Synthesis of [B12H12]2- based extractants and their application for the treatment of nuclear wastes

Article abstract of DOI:10.1016/S0022-328X(02)01540-1

Several closo-hydroborates bearing phosphite oxide, phosphine oxide or CMPO (carbamoylmethylphosphine oxide) groups, (Cs[(Ph₂P(O))₂N(H)B₁₂H₁₁] (1), = Octyl), Na[Bz₂N(H)B₁₂H₁₀OCH<

Full text of DOI:10.1016/S0022-328X(02)01540-1

Journal of Organometallic Chemistry 657 (2002) 83Á90
/
www.elsevier.com/locate/jorganchem
Synthesis of [B12H12]2ꢀ based extractants and their application for
the treatment of nuclear wastes
R. Bernard a, D. Cornu a,*, B. Gruner b, J.-F. Dozol c, P. Miele a, B. Bonnetot a
¨
a Laboratoire des Multimate´riaux et Interfaces (UMR CNRS 5615), UCB Lyon I, 43 Bd du 11 Novembre 1918, 69622 Villeurbanne Cedex, France
b Institute of Inorganic Chemistry, 250 68 Rez near Prague, Czech Republic
c CEA/DEN Cadarache/DED/SEP/LCD, 13308 Saint Paul lez Durance, France
Received 23 September 2001; accepted 23 April 2002
We have the pleasure to dedicate with affection this article to Pr. Henri MONGEOT on the occasion of his retirement, in recognition of his
outstanding contributions to boron chemistry
Abstract
Several closo-hydroborates bearing phosphite oxide, phosphine oxide or CMPO (carbamoylmethylphosphine oxide) groups,
Cs[(Ph2P(O))2N(H)B12H11] (1), K[Ph2P(O)CH2C(O)N(H)2B12H11] (2), Na[Bz2N(H)B12H10OCH2CH2OCH2CH2P(O)(OBu)2] (5),
Na[Bz2N(H)B12H10O(CH2)4N(R)C(O)CH2P(O)(Ph)2] (9, Rꢁ
/
Pri ; 10, Rꢁ
/
Octyl), Na[Bz2N(H)B12H10OCH2CH2OCH2-
CH2N(Bui )C(O)CH2P(O)(Ph)2]ꢀ (11) were synthesised employing novel neutral bipolar intermediates [Bz2N(H)B12H10O(CH2)4]
(3) and [Bz2N(H)B12H10O(CH2CH2)2O] (4) as useful synthons. All new compounds were characterised by NMR spectroscopy and
mass spectrometry techniques. Their abilities to extract selectively the radionuclides 241Am and 152Eu from nuclear waste solutions
were investigated using a liquidÁ/liquid extraction technique. Promising results were obtained with compound 10, which exhibits
enhanced hydrophobicity and solubility in organic extraction solvent. # 2002 Elsevier Science B.V. All rights reserved.
Keywords: Hydrododecaborate; Oxonium; CMPO; LiquidÁliquid extraction; Nuclear waste
/
1. Introduction
One technique which could be adopted for this
treatment are hydrometallurgical methods based on
the liquidÁliquid extraction using molecules capable to
selectively bind the target nuclides and transport them
to organic phase. In this field, we focused our attention
on the selective complexation of trivalent cations from
the lanthanide and actinide series, especially 152Eu and
241Am.
There has been considerable continuous interest in the
selective separation of long lived radionuclides from
radioactive waste. Presently high activity (HA) liquid
waste arising from Purex process which contain b/g
emitters such as: Tc, Se, Cs, etc. or a emitters such as
transuranium elements: Np, Am, Cm, are vitrified
before long term storage or disposal. It should be of
interest to selectively remove long lived from HA waste
in order to destroy them by advanced transmutation
techniques. Transmutation operations require pure
targets; in particular trivalent actinides such as amer-
icium or curium have to be separated from other fission
products and especially from lanthanides.
/
Many organic molecules of different constitution have
been tested for this application [1Á4] (namely crown
/
ethers, functionalised calixarenes, CMPO (carbamoyl-
methylphosphine oxide), etc.). By comparison to these
neutral extractants, hydroborate derivatives present the
advantage of forming neutral compounds (ion pairs)
with the cationic radionuclides. The resulting ion pairs
can be extracted to organic solvents of medium polarity.
Even if the cobaltadicarbollide anions (COSAN deriva-
tives) [5] are the most extensively studied compounds,
hydrododecaborate derivatives based on [B12H12]2ꢀ
anion can represent interesting alternative in respect to
* Corresponding author. Tel.: ꢂ
18.
E-mail address: cornu@univ-lyon1.fr (D. Cornu).
/
33-472-4484 03; fax: ꢂ33-472-4406
/
0022-328X/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
PII: S 0 0 2 2 - 3 2 8 X ( 0 2 ) 0 1 5 4 0 - 1

84
R. Bernard et al. / Journal of Organometallic Chemistry 657 (2002) 83Á90
/
their high stability, lower price and better availability.
