Novel class of functionalized ionic liquids with grafted CMPO-moieties for actinides and rare-earth elements recovery

Article abstract of DOI:10.1039/b926377b

The general approach to a novel class of functionalized ionic liquids 4-6 bearing grafted diphenylcarbamoylmethylphosphine oxide complexing groups in the cation has been elaborated. The synthetic route comprises the preparation of the intermediate (diphenylphosphorylmethylcarbamoyl)propylimidazole 3, followed by sequential quaternization by alkyl halides (chlorides or bromides) and anionic exchange in the case of ionic liquids bearing the hexafluorophosphate anion. The structures of two ionic liquids were confirmed by X-ray analysis, revealing the strong intramolecular hydrogen bond formed by the acidic protons of the heterocycle and oxygen atom either of the PO or CO group, depending on the anion nature. In neutral media, these ionic ligands form complexes ML₂ with europium chloride or europium nitrate via an O,O-bidentate mode similar to known neutral CMPO compounds. The solid phase extractants prepared by immobilization of these FILs on solid matrixes possess sorption activity towards actinides and rare-earth elements in nitric acid solutions.

Full text of DOI:10.1039/b926377b

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PAPER
www.rsc.org/dalton | Dalton Transactions
Novel class of functionalized ionic liquids with grafted CMPO-moieties
for actinides and rare-earth elements recovery†
Irina L. Odinets,*a Elena V. Sharova,a Oleg I. Artyshin,a Konstantin A. Lyssenko,a Yulia V. Nelyubina,a
Galina V. Myasoedova,b Nadezhda P. Molochnikovab and Elena A. Zakharchenrob
Received 14th December 2009, Accepted 17th February 2010
First published as an Advance Article on the web 20th March 2010
DOI: 10.1039/b926377b
The general approach to a novel class of functionalized ionic liquids 4–6 bearing grafted
diphenylcarbamoylmethylphosphine oxide complexing groups in the cation has been
elaborated. The synthetic route comprises the preparation of the intermediate
(diphenylphosphorylmethylcarbamoyl)propylimidazole 3, followed by sequential quaternization by
alkyl halides (chlorides or bromides) and anionic exchange in the case of ionic liquids bearing the
hexafluorophosphate anion. The structures of two ionic liquids were confirmed by X-ray analysis,
revealing the strong intramolecular hydrogen bond formed by the acidic protons of the heterocycle and
=
=
oxygen atom either of the P O or C O group, depending on the anion nature. In neutral media, these
ionic ligands form complexes ML2 with europium chloride or europium nitrate via an O,O-bidentate
mode similar to known neutral CMPO compounds. The solid phase extractants prepared by
immobilization of these FILs on solid matrixes possess sorption activity towards actinides and
rare-earth elements in nitric acid solutions.
systems. Moreover, the coordination environment of the metal ions
Introduction
in ionic liquids can differ from what is observed in other organic
solvents.6 Over the extraction, cationic or anionic metal species
become part of the ionic liquid itself, while the original liquid is
destroyed. It should be noted that, as many ionic liquids contain
weakly coordinating anions, it will, in general, not be possible
to extract metal ions from an aqueous phase to the ionic liquid
phase in the absence of extractants.6 Among the typical extractants
for the processing of accumulated liquid acidic radioactive wastes,
bidentate carbamoylmethylphosphine oxides (CMPO), e.g., (N,N-
diisobutylcarbamoylmethyl)octylphenylphosphine oxide 1a9 or
N,N-dibutylcarbamoylmethyldiphenylphosphine oxide 1b,10 are
known to be preferable from cost and effectiveness of extraction
points of view. It was demonstrated that CMPO dissolved in
[bmim]PF6 can extract lanthanide nitrates from deionized water,
and the presence of ionic liquid improved the extractability as well
the selectivity of CMPO.11
Ionic liquids (ILs) are extensively studied nowadays, and have
found applications in catalysis,1 analytical chemistry,2 and as
promoting and recyclable reaction media in different synthetic
procedures.3 The critical review of Seddon and Plechkova demon-
strated the parallel and collaborative exchanges between research
and industrial developments, dealing both with nitrogen and
phosphonium ionic liquids.4 Notably, hydrophobic ionic liquids
themselves have been considered as an alternative for the organic
phase in liquid–liquid solvent extraction systems, e.g., for the
separation of f -elements.5–7 Indeed, the imidazolium ionic liquids
are relatively radiation resistant and do not undergo significant
decomposition by radiolysis upon exposure to high radiation
doses.8 In this context, it should be taken into account that due
to the ionic nature of ILs, the partitioning equilibria in solvent
extraction systems involving ionic liquids are not necessarily
identical to those involving conventional organic solvents. The
equilibria often involve cation or anion exchange between the
aqueous phase and the ionic liquid phase, and the contamination
of the aqueous phase by the components of the ionic liquid is a
problem for the applicability of ionic liquids in solvent extraction
Recently, the development of functionalized ionic liquids (FILs)
(also referred to as task-specific ionic liquids (TSILs)) have
received much attention due to their potential to impart on the
liquid specific chemical and/or physical properties.12 Therefore,
new ILs are being introduced in which a functional group is
incorporated as a part of the cation or anion structure. These
functional groups can impart a particular reactivity pattern to
the IL, enhancing its capacity for interaction with specific solute
types. There have been recent developments in functionalized
imidazolium salts, which can be used for specific tasks ranging
from catalyst recycling, supports for organic synthesis, catalysis,
separation of specific metal ions from aqueous solution, and
aA. N. Nesmeyanov Institute of Organoelement Compounds, Russian
Academy of Sciences, Vavilova str. 28, 119991 Moscow, Russia.
