has many applications on high-temperature ceramics
equipment and as thermal conductors for its excellent stability and
thermal conductivity [35]; With appropriate solvents for BN and B-
H compounds separation, this synthesis method will undoubtedly
exhibit greater application perspective for not only BN but also B-H
compound synthesis and study in the future.
Notably, our preliminary study has confirmed this method is
also effective for Li2B12H12 and MgB12H12 synthesis, too. The details
will be addressed in the coming papers.
4. Conclusion
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In summary, we have developed a novel and facile solvent-free
method for synthesis of both NaBH4 and Na2B12H12 via simply
adjusting the ratio of NaNH2 to B10H14. The strategy of using equal
electronic body (NaNH2 vs. NaBH4) for synthesizing Na2B12H12 is
proposed and verified to be effective for the first time, which
implies the availability of synthesizing Na2B12H12 from B10H14
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and Na2B12H12 synthesis are confirmed and the reaction
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There are no conflicts of interest to declare.
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This work was partially supported by the National Natural
Science Foundation of China (No. 21671096, No. 21603094),
Shenzhen Key Laboratory Project (ZDSYS201603311013489),
the
Natural
Science
Foundation
of
Shenzhen
(No.
JCYJ20170412153139454, JCYJ20150331101823677), Science and
Technology Innovation Foundation for the Undergraduates of

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