The parent compound can be functionalised by one or
two suitable groups to create resulting monovalent
anions containing metal selective groups and hydro-
phobic enough to transfer the cations into organic
phase. The structure of thus obtained anions is different
from selective extraction agents based on COSAN
moiety, and may, in principle afford another selectivity
during the extraction process.
Starting from the closo-dodecahydrododecaborate
[B12H12]2ꢀ anion, synthetic methods for above species
were developed with the aim of obtaining hydrophobic
anions bearing substituents known for their ability to
complex radionuclides of the lanthanide and actinide
series. For this specific application, functionalities con-
taining phosphorous oxide groups bonded on organic
molecules like calixarenes [4] or even used alone [2] are
known to be powerful sequestering agents for these
metals. It seemed of particular interest to combine
favourable extraction properties of such groups with
these of our hydrophobic anions in one molecule. For
this reason, we focused our attention on the preparation
of hydroborate anions bearing ligand containing R2P(O)
functions, namely phosphine oxide, phosphite oxide and
CMPO like groups.
phobicity of the anion and (2) complex selectively
cations. In the second series (B), the cage is bearing
two different groups, one for each expected properties.
2.1. Syntheses of hydrododecaborate derivatives 1 and 2
(A type extractants)
As we have found, both chlorodiphenylphosphine and
p-nitrophenyl(diphenylphosphoryl)-acetate react with
[NH3B12H11]ꢀ in the presence of sodium hydride
yielding
[(Ph2P(O))2N(H)B12H11]ꢀ
(1)
and
[Ph2P(O)CH2C(O)N(H)2B12H11]ꢀ (2), respectively
(Scheme 1).
Both monoanions 1 and 2 were fully characterised by
NMR spectroscopy and mass spectrometry. Compound
1 would originate from a two step process. First,
[NH3B12H11]ꢀ was reacted under argon atmosphere
with a large excess of ClPPh2 to give presumably the
corresponding monoanion [(Ph2P)2N(H)B12H11]ꢀ as an
intermediate. This compound was without isolation
converted to target compound 1 by oxidation, which
readily took place in contact with air. A large excess of
chlorophosphine was used to improve the yield of the
disubstituted product. Even under these forced condi-
tions, final product contained nearly 15% of monosub-
stituted derivative Cs[Ph2P(O)N(H)2B12H11] according
to 1H-NMR spectrum. The separation of these two
compounds by chromatography was unsuccessful. On
the other hand, the solubility of sample containing both
compounds in the above ratio in the organic solvent
2. Results and discussion
Hydrododecaborate derivatives due to their high
stability and weak nucleophilicity possess versatile
properties and solution behaviour suitable for broad
range of possible applications. These range from the
most studied applications for Boron neutron capture
therapy (BNCT) [6], to presently studied interesting
potential for the preparation of non-linear optical
(NLO) materials [7], and also for the synthesis of
extractants. For our specific application, classical
typically used for liquidÁliquid extraction (NPOE, o-
/
nitrophenyloctyl ether or NPHE, o-nitrophenylhexyl
ether) was too low to perform extraction test.
Compound 2 is to our knowledge the first example of
[B12H12]2ꢀ anion bearing a CMPO like function. As
described above for 1, the reaction gave a mixture of
monosubstituted anion 2 and one other species was
obtained. From this mixture, compound 2 could be
separated by chromatography. The solubility of com-
pound 2 in above organic solvents is much higher than
that for 1. It is also of interest to notice that the
substitution reaction, in that case, seems to be slower
and 4 days reaction time is necessary. Moreover, 2
exhibits an extraordinary solubility for a monoanion
even in aqueous media. Therefore, we can assume that
the nitrogen atom bound in the amidic function would
have a lower basicity and thus would tend to be less
protonized comparing to the classical nitrogen atoms
bound to a cage. According to this assumption, 2 would
behave rather as a divalent anion in solution. This effect
apparently leads to enhanced solubility of this com-
pound in water, and negative results from the extraction
tests.
liquidÁliquid extraction technique requires extractants,
/
which combine good solubility in the organic phase,
hydrophobicity and selectivity.
Hydrododecaborate dianions are known for their
good solubility in aqueous phase, therefore the overall
charge of the cluster should be first decreased from ꢀ
/
2
to ꢀ1 creating monoanions being known to be more
/
prone to leave water and enter the organic phase. For
this purpose, we have used the ability of [B12H12]2ꢀ to
react with hydroxylamine-O-sulfonic acid yielding the
useful intermediate [NH3B12H11]ꢀ [8]. Moreover, the
amino hydrogen atoms of that anion can be replaced by
suitable groups (alkyl, aryl, . . .) when forced reaction
conditions are used [9].
Two different routes have been investigated which
lead to two diversified groups of extractants (Fig. 1). In
the A group, hydrododecaborate cluster is bearing only
one substituent which should (1) improve the hydro-

R. Bernard et al. / Journal of Organometallic Chemistry 657 (2002) 83Á
/90
85
2ꢀ
Fig. 1. Two different types of extractants derived from [B12H12
]
.
2.2. Syntheses of hydrododecaborate derivatives 5, 9, 10
and 11 (B type extractants)
The preparation of disubstituted monoanions was
carried out by a similar procedure as described for the
oxonium derivatives prepared for BNCT application.