E-mail: odinets@ineos.ac.ru
bInstitute of Geochemistry and Analytical Chemistry, Russian Academy of
Sciences, Kosygina str. 19, 119991, Moscow, Russian Federation
† Electronic supplementary information (ESI) available: The synthetic
procedures and characterization of the precursor 3, 31P NMR spectra
for ligands 4a–f, 5c–f, 6a–f, 19F NMR spectra for ligands 6a–f with
PF6 anion, the principal bond distances and angles in the structures of
ligands 4d and 6c, and tables with complete data collection parameters
for these structures. CCDC reference numbers 758107 and 758108. For
ESI and crystallographic data in CIF or other electronic format see DOI:
10.1039/b926377b
4170 | Dalton Trans., 2010, 39, 4170–4178
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construction of nanostructures and ion-conductive materials.12
For example, ILs with thioether, thiourea, and urea functional
groups capable of complexation and incorporated in the alkyl
chains of the imidazolium cations have been prepared and used,
-
in combination with the PF6 anion, alone or in a mixture
with [C4mim][PF6], for Hg2+ and Cd2+ extraction in liquid–
liquid separations.13 Furthermore, the salicylaldehyde-derived
imidazolium salts were suggested to extract Ni2+ ions from aque-
ous solutions,14 and those with phosphoramide-functionalized
imidazolium14 or ammonium cations7c for recovery of actinides
from aqueous solutions.
Scheme 1 Synthesis of CMPO-modified ionic liquids 4–6.
The extractant molecules serve to dehydrate the metal ions and
offer a more hydrophobic environment that enables their transport
to the extracting phase. Attaching a metal ion coordinating group
directly to the imidazolium cation makes the extractant an integral
part of the hydrophobic phase and greatly diminishes the chance
of loss to the aqueous phase. That prompts the investigation of
the functionalized ionic liquid concept for metal ion extraction in
ILs.
Upon grafting of such bidentate complexing substructures onto
the organic cation of RTILs, the resulting FILs could combine
the useful properties both of the IL and the extracting agent,
suppressing the problems encountered through extractant/solvent
miscibility and facilitating actinide recovery. Thus, Ouadi and co-
workers designed task-specific ionic liquids 2 for the extraction of
trivalent americium, which contained the 2-hydroxybenzylamine
moiety attached to the 1-butylimidazolium core and either
hexafluorophosphate (PF6) or bis(trifluoromethylsulfonyl)imide
(Tf2N) counteranions.15 These ionic liquids act as extractants and
were used in pure form or diluted in another ionic liquid for the
extraction of americium from the aqueous to the ionic liquid phase
under basic conditions. Americium could be stripped from the
ionic liquid phase by washing with an acidic aqueous solution.
amidation of diphenylphosphorylacetic acid ethyl ester with 3-
aminopropylimidazole in ethanol solution according the proce-
dure reported by us recently.16
Compounds 4–6 were isolated as off-white hygroscopic solids
◦
with melting points mostly in the range of 57–129 C, excluding
compounds 4c, 5c, and 6c (R = Hex) which possessed the highest
melting points in the range of 154–161 ◦C. The structures of
the intermediate imidazole 3 as well as ionic liquids 4–6 were
unambiguously confirmed by the multinuclear NMR data and
elemental analysis data. The IR spectra of all compounds (KBr
pellets or nujol for 6a–f bearing the weakly coordinating PF6
anion) show characteristic absorption bands at 1649–1664 cm-1
-1
=
=
(C O) and 1163–1197 cm (P O). Usually, the band character-
=
istic to the P O group has two maxima, suggesting the partial
=
formation of a hydrogen bond P O ◊ ◊ ◊ H. The absorption of the
NH group appears as a broad band at 3159–3256 cm-1 (NH
stretching vibrations) and bands at 1550–1591 cm-1 (combined
frequencies of NH bending vibrations and C–N vibrations). The
CH2 bending vibrations are observed at 1437–1468 cm-1. The 31
P
NMR spectra show singlets at ca. 30 ppm, i.e., these signals appear
in the region characteristic of this type of environment of the
phosphorus atom.9,10,16 The 1H NMR spectra are consistent with
the structures of the resulting compounds and have, along with
characteristic signals for the hydrogen atoms in the substituents at
the phosphorus and heterocyclic nitrogen atom, the characteristic
doublet for the protons of the PCH2 group at 3.45–3.90, with
the spin–spin coupling constant of 12.8–13.7 Hz. It should be
noted that the signal assigned to the acidic CH-proton of the
imidazolium ring located at 10.05–10.35 ppm for ionic liquids
4a–f and 5c–f with halide anions was upfield shifted to 8.81–
9.18 ppm for their analogues 6a–f bearing the hexafluorophos-
phate anion. The presence of only one singlet characteristic for the
proton of the N–CH–N moiety in the 1H NMR spectra of ligands
6a–f along with the elemental analysis data provided evidence that
these ILs are free from halide impurities. Similarly, the 13C NMR
spectra fit well the depicted structures.
In this paper, we report on the synthesis and characterization
of a novel type of imidazolium FILs bearing CMPO moieties in
alkyl chain, along with their application as active agents for solid
phase extractants’ preparation for the recovery of actinides and
rare earth elements from nitric acid solutions.
Results and discussion
Synthesis of CMPO-modified ionic liquids
The general approach to the synthesis of the desired FILs is based
on the quaternization of (phosphorylmethylcarbamoyl)propyl-
substituted imidazole 3 by different alkyl halides, namely bromides
or chlorides. The alkylation performed in acetonitrile solution
presents a rather sluggish reaction; however, the final compounds
were obtained as white crystalline compounds in high yields
and in high purity after a simple work-up (see experimental).
The subsequent anion exchange reaction under the treatment
with sodium hexafluorophosphate afforded the FILs with the
hexafluorophosphate anion (Scheme 1). The starting CMPO-
functionalized imidazole 3 was, in turn, obtained via the direct
To obtain additional data on the structure of these CMPO-
modified ILs, the molecular structures of bromide 4d and hexafluo-
rophosphate 6c were established by X-ray diffraction. The general
views of these compounds (with solvated molecules excluded) are
shown in Fig. 1 and 2, respectively. Selected bond lengths and
angles are given in Table S1 in the ESI.† In general, the presence of
the more elongated octyl group at the heterocyclic nitrogen atom
and the bromine anion in 4d lead to a molecular conformation
and cation–anion interactions that are totally different compared
with those in 6c bearing the PF6 anion. Thus, in crystal structure
6c, the acidic proton H(2A) in the heterocycle binds to the
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◦
˚
parameters are: C ◊ ◊ ◊ F◦3.511(4) A, CHF 163(1) and C ◊ ◊ ◊ O
˚
3.208(5) A, CHO 139(1) .
In the crystal of 4d, the amide group binds to the bromide anion
◦
˚
(N ◊ ◊ ◊ Br 3.349(3) A, NHBr 156(1) ), which is a more effective
proton acceptor. Therefo◦ re, the C(2)–H(2A) ◊ ◊ ◊ O bond (C ◊ ◊ ◊ O
˚
3.127(4) A, CHO 154(1) ) is formed with the phosphoryl moiety.
The protons H(4A) and H(5A) of the heterocycle interact with the
◦
˚
carbonyl group (C ◊ ◊ ◊ O 3.109(4) A, CHO 162(1) ) and bromine
◦
˚
anion (C ◊ ◊ ◊ Br 3.693(3) A, CHBr 149(1) ), respectively.
As a result, the counteranion causes the marked difference
in intermolecular and intramolecular binding in these CMPO-
modified ILs that is responsible for stabilizing different molecular
conformations.
In model experiments, using compound 4c as a representative
example, we demonstrated that the CMPO-modified ionic ligands
readily form stable complexes of ML2 composition with europium
trichloride and europium nitrate in neutral medium (ethanolic
solutions) (Scheme 2).
Fig. 1 General view of 4d.
Scheme 2 Synthesis of europium complexes 7a,b.
The considerable upfield shift of the signals of europium
complexes 7a,b in the 31P NMR spectra compared to the signal of
the free ligand 4c provide convincing evidence for the participation
of the phosphine oxide group in the coordination. The IR
spectra of solid-state complexes 7a,b exhibit no absorption bands
=
=
characteristic of the free P O and C O groups. Instead, the
spectrum contains bands at 1161 (7a) and 1162 cm-1 (coordinated
-1
=
=
P O group) and at 1628 and 1629 cm (coordinated C O group).
In complex 7b, the nitrate groups coordinated in a bidentate
-1
=
manner absorb at 1470 (n(N O)), 1317 (nas(NO2)), and 1031 cm
(ns(NO2)). The absence of the absorption band at ~1380 cm-1 (free
nitrate group) suggests that all of the nitrate groups in complexes
7b are coordinated by the metal in a bidentate fashion. These data
allow one to assume that the CMPO-modified ionic ligands under
investigation act as O,O-bidentate ligands towards f -elements,
similar to known neutral CMPO ligands.18
Fig. 2 General view of 6c.