Recently, Sivaev et al. [6] have shown that [B12H12]2ꢀ
yields
to
[B12H11O(CH2)4]ꢀ
or
[B12H11O(CH2CH2)2O]ꢀ by a ‘solvent (THF or 1,4-
dioxane, respectively) addition’ reaction in presence of
Et2O×/BF3 as acid catalyst. Ring opening reactions under
nucleophilic attacks have also been reported [6,10].
As we have found, oxonium derivatives of monosub-
stituted hydrododecaborate can be obtained following
slightly modified procedure to that described above for
the parent [B12H12]2ꢀ anion. Starting from the free
conjugated acid form of the already described hydro-
phobised dibenzylamino [Bz2N(H)B12H11]ꢀ anion [9],
acid promoted reaction occurred under reflux. These
reactions led to the bipolar neutral species 3 and 4
(Scheme 2).
Scheme 2.
It is important to notice that the main difference
between these reactions and those described with
[B12H12]2ꢀ is the nature of the acid catalyst. Since no
further purification is needed in this case, the proton of
Scheme 1.

86
R. Bernard et al. / Journal of Organometallic Chemistry 657 (2002) 83Á90
/
the conjugated acid instead of Et2O×
/
BF3 can serve with
Compounds 5 and 10 exhibit a very good solubility in
organic solvents like NPOE or NPHE. Their abilities to
extract selectively 241Am and 152Eu from simulated
nuclear waste have been investigated and will be
described below. But, unfortunately, compounds 9 and
11 have strong hydrophobic natures but their few
solubility in extraction solvent (NPOE and NPHE) do
not allow to measure their extraction abilities.
advantage as promoter for this reaction in aprotic
solvent. The dioxanate derivative 4 has been obtained
with a lower yield similarly to what has been mentioned
for [B12H12]2ꢀ [6].
The bipolar species 3 and 4 containing oxonium
oxygen have been fully characterised by mass spectro-
metry and NMR spectroscopy. 11B-NMR results sug-
gest that 3 and 4 are mixtures of at least two positional
isomers, probably of the minorite amount of 1,2- and
main 1,7-isomer. Pattern in the 11B-NMR spectra
correspond to this reported already for the analogous
disubstituted hydrododecaborate [1-Bz2N(H)B12H10-7-
C10H7]ꢀ [9]. Nevertheless, the chemical shift of the
boron atom bound to the dibenzylamino group is
2.3. Extraction of 241Am(III) and 152Eu(III)
As it has been mentioned above, only compounds 5
and 10 have been tested. The results obtained have been
reported in Tables 1 and 2. The values of the distribu-
tion coefficients of 241Am and 152Eu have been measured
for different acidity of the aqueous phase.
Tables 1 and 2 show that both extractants 5 and 10
present a remarkable efficiency in low acidity medium
(0.01 M HNO3). Moreover, promising results have been
obtained with 10, which exhibits a strong efficiency for
acidity up to 0.1 M HNO3. In any case, the results
shifted
downfield
compared
to
parent
[Bz2N(H)B12H11]ꢀ ion, presumably due to oxygen
substitution in a second apical position.
We assume that 3 and 4 are convenient precursors for
the preparation of bifunctional hydrododecaborate
derivatives for many applications.
Several ring cleavage reactions by a suitable nucleo-
phile, proceeding on a-carbon atom of the THF or 1,4-
dioxane have been investigated (Scheme 3), leading to
extractants 5, 9, 10 and 11 with functional groups
bonded via 6, 7 or 8 atom pendant group.
Table 1
Distribution coefficients for 152Eu and 241Am measured with 5 (organic
phase, 10ꢀ2 M 5 in NPHE; aqueous phase HNO3).
Acidity (M)
D (152Eu)
D (241Am)
All these extractants have been fully characterised by
mass spectrometry and NMR spectroscopy. In 1H-
NMR spectra, the chemical shifts of protons belonging
to CMPO like groups correspond with those reported
for CMPO substituted calixarene [4].
0.01
0.1
1
ꢀ100
1.45
0.06
ꢀ100
3.5
0.09
Scheme 3.

R. Bernard et al. / Journal of Organometallic Chemistry 657 (2002) 83Á
/90
87
Table 2
Distribution coefficients for 152Eu and 241Am measured with 10
(organic phase, 10ꢀ2 M 10 in NPHE; aqueous phase HNO3)
at 300 MHz, respectively. The following abbreviations
are used: s, singlet; d, doublet; m, multiplet; u, un-
resolved signal. Mass spectrometry measurements were
performed in the Mass Spectrometry Laboratory, Cen-
tral Analytical Service of the CNRS, Solaize (France). A
hybrid mass spectrometer ZAB-2-SEQ (Micros) was
used for the analyses by SIMS technique. Other
measurements were performed using the electrospray
(ES) method on a VG-platform micromass spectro-
meter. Samples were introduced in the spectrometer as
MeCN or C3H6O solutions.
Acidity (M)
D (152Eu)
D (241Am)
0.01
0.1
1
ꢀ100
ꢀ100
2.1
ꢀ100
ꢀ100
3.5
3
0.85
1.2
obtained with 241Am are slightly upper than those
obtained with 152Eu.