◦
˚
hexafluorophosphate moiety (C ◊ ◊ ◊ F 3.238(4) A, CHF 168(1) ),
as is typical in the case for most ILs.17 In bromine salt 4d, this
hydrogen atom does not interact with the anion. In contrast, it
forms a strong intramolecular hydrogen bond with the oxygen
atom of the phosphoryl group. The reasons for this difference in
proton acceptors are as follows.
Application of CMPO-modified ionic liquids for the preparation of
solid phase extractants
It seems reasonable to estimate the possibility of using these
FILs for the extraction of f -elements. However, the highest
extent of trivalent actinide separation from nitric acid media is
achieved using high concentrations of CMPO in organic phase,
while the sorption procedures using solid extractants prepared
by non-covalent fixing of such ligands on different matrixes are
more effective for recovery of trivalent actinides.19 Moreover, the
possibilities of ionic liquids to be kept on solid surfaces and
to possess ion exchange and complexing properties give them
potential for the preparation of solid phase extractants. Thus,
When the IL cations are isolated from the surroundings,
hydrogen bonds are most likely to occur between the NH
and PO groups. Indeed, in IL 6c, the expected intramolecular
◦
˚
=
N–H ◊ ◊ ◊ O P bond (N ◊ ◊ ◊ O 2.876(5) A, NHO 164(1) ) is ob-
=
served. As the C O group and the rest of the hydrogen atoms of
imidazole are second in line, there is a weaker C(4)–H(4A) ◊ ◊ ◊ F in-
teraction with the PF6- anion and an additional C(5)–H(5A) ◊ ◊ ◊ O
bond with the carboxyl group. The corresponding geometrical
4172 | Dalton Trans., 2010, 39, 4170–4178
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previously we demonstrated the possibility to fix phosphonium-
type ionic liquids in a mixture with CMPO ligand 1b on the
polyacrylonitrile (PAN) fiber, and solid phase extractants prepared
in this way were successfully used for actinides recovery from nitric
and hydrochloric acid solutions.20
It should be mentioned that ionic liquids with the hexaflu-
orophosphate anion are believed to be unstable to hydrolysis,
especially in acidic media. Using the compound 6c with R =
Hex as a representative example, in a special experiment we
estimated its hydrolytic stability in 3 M nitric acid. After 2 h
of intensive stirring, i.e., the period of time used in sorption
experiments, acetonitrile was added to the two-phase system
for the formation of a clear solution. The 31P NMR spectrum
of the sample did not reveal formation of fluorophosphate or
phosphate anions, and no presence of HF was observed in
the corresponding 19F spectrum. These data indicate relatively
high hydrolytic stability of the reported FILs with the [PF6]
anion.
Although complexes obtained in model experiments in neutral
media often differ from complexes produced in an organic
phase during real extraction or sorption from acidic media, the
fact that CMPO-modified ionic liquids form complexes with f -
elements similar to other CMPO ligands, i.e., via O,O-bidentate
chelate mode, allows us to suggest that the mechanism of
sorption comprises the formation of complexes of such type,
in which nitrate anions may be included into the coordina-
tion sphere of the metal. The difference in trivalent actinides’
sorption depending on the solid support in use is apparently
connected with the mode of bonding of these ionic ligands on
the surface of the matrix, and extraction conditions as well. In
other words, non-covalent fixing of a ligand on the surface of
hydrophilic matrixes, realized through the hydrophilic NH-groups,
may prevent effective complexation with metal cations, while on
the surface of hydrophobic carbon nanotubes the ligand may
be bound via the hydrophobic imidazolium moiety giving, in
turn, better possibilities for bidentate complexation typical for
CMPO-ligands.
In the present study for the preparation of sorbents, we used
R
PAN fiber, acrylate resin Amberlit XAD-7ꢀ, hyper-cross-linked
R
polystyrene and multi-walled carbon nanotubes (Taunitꢀ) as solid
supports. For the preparation of sorbents, these solid matrixes were
treated with solutions of FILs in dichloroethane or ethanol (on
the basis of 0.003 mmol g-1) followed by air drying. As the most
selective preconcentration of lanthanides and actinides is usually
performed from high acid solutions, in which they exist as anionic
complexes, in the experiments model nitric acid solutions (3 M
HNO3) of Pu(IV) and Eu(III) were used.
The nature of the cation (the length of the alkyl group R) and
anion in the FILs 4–6, as well as the type of solid support, were
found to be important for effective sorption of metal cations.
The sorbents on the base of hydrophilic polyacrilonitrile fiber and
other hydrophilic matrixes were effective for plutonium recovery
from nitric acid solutions (3 M HNO3) (Table 1). The sorbents
prepared using FILs 4c and 5c with short hexyl radicals and halide
anions were less effective compared to that based on FIL 6c having
the same cation but the hydrophobic hexafluorophosphate anion.
Vice versa, among the sorbents impregnated by FILs 4d, 5d or
6d, with octyl group R at the nitrogen atom, the effectiveness of
sorption decreased in the series Cl > Br > PF6, while in the case of
sorbents impregnated by ionic liquids 4f, 5f or 6f with the longest
hexadecyl group, the anion nature did not significantly influence
the recovery extent (91, 92 and 94%, respectively). However, under
other conditions being equal, the same sorbents were unsuitable
for Eu(III) recovery (11–74%), and in this case, the sorbents
impregnated with chlorides 5d and 5f provided better results (74
and 58%, respectively).