On one hand, the values obtained for low acidity
medium are larger than those measured in similar
conditions by using rather CMPO derivatives [2] or
calixarenes [4] or cavitands [3] based extractants. On the
other hand, the latter are much more efficient than both
compounds 5 and 10 for high acidity medium. There-
fore, these hydroborate based compounds represent
interesting supplementary extractants for high efficiency
extraction in a wide range of acidity medium.
Despite a possible degradation of the cluster at high
acidity medium, the dependence of the distribution
coefficients on the acidity of the aqueous phase can be
related to the overall extraction equilibrium constant
(KEx) as it is proposed in Fig. 2.
3.2. Synthesis of Cs[(Ph2P(O))2N(H)B12H11] (1)
(Et3HN)2B12H12 was converted to (Me3HN)2B12H12
by passing on a C20 H Duolite resin charged with
protons
following
by
addition
of
Me3N.
(Me3HN)2B12H12 was converted by reaction with aq.
hydroxylamine-O-sulfonic acid into the monoamino
derivative (Me3HN)[B12H11NH3] as described in the
literature [8].
Solid (Me3HN)[B12H11NH3] (1.278 g, 5.87 mmol) was
dried overnight at 70 8C under vacuum. Freshly
distilled THF (100 ml) and NaH (0.704 g, 29.33 mmol)
were introduced into the reaction flask under anhydrous
conditions. The mixture was stirred for 3 h at room
temperature (r.t.) and then refluxed for 30 min. A
solution of chlorodiphenylphosphine (12.943 g, 58.70
mmol, 11 ml) in 20 ml THF was slowly added dropwise
(30 min). The mixture was allowed to cool down to r.t.
and then THF was distilled in vacuo. After dissolution
Measurements reported in Tables 1 and 2 clearly
confirm these assumptions and a rapid decrease of the
distribution coefficients is observed when acidity in-
creases.
in a waterÁMeCN mixture, the product was passed on a
/
3. Experimental
C20 H Duolite resin charged with protons and con-
verted into Cs salt by addition of CsOH yielding 1.68 g
of solid in which the disubstituted compound 1 is the
major product according to NMR results.
The product was analysed by 11B-, 1H-NMR spectro-
scopy, FTIR and mass spectrometry. Mass spectrometry
3.1. Starting materials and instruments
All sensitive compounds were handled under atmo-
sphere of pure Ar using vacuum-line, Schlenk techni-
ques and an efficient dry box with solvents purified by
standard methods [11]. (Et3HN)2B12H12 was provided
by KATCHEM Ltd., Prague. 11B-, 31P- and H-NMR
spectra were recorded on a Bruker AM300 spectrometer
in CD3CN or (CD3)2CO at 96.29 MHz with Et2O×
as external reference (positive values downfield), at
146.2 MHz with 85% H3PO4 as external reference and
clearly showed the presence of [(Ph2P(O))2Ã
B12H11]ꢀ and [Ph2P(O)Ã B12H11]ꢀ.
NH2Ã
FTIR (cmꢀ1): 3220 (NH), 2490 (BH), 1165 (PO); 11B-
NMR (d, ppm, CH3CN): ꢀ6.5 (s, B), ꢀ15.6 (d, 5B), ꢀ
16.5 (d, 5B), ꢀ
19.7 (d, B); 1H-NMR (d, ppm, CD3CN):
7.49Á7.87 (m,18.5H, CH), 4.97 (s, 1.15H, NH), 1.1Á1.7
(u, 11H, BH); MS (m/z): 358 [Ph2P(O)ÃNH2Ã
B12H11]ꢀ,
558 [1]ꢀ.
/
NHÃ
/
/
/
1
/
/
/
/BF3
/
/
/
/
/
3.3. Synthesis of K[Ph2P(O)CH2C(O)N(H)2B12H11]
(2)
p-Nitrophenyl(diphenylphosphoryl)acetate, Ph2P(O)-
CH2C(O)OC6H4NO2, was prepared by the reaction of
diphenylphosphorylacetic acid with p-nitrophenol and
thionyl chloride in dry CHCl3 as described in the
literature [4].
Fig. 2. Relation between the distribution coefficient (DM) and the
acidity of the aqueous phase (Kex: extraction equilibrium constant).

88
R. Bernard et al. / Journal of Organometallic Chemistry 657 (2002) 83Á90
/
In a typical experiment, 1.0 g of (Me3HN)[B12-
solution of NH4NO3 as eluent (RF 0.15, product; RF 0.6,
0.8, impurities). This separation yielded [Bz2N(H)-
B12H10O(CH2)4] (0.98 g, 54%) as white crystals.
H11NH3] (4.60 mmol) was dried overnight as described
above and then dissolved in 100 ml of freshly distilled
THF. Sodium hydride (0.4 g, 16.7 mmol) was added
slowly to the solution until no gas evolution was
FTIR (cmꢀ1): 3231 (NH), 3042Á
/
2874 (CH), 2503
(BH); 11B-NMR (d, ppm, C3H6O): 5.6 (s, 1B, BO), ꢀ
/
2.2
1
observed.
p-Nitrophenyl(diphenylphosphoryl)acetate
(s, 1B, BN), ꢀ
NMR (d, ppm, (CD3)2CO): 6.9Á
CH), 5.0 (m, 3H, benzyl CH2ꢂNH), 4.4 (m, 4H, THF
CH2), 4.1 (d, 2H, benzyl CH2), 2.1 (m, 4H, THF CH2),
1.2Á1.7 (u, 10H, BH); MS (ES, m/z): 409.4 [M].
/
17.8Á
/
ꢀ
/
18.3 (m, 9B), ꢀ
/
20.6 (d, 1B); H-
(1.77 g, 4.65 mmol) were introduced into reaction flask
under Ar atmosphere. The mixture was stirred 4 days at
/7.3 (m, 10H, benzyl
/
r.t. and then cooled down to ꢀ
/
10 8C. Then 50 ml of a
MeOHÁwater (1/1) solution was added slowly. The
/
/
solution was concentrated under vacuum and the
anionic products were precipitated as tetramethylam-
monium salts by the addition of an excess of tetra-
methylammonium chloride. NMR analyses showed that
the residue contained a mixture of [Ph2P(O)CH2-
C(O)N(H)2B12H11] (2) and another product which was
not fully characterised. Compound 2 was purified by
chromatography performed with a glass column filled
3.5. Synthesis of [Bz2N(H)B12H10O(CH2CH2)2O] (4)
This bipolar neutral derivative was obtained by
following the same procedure as described above and
with using 1,4-dioxane instead of THF. It is important
to note that the yield (41%) is lower in that case. This
with silicagel (70Á
/
230 mesh, Aldrich) with CH2Cl2Á
/
1
compound was analysed by 11B- and H-NMR spectro-
MeCN (3/1) as eluent. The separation was monitored
by TLC on DEAE cellulose [12] with 2 M aq. solution of
NH4NO3 as eluent. The spots were detected by spraying
with a solution of PdCl2 (0.5% in 5% HCl). Pure
compound 2 was finally obtained 1.23 g, (yield: 61%).
scopy and mass spectrometry. No significant difference
has been noticed between the 11B-NMR spectrum of
these two bipolar neutral species.
11B-NMR (d, ppm, C3H6O): 5.6 (s, 1B, BO), ꢀ
2.2 (s,
/
1
1B, BN), ꢀ
NMR (d, ppm, CDCl3): 6.9Á
4.9 (m, 3H, benzyl CH2ꢂNH), 4.0 (d, 2H, benzyl CH2),
3.7 (m, 8H, dioxane CH2), 1.2Á1.7 (u, 10H, BH); MS
(ES, m/z): 425.4 [M].
/
17.8Á
/
ꢀ
/
18.3 (m, 9B), ꢀ
/
20.6 (d, 1B); H-
FTIR (cmꢀ1): 3235 (NH), 3059Á
(BH), 1542 (CO), 1162 (PO); 31P-NMR (d, ppm,
C3H6O): 33.7; 11B-NMR (d, ppm, C3H6O): ꢀ
5.18 (s,
1B), ꢀ15.16 (d, 5B, B(7Á11)), ꢀ16.12 (d, 5B, B(2Á6)),
18.60 (d, 1B); H-NMR (d, ppm, (CD3)2CO, D2O):
7.44Á7.80 (m, 10H, aromatic CH), 5.7 (s, ca. 1H, NH),
4.1 (d, 2H, P(O)CH2C(O)), 1.16Á1.46 (u, 11H, BH); MS
(m/z): 306 [2-C6H5Ã
O]ꢀ.
/
2853 (CH), 2488
/7.3 (m, 10H, benzyl CH),
/
/
/
/
/
/
/
1
ꢀ
/
/
/
/
3.6. Synthesis of [Bz2N(H)B12H10OCH2CH2OCH2-
CH2P(O)(OBu)2]Na (5)
3.4. Synthesis of [Bz2N(H)B12H10O(CH2)4] (3)
Commercial dibutyl phosphite, (BuO)2P(O)H (0.187
g, 0.96 mmol), was converted into its Na salt by reaction
with NaH (24 mg, 1.0 mmol) in dry THF (50 ml). This
solution was added slowly at r.t. to a solution of 4 (0.39
g, 0.92 mmol) in dry THF. The mixture was stirred at
The hydrophobic monoanion [Bz2N(H)B12H11]ꢀ was
prepared and purified following the method previously
described by our group [9].
In a typical experiment, Me4N[Bz2N(H)B12H11] was
first converted into its conjugate acid by overlaying a
suspension of the tetramethylammonium salt in 150 ml
of HCl (4 M) by Et2O (50 ml). The organic layer was
r.t. overnight. Thirty millilitres of a solution MeOHÁ
/
water (1/1) was added slowly. The solution was con-
centrated under vacuum and precipitated as tetramethy-
lammonium salt by adding a large excess of NMe4Cl.
separated and the aq. phase was washed with 3ꢃ30 ml
/
of Et2O. The combined organic phases were carefully
evaporated in vacuo at r.t. yielding a glassy yellow solid
H[Bz2N(H)B12H11].