These preliminary experiments have shown that a novel class of
functionalized ILs with grafted CMPO-moieties possess promis-
ing properties for actinide and rare-earth elements recovery from
acidic solutions. In this paper, we only outlined the prospects of
this area and our further study will comprise investigation of the
acid nature influence and that of pH of an aqueous phase on the
effectiveness of sorption along with estimation of the reversibility
of metal sorption.
At the same time, the sorbent based on hydrophobic multi-
R
walled carbon nanotubes (Tauniteꢀ) in combination with hy-
drophobic FIL 6f with the hexafluorophosphate anion resulted
in 97% recovery of Pu(IV) and a drastic increase of recovery for
trivalent actinides (87 and 89% recovery of Eu(III) and Am(III),
respectively) from nitric acid solutions (3 M HNO3), with excellent
sorption properties towards U(VI) (99% recovery) as well. Table 1
summarizes the results presented.
Conclusion
Table 1 Extraction degree (%) of Pu(IV) and Eu(III) by “solid-phase
extractants” on the base of PAN-fiber and carbon nanotubes. 3 M HNO3;
content of reagent 0.003 mM g-1, 2 h, V : m = 100 : 1; 2h
In conclusion, we have reported an efficient way to synthesize a
new class of FILs bearing a bidentate CMPO complexing moiety
in the pendant arm of the cation. The preliminary results described
here show that high separation of Pu(IV), Am(III), Eu(III), and
U(VI) can be achieved using these ILs as active agents of solid
phase sorbents based on carbon nanotubes. The nanostructure
features and large surface of the carbon nanotubes determine their
high sorption ability and further wide possibilities for creation
of solid phase extractants on their base. Ionic liquids possess
negligible flammability and volatility and, therefore, represent a
new class of ‘‘green’’ solvents. In this sense, further studies will
include further improvements of the structure and detailed inves-
tigation of the influence of its nature on sorption and extraction
properties.
Run Cmpd Matrix
R
Anion Pu(IV) Eu(III)
1
2
3
4
5
6
7
8
5c
4c
6c
5d
4d
6d
5f
4f
6f
6f
PAN-fiber
PAN-fiber
PAN-fiber
PAN-fiber
PAN-fiber
PAN-fiber
PAN-fiber
PAN-fiber
PAN-fiber
carbon nanotubes
C6H13 Cl
C6H13 Br
C6H13 PF6
C8H17 Cl
C8H17 Br
C8H17 PF6
C16H33 Cl
C16H33 Br
C16H33 PF6
C16H33 PF6
60
62
87
95
83
79
92
91
94
97
11
22
20
74
10
21
58
11
33
87
9
10a
a Sorption of U(IV): 99%, Am(III): 89%
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=
(br. s, 1H, NH); 10.14 (br. s, 1H, N CH–N). IR (KBr): 510 (w),
525 (m), 732 (m), 1120 (w), 1166 & 1186 (s, nP=O), 1308 (br, w),
Experimental
Materials and methods
1437 (m, nCH ), 1559 (s, nNH), 1664 (s, nC=O), 2987 (m), 3054 (s),
2
3238 (m) cm-1. Anal. calcd for C24H31BrN3O2P·1H2O: C, 55.18; H,
The NMR spectra were recorded on a Bruker AMX-300 and a
Bruker AMX-400 instruments in CDCl3 and DMSO-d6 solutions.
The chemical shifts (d) were internally referenced by the residual
solvent signals relative to tetramethylsilane (1H and 13C) or
externally to H3PO4 (31P). The 19F chemical shifts were determined
with CFCl3 as an external standard. The 13C NMR spectra were
registered using the JMODECHO mode; the signals for the C
atoms bearing odd and even numbers of protons have opposite
polarities. IR spectra were recorded on a Magna-IR 750 FTIR-
spectrometer (Nicolet Co., resolution 2 cm-1, scan number 128,
KBr pellets or nujol). Melting points were determined with an
Electrothermal IA9100 Digital Melting Point Apparatus and were
uncorrected.
6.37; N, 8.04. Found: C, 55.11; H, 6.21; N, 8.07.
1-[3-[[(Diphenylphosphinyl)acetyl]amino]propyl]-3-hexyl-1H -
imidazol-3-ium bromide (4c). Yield: 81%. M.p. 157-158 ◦C.