All the following experiments were performed under
Ar atmosphere. H[Bz2N(H)B12H11] (1.5 g, 4.43 mmol)
was dissolved into 50 ml of freshly distilled THF. The
solution was refluxed for 2 h yielding the title bipolar
neutral compound and anionic impurities. Then 30 ml of
THF were evaporated under vacuum and the product
was purified by chromatography performed with a glass
Then after dissolution in a waterÁMeCN mixture, the
/
product was passed on a C20 Hꢂ Duolite resin charged
with protons and converted into Na salt by addition of
NaOH (yield: 0.50 g, 85%).
11B-NMR (d, ppm, C3H6O): 4.6 (s, 1B, BO), ꢀ
1B, BN), ꢀ17.8Á 18.6 (m, 9B), ꢀ
NMR (d, ppm, CDCl3): 31.7; 1H-NMR (d, ppm,
CDCl3): 6.9Á7.4 (m, 10H, benzyl CH), 5.0 (m, 3H,
benzyl CH2ꢂNH), 4.1 (d, 6H, benzyl CH2ꢂ
OCH2CH2CH2CH3), 3.7Á3.9 (m, 8H, dioxane CH2),
/3.1 (s,
/
/
ꢀ
/
/
23.7 (d, 1B); 31P-
/
/
/
/
column filled with silicagel (70Á
CH2Cl2ÁMeCN (3/1) as eluent. The separation was
monitored by TLC on DEAE cellulose [12] with 2 M aq.
/
230 mesh, Aldrich) with
1.67 (m, 4H, OCH2CH2CH2CH3), 1.43 (m, 4H,
OCH2CH2CH2CH3), 0.95 (t, 6H, OCH2CH2CH2CH3),
/
1.2Á
1.7 (u, 10H, BH); MS (FABꢀ, m/z): 617.4 [5]ꢀ.
/

R. Bernard et al. / Journal of Organometallic Chemistry 657 (2002) 83Á
/90
89
3.7. Synthesis of (R)HNC(O)CH2P(O)(Ph)2 (6, Rꢁ
/
tracted with CHCl3 (3ꢃ100 ml) by washing the aq.
/
Pri; 7, Rꢁ Bui)
/
solution. The organic solution was evaporated to
dryness under vacuum giving pure 9 (resp. 10) (yield:
ca. 0.49 mmol, ca. 51%).
In a typical experiment, p-nitrophenyl(diphenylpho-
sphoryl)acetate [4] was dissolved in a large excess of
isopropylamine or isobutylamine, respectively. The
solution was stirred at r.t. overnight. Then excess of
alkylamine was eliminated under vacuum and the
product was recrystallised from hot MeOH (yield: 92%
(6) and 89% (7)). These amides have been characterised
9: 11B-NMR (d, ppm, C3H6O): 5.8 (s, 1B, BO), ꢀ
4.2
/
1
20.0 (d, 1B); H-
7.21 (m, 20H, ArH), 5.02
(s, 1B, BN), ꢀ
NMR (d, ppm, CDCl3): 7.85Á
/
16.1Á
/
ꢀ
/
18.6 (m, 9B), ꢀ
/
/
(d, 2H, benzyl CH2), 4.05 (d, 2H, benzyl CH2), 3.24 (d,
2H, OCH2CH2CH2CH2N), 3.10 (m, 1H, Pri CH), 2.81
(m, 2H, OCH2CH2CH2CH2N), 1.43 (m, 4H,
1
by FTIR and H-NMR spectroscopy.
OCH2CH2CH2CH2N), 1.07 (m, 6H, Pri CH3), 1.15Á
/
1H-NMR (d, ppm, CDCl3): 6: 7.83Á
/
7.51 (m, 10H,
ArH), 3.58 (d, 2H, P(O)CH2C(O)), 3.0 (d, 6H, CH3), 1.0
(m, 1H, CH); 7: 7.81Á7.50 (m, 10H, ArH), 3.62 (d, 2H,
1.79 (u, 10H, BH); MS (FABꢀ, m/z): 708 [9]ꢀ.
10: 11B-NMR (d, ppm, C3H6O): 5.8 (s, 1B, BO), ꢀ
/
4.0
1
20.9 (d, 1B); H-
7.21 (m, 20H, ArH), 4.98
/
(s, 1B, BN), ꢀ
/
16.2Á
/
ꢀ
/
18.9 (m, 9B), ꢀ
/
P(O)CH2C(O)), 3.32 (m, 2H, NCH2CH(CH3)2), 1.95 (m,
1H, NCH2CH(CH3)2), 1.10 (m, 6H, NCH2CH(CH3)2);
NMR (d, ppm, CDCl3): 7.85Á
/
(d, 2H, benzyl CH2), 4.10 (d, 2H, benzyl CH2), 3.40 (m,
2H, octyl CH2), 3.24 (d, 2H, OCH2CH2CH2CH2N),
3.08 (m, 2H, octyl CH2), 2.81 (m, 2H,
FTIR (cmꢀ1) 6 and 7: ca. 3290 (NH), ca. 3060Á
2850
(CH), ca. 1540 (CO), ca. 1160 (PO).
/
OCH2CH2CH2CH2N),
1.43
(m,
4H,
OCH2CH2CH2CH2N), 1.29 (m, 12H, octyl CH2),
3.8. Synthesis of
(CH3(CH2)7)HNC(O)CH2P(O)(Ph)2 (8)
1.79Á1.15 (u, 10H, BH), 0.91 (t, 3H, octyl CH3); MS
/
(FABꢀ, m/z): 780 [10]ꢀ.
Octylamine (0.68 g, 5.27 mmol) was dissolved in 100
ml of EtOH free dry THF. p-Nitrophenyl(diphenylpho-
sphoryl)acetate (2.34 g, 6.14 mmol) was added slowly in
the reaction flask. The mixture was stirred at 45 8C
during 72 h. Then the solution was cooled down to r.t.
and 80 ml of water was added slowly. The organic phase
containing the product was extracted and the aq. phase
3.10. Synthesis of Na[Bz2N(H)B12H10(OCH2CH2)2-
N(Bui)C(O)CH2P(O)(Ph)2] (11)
Compound 11 was prepared following the same
procedure described above, using 4 instead of 3 and 7
instead of 6 (or 8). The yield obtained (53%) is similar to
those obtained for 9 and 10.
was washed with 3ꢃ20 ml of CHCl3. The combined
/
organic phases were dried with anhydrous Na2SO4 and
subsequently evaporated to dryness yielding crude
product 8, which was purified by recrystallisation from
hot MeOH (30 ml) (yield: 2.10 g, 92%). The FTIR
spectrum of 8 exhibits no significant difference com-
pared to those of 6 and 7, except of course for the bands
relative to the alkyl groups.
11B-NMR (d, ppm, C3H6O): 5.3 (s, 1B, BO), ꢀ
1B, BN), ꢀ16.9Á 19.2 (m, 9B), ꢀ21.3 (d, 1B); H-
NMR (d, ppm, CDCl3): 7.85Á7.21 (m, 20H, ArH), 4.98
(d, 2H, benzyl CH2), 4.10 (d, 2H, benzyl CH2), 3.9Á3.7
/
3.9 (s,
1
/
/
ꢀ
/
/
/
/
(m, 6H, dioxane CH2), 3.30 (m, 2H, NCH2CH(CH3)2),
2.81 (m, 2H, OCH2CH2N), 1.95 (m, 1H,
NCH2CH(CH3)2), 1.79Á
/
1.15 (u, 10H, BH), 1.10 (m,
6H, NCH2CH(CH3)2); MS (FABꢀ, m/z): 739 [11]ꢀ.
1H-NMR (d, ppm, CD2Cl2): 7.85Á
7.51 (m, 10H,
/
ArH), 3.58 (d, 2H, P(O)CH2C(O)), 3.29 (m, 2H, octyl
CH2), 1.36 (m, 12H, octyl CH2), 0.93 (t, 3H, octyl CH3).
3.11. LiquidÁ
/
liquid extraction of actinides and
lanthanides
3.9. Synthesis of K[Bz2N(H)B12H10O(CH2)4N-
Pri, 10, Rꢁ
(R)C(O)CH2P(O)(Ph)2] (9, Rꢁ
/
/octyl)
The tests were performed on simulated waste solu-
tions which consist in 4 mol lꢀ1 HNO3 spiked with
152Eu and 241Am. The activity was 1500 kBq lꢀ1 which
Both title compounds were prepared following the
same procedure. In a typical experiment, 1.58 mmol of
well dried 6 (respectively 8) were dissolved in 50 ml of
freshly distillated THF. Sodium hydride (2.2 mmol,
0.053 g) was added slowly to the solution under stirring.
Gaz evolution was observed. The mixture was stirred 1 h
at r.t. Then a solution of 0.40 g of 3 (0.97 mmol) in dry
THF (50 ml) was added dropwise to the reaction flask.
The solution was stirred 5 h at r.t., and then refluxed 5
h. After cooling, the excess of NaH was removed by the
addition of 30 ml of EtOH and 30 ml of water. The
solution was concentrated and the product was ex-
corresponds to the following concentration [Eu]ꢁ
/
1.5ꢃ
/
10ꢀ9, [Am]ꢁ 10ꢀ8. A 10ꢀ3 mol lꢀ1 solution of
/
5.2ꢃ
/
the extractant in NPHE or NPOE was used as the
organic phase. Equal volumes (1 ml) of both phases
were shaken in sealed tubes for 1 h. The concentration
of actinides in each phase was determined by liquid
scintillation using a Tri Carb liquid scintillation analyser
(Packard, a Canberra Company) [13]. Therefore, 0.100
ml of each phase was added to 19.9 ml of a scintillating
liquid (insta gel) before the measurements. The distribu-
tion coefficients of the cations are defined by D where

90
R. Bernard et al. / Journal of Organometallic Chemistry 657 (2002) 83Á90
/
a[Morg] and a[Maq] denote the total concentration of
metal species in the organic and in the aq. phase,
References
[1] J.-F. Dozol, F. Lopez Calahorra, A. Mc Kervey, V. Boehmer, R.