31P NMR (162 MHz, CDCl3): d 30.80. 1H NMR (400 MHz,
3
CDCl3): 0.85 (t, 3H, CH3(CH2)4CH2–N, JH–H = 6.8 Hz); 1.24-
1.28 (m, 6H, CH3(CH2)3CH2CH2–N); 1.85 (appeared quintet,
3
2H, CH2CH2NHC(O), JH–H = 6.5 Hz); 2.06 (appeared quintet,
3
2H, CH3(CH2)3CH2CH2–N, JH–H = 6.0 Hz); 3.08 (appeared q,
2H, CH2NHC(O),3JH–H = 5.8 Hz); 3.71 (d, 2H, PCH2, JP–H
=
2
3
13.0 Hz); 4.19 (t, 2H, CH2CH2CH2NHC(O), JH–H = 7.8 Hz);
4.28 (t, 2H, CH3(CH2)4CH2–N, 3JH–H = 6.3 Hz); 7.21 (t, 1H, C5H
in Im, 3JH–H = 1.7 Hz); 7.42-7.52 (m, 6H, m-, p-H in C6H5P); 7.70
(t, 1H, C4H in Im, 3JH–H = 1.8 Hz); 7.82-7.88 (m, 4H, O–H C6H5P);
Diphenylphosphoryl acetic acid was obtained via the known
procedure,21 other reagents were used without further purification
as purchased (Acros). For full details concerning the synthetic
procedures and characterization of the precursor 3, see the ESI.†
8.79 (br. t, 1H, NH, 3JH–H = 4.8 Hz); 10.11 (br. s, 1H, N CH–N).
=
IR (KBr): 509 (m), 522 (m), 1166 & 1184 (s, nP=O), 1440 (m, nCH2 ),
1551 & 1566 (nNH), 1650 (s, nC=O), 2933 (s), 3070 (s), 3088 (s), 3208
(m) cm-1. Anal. calcd for C26H35BrN3O2P: C, 58.65; H, 6.63; N,
7.89; P, 5.82. Found: C, 58.47; H, 6.61; N, 7.91; P, 5.81.
1-[3-[[(Diphenylphosphinyl)acetyl]amino]propyl]-3-alkyl-1H-
imidazol-3-ium bromides 4a–f (general procedure)
1-[3-[[(Diphenylphosphinyl)acetyl]amino]propyl]-3-octyl-1H -
◦
imidazol-3-ium bromide (4d). Yield: 84%. M.p. 100-101 C. 31P
To a solution of 3-(1H-imidazol-1-yl)-1-propanamine 3 (1 equiv.)
in anhydrous CH3CN (10 mL), the corresponding alkyl bromide
(1.2 equiv.) was added dropwise at 0 ◦C under argon. The mixture
was stirred at r.t. for 12 h followed by stirring at 80–85 ◦C for 70 h.
Then the solvent was evaporated under vacuum and the resulting
solid residue was washed with Et2O (2 ¥ 10 mL). The residual
ether was removed under reduced pressure and the solid residue
was dried under vacuum (2 mm Hg) at 55 ◦C for 7 h.
NMR (121.5 MHz, CDCl3): d 31.21. 1H NMR (300 MHz,
3
CDCl3): d 0.85 (t, 3H, CH3(CH2)6CH2–N, JH–H = 6.9 Hz);
1.19-1.38 (m, 10H, CH3(CH2)5CH2CH2–N); 1.74-1.92 (m, 2H,
CH2CH2NHC(O)); 2.01-2.13 (m, 2H, CH3(CH2)5CH2CH2–N);
3.09 (appeared q, 2H, CH2NHC(O),3JH–H = 5.1 Hz); 3.72 (d,
2H, PCH2, 2JP–H = 13.0 Hz); 4.19 (t, 2H, CH2CH2CH2NHC(O),
3JH–H = 7.6 Hz); 4.29 (t, 2H, CH3(CH2)6CH2–N, 3JH–H = 6.4 Hz);
7.20 (br. s, 1H, C5H in Im); 7.43-7.53 (m, 6H, m-, p-C6H5P); 7.68
(br. s, 1H, C4H in Im); 7.82-7.89 (m, 4H, O–H in C6H5P); 8.80
1-[3-[[(Diphenylphosphinyl)acetyl]amino]propyl]-3-ethyl-1H -
imidazol-3-ium bromide (4a). Yield: 76%. M.p. 85-87 ◦C. 31P
NMR (121.5 MHz, CDCl3): d 33.99. 1H NMR (300 MHz, CDCl3):
d 1.60 (t, 3H, CH3CH2–N, 3JH–H = 7.3 Hz); 2.11 (appeared quintet,
(br. t, 1H, NH, 3JH–H = 5.4 Hz); 10.12 (br. s, 1H, N CH–N). 13C
=
NMR (75.47 MHz, CDCl3): d 13.46 (CH3), 21.93, 25.83, 28.28,
28.39, 28.89, and 29.54 (six s, CH2 in octyl), 31.03 (CH2CH2N),
3
1
2H, CH2CH2NHC(O), JH–H = 5.4 Hz); 3.14 (appeared q, 2H,
34.39 (NHCH2), 39.80 (d, PCH2, JPC = 65.3 Hz), 45.77 (NIm–
CH2NHC(O),3JH–H = 5.3 Hz); 3.90 (d, 2H, PCH2, 2JP–H = 13.0 Hz);
4.29-4.39 (m, 4H, CH2CH2CH2NHC(O)+CH3CH2-N); 7.36 (br. s,
1H, C5H in Im); 7.51-7.62 (m, 6H, m-, p-H in C6H5P); 7.84 (br. s,
1H, C4H in Im); 7.91-7.98 (m, 4H, O-H in C6H5P); 8.98 (br. t, 1H,
CH2), 49.43 (NIm–CH2), 121.57 (C4(Im)), 122.40 (C5(Im)), 128.10
(d, m-C in C6H5, 3JPC = 12.1 Hz), 130.53 (d, o-C in C6H5, 2JPC
=
1
9.9 Hz), 131.45 (p-C in C6H5), 131.66 (d, ipso-C in C6H5, JPC
=
103.2 Hz), 136.46 (C2(Im)), 165.12 (d, C(O), JPC = 5.5 Hz). IR
(KBr): 513 (w), 521 (w), 701 (w), 727 (m), 747 (m), 1120 (m),
1166 & 1187 (s, nP=O), 1308 (br), 1437 (m, nCH2 ), 1553 & 1564 (s,
2
NH, 3JH–H = 5.9 Hz); 10.17 (br. s, 1H, N CH–N). IR (KBr): 509
=
(m), 523 (m), 696 (w), 730 (m), 1120 (w), 1164 & 1185 (s, nP=O),
1308 (w), 1437 (m, nCH ), 1555 (s, nNH), 1663 (s, nC=O), 2985 (m),
n
n
NH), 1649 (s, nC=O), 2855 (s), 2929 (s), 3054 (s), 3138 (s), 3208 (m,
2
3053(s), 3233 (m) cm-1. Anal. calcd for C22H27BrN3O2P·2H2O: C,
NH) cm-1. Anal. calcd for C28H39BrN3O2P· /3CHCl3: C, 56.69; H,
1
51.57; H, 6.10; N, 8.20. Found: C, 51.14; H, 5.41; N, 8.21.
6.60; N, 7.00; P, 5.16. Found: C, 56.85; H, 6.91; N, 7.21; P, 4.80.
1-[3-[[(Diphenylphosphinyl)acetyl]amino]propyl]-3-butyl-1H -
imidazol-3-ium bromide (4b). Yield: 93%. M.p. 79-81 ◦C. 31P
NMR (121.5 MHz, CDCl3): d 34.14. 1H NMR (300 MHz,
1-[3-[[(Diphenylphosphinyl)acetyl]amino]propyl]-3-tetradecyl-
◦
1H-imidazol-3-ium bromide (4e). Yield: 94%. Mp 72-73 C. 31P
NMR (121.5 MHz, CDCl3): d 30.37. 1H NMR (300 MHz, CDCl3):
3
3
CDCl3): d 0.95 (t, 3H, CH3(CH2)2CH2–N, JH–H = 7.1 Hz); 1.35
d 0.84 (t, 3H, CH3(CH2)12CH2–N, JH–H = 6.9 Hz); 1.18-1.29
(sextet, 2H, CH3CH2CH2CH2–N, 3JH–H = 7.1 Hz); 1.87 (appeared
quintet, 2H, CH2CH2NHC(O), 3JH–H = 7.1 Hz); 1.99-2.18 (m, 2H,
CH3CH2CH2CH2–N); 3.02-3.21 (m, 2H, CH2NHC(O)); 3.81 (d,
2H, PCH2, 2JP–H = 13.2 Hz); 4.23 (t, 2H, CH2CH2CH2NHC(O),
3JH–H = 7.1 Hz); 4.30 (t, 2H, CH3(CH2)2CH2–N, 3JH–H=5.9); 7.24
(br. s, 1H, C5H in Im); 7.42-7.58 (m, 6H, m-, p-H in C6H5P); 7.77
(br.s, 1H, C4H in Im); 7.86-7.93 (m, 4H, O-H in C6H5P); 8.90
(m, 22H, CH3(CH2)11CH2CH2–N); 1.82 (appeared quintet, 2H,
3
CH2CH2NHC(O), JH–H = 5.9 Hz); 2.04 (appeared quintet, 2H,
3
CH3(CH2)11CH2CH2–N, JH–H = 5.4 Hz); 3.07 (appeared q, 2H,
CH2NHC(O),3JH–H = 6.5 Hz); 3.69 (d, 2H, PCH2, 2JP–H = 13.1 Hz);
3
4.16 (t, 2H, CH2CH2CH2NHC(O), JH–H = 7.7 Hz); 4.26 (t, 2H,
CH3(CH2)12CH2–N, 3JH–H = 6.1 Hz); 7.23 (br. s, 1H, C5H in Im);
7.40-7.48 (m, 6H, m-, p-H in C6H5P); 7.75 (br. s, 1H, C4H in Im);
4174 | Dalton Trans., 2010, 39, 4170–4178
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3
3
7.80-7.87 (m, 4H, O–H in C6H5P); 8.77 (br. t, 1H, NH, JH–H
=
d 0.91 (t, 3H, CH3(CH2)6CH2–N, JH–H = 6.9 Hz); 1.26-1.39
=
5.6 Hz); 10.05 (br. s, 1H, N CH–N). IR (KBr): 509 (m), 523 (m),
695 (m), 728 (m), 745 (m), 1120 (w), 1166 & 1188 (s, nP=O), 1308
(m, 10H, CH3(CH2)5CH2CH2–N); 1.90 (appeared quintet, 2H,
3
CH2CH2NHC(O), JH–H = 6.8 Hz); 2.10 (appeared quintet, 2H,
3
(br), 1437 (m, nCH ), 1561 (s, nNH), 1664 (s, nC=O), 2853 (m), 2924
CH3(CH2)5CH2CH2–N, JH–H = 4.8 Hz); 3.13 (appeared q, 2H,
2
(s), 3055 (s), 3235 (m, nNH) cm-1. Anal. calcd for C34H51BrN3O2P:
C, 63.35; H, 7.97; N, 6.52; P, 4.80. Found: C, 63.17; H, 8.07; N,
6.49; P, 4.61.