Ungaro, M.J. Schwing, F. Arnaud, D. Reinhaoudt, G. Wipff, in:
T. McMenanmin (Ed.), Fourth European Conference on Man-
agement and Disposal of Radioactive waste EUR 17543, Lux-
embourg, 1997.
respectively.
P
[Morg
]
Dꢁ
P
[Maq]
[2] (a) E.P. Horwitz, H. Diamond, K.A. Martin, Solvent Extr. Ion
Exch. 4 (1986) 449;
(b) E.P. Horwitz, D.G. Kalina, L. Kaplan, G.W. Mason, H.
Diamond, Sep. Sci. Technol. 17 (1982) 1261;
4. Conclusion
(c) P. Beudaert, V. Lamare, J.-F. Dozol, L. Troxler, G. Wipff, J.
Chem. Soc. Perkin Trans. 2 (1999) 2515 (and references therein).
[3] (a) H. Boerrigter, T. Tomasberger, W. Verboom, D.N. Rein-
houdt, Eur. J. Org. Chem. (1999) 665;
Two types of functionalised cluster derivatives were
prepared starting from closo-dodecahydrododecaborate
anion. It seems that the simultaneous control of both
most important factors i.e. solubility and hydrophobi-
city is difficult to reach by introducing only one
substituent into the molecule like in the A type anions.
Promising results have been obtained for the B type
anions, and especially for compound 10. In any case, the
crucial step is to obtain cluster anions soluble in the
organic extraction solvent. As it has been established in
Fig. 2, a good solubility of the extractant, which permit
to increase its concentration in solution, should com-
pensate the effect of the acidity. Since a wide range of
chemical modifications can be applied to such deriva-
tives, on the basis of the results obtained with com-
pound 10, further attention will be focused on
modifying the nature of the substituents with the aim
of increasing selectivity, solubility and therefore effi-
ciency of our extractants.
(b) H. Boerrigter, W. Verboom, D.N. Reinhouldt, J. Org. Chem.
62 (1997) 7148.
[4] (a) T.N. Lambert, G.D. Jarvinen, A.S. Gopalan, Tetrahedron
Lett. 40 (1999) 1613;
(b) S. Barboso, A. Garcia Carrera, S.E. Matthews, F. Arnaud-
Neu, V. Bohmer, J.-F. Dozol, H. Rouquette, M.-J. Schwing-
¨
Weill, J. Chem. Soc. Perkin Trans. 2 (1999) 719 (and references
therein);
(c) F. Arnaud-Neu, V. Bohmer, J.-F. Dozol, C. Gruttner, R.A.
¨
¨
Jakobi, D. Kraft, O. Mauprivez, H. Rouquette, M.-J. Schwing-
Weill, N. Simon, W. Vogt, J. Chem. Soc. Perkin Trans. 2 (1996)
1175.
[5] (a) P. Selucky, J. Plesek, J. Rais, M. Kyrs, L. Kadlecova, J.
Radioanal. Nucl. Chem. Articles 149 (1991) 131;
(b) M. Lamrani, S. Gomez, F. Teixidor, C. Vinas, R. Sillanpaa, R.
Kiveas, Organometallics 16 (1997) 1278 (and references therein).
[6] I.B. Sivaev, A.A. Semioshkin, B. Brellochs, S. Sjoberg, V.I.
¨
Bregadze, Polyhedron 19 (2000) 627 (and references therein).
[7] P. Kasynski, D. Lipiak, K.A. Bairamov, E. Brady, M.K. Patel, J.
Laska, in: W. Siebert (Ed.), Advances in Boron Chemistry, The
Royal Society of Chemistry, Cambridge, 1997, p. 507.
[8] W.R. Hertler, M.S. Raasch, J. Am. Chem. Soc. 86 (1964) 3661.
[9] B. Gruner, B. Bonnetot, H. Mongeot, Collect. Czech. Chem.
¨
Acknowledgements
Commun. 62 (1997) 1185.
[10] T. Peymann, K. Klick, D. Gabel, Inorg. Chem. 36 (1997) 5139.
[11] D.D. Perrin, W.L. Armarego, D.R. Perrin, Purification of
Laboratory Chemicals, Pergamon Press, London, 1966.
Professor Jaromir Plesek from the Institute of Inor-
ganic Chemistry of the Academy of Sciences is acknowl-
edged for his discussions of the preparative aspects of
the ring cleavage reactions. This study is financially
supported by the European Commission in the frame-
work of the INCO-Copernicus program (Project IC15-
CT98-0221) and partly by Grant GACR No. 104/99/
1096 to B.G.
[12] (a) B. Gruner, Ph. D. Thesis, Czechoslovak Academy of Sciences,
¨
Prague, 1990.;
(b) G.R. Wellum, E.I. Tolpin, L.P. Andersen, R. Sneath, J.
Chromatogr. 103 (1975) 153.
[13] G. Simmonet, M. Oria, Les mesures de radioactivite´ a` l’aide des
compteurs a` scintillation liquide, Eyrolles, Paris, 1980.