CH2NHC(O),3JH–H = 5.5 Hz); 3.77 (d, 2H, PCH2, 2JP–H = 13.2 Hz);
3
4.26 (t, 2H, CH2CH2CH2NHC(O), JH–H = 7.8 Hz); 4.36 (t, 2H,
CH3(CH2)6CH2–N, 3JH–H = 6.2 Hz); 7.24 (br. s, 1H, C5H in Im);
7.51-7.61 (m, 6H, m-, p-H in C6H5P); 7.69 (br. s, 1H, C4H in Im);
7.88-7.95 (m, 4H, O–H in C6H5P); 9.35 (br. s, 1H, NH); 10.33
1-[3-[[(Diphenylphosphinyl)acetyl]amino]propyl]-3-hexadecyl-
◦
1H-imidazol-3-ium bromide (4f). Yield: 87%. Mp 67-68 C. 31P
=
(br. s, 1H, N CH–N). IR (KBr): 510 (m), 523 (m), 696 (m), 729
(m), 747 (m), 1120 (m), 1163 & 1189 (s, nP=O), 1309 (m, br), 1437
NMR (162 MHz, CDCl3): d 30.92. 1H NMR (400 MHz, CDCl3):
3
d 0.86 (t, 3H, CH3(CH2)14CH2–N, JH–H = 7.0 Hz); 1.17-1.33
(m, nCH ), 1560 (s, nNH), 1663 (s, nC=O), 2855 (s), 2927 (s), 2923 (s),
2
(m, 26H, CH3(CH2)13CH2CH2–N); 1.85 (appeared quintet, 2H,
3054 (s), 3235 (br, nNH) cm-1. Anal. calcd for C28H39ClN3O2P: C,
65.17; H, 7.62; N, 8.14; P, 6.00. Found: C, 64.71; H, 7.95; N, 8.14;
P, 5.90.
3
CH2CH2NHC(O), JH–H = 5.2 Hz); 2.08 (appeared quintet, 2H,
3
CH3(CH2)13CH2CH2–N, JH–H = 5.3 Hz); 3.10 (appeared q, 2H,
CH2NHC(O),3JH–H = 5.3 Hz); 3.71 (d, 2H, PCH2, 2JP–H = 12.9 Hz);
3
4.19 (t, 2H, CH2CH2CH2NHC(O), JH–H = 7.5 Hz); 4.30 (t, 2H,
1-[3-[[(Diphenylphosphinyl)acetyl]amino]propyl]-3-tetradecyl-
CH3(CH2)14CH2–N, 3JH–H = 6.6 Hz); 7.18 (br. s, 1H, C5H in Im);
7.45-7.52 (m, 6H, m-, p-H in C6H5P); 7.65 (br. s, 1H, C4H in Im);
7.83-7.88 (m, 4H, O–C6H5P); 8.80 (br. s, 1H, NH); 10.15 (br. s,
1H-imidazol-3-ium chloride (5e). Yield: 87%. highly hygroscopic
material. 31P NMR (121.5 MHz, CDCl3): d 30.36. 1H NMR
3
(300 MHz, CDCl3): d 0.91 (t, 3H, CH3(CH2)12CH2–N, JH–H
6.4 Hz); 1.19-1.39 (m, 22H, CH3(CH2)11CH2CH2–N); 1.88 (ap-
=
=
1H, N CH–N). IR (KBr): 509 (m), 523 (m), 695 (m), 728 (m),
3
1120 (w), 1166 & 1187 (s, nP=O), 1308 (br), 1437 (s, nCH2 ), 1466 (s),
1561 (s, nNH), 1664 (s, nC=O), 2851 (m), 2923 (s), 3053 (s), 3235 (m,
peared quintet, 2H, CH2CH2NHC(O), JH–H = 6.3 Hz); 2.06
(appeared quintet, 2H, CH3(CH2)11CH2CH2–N, 3JH–H = 5.3 Hz);
3.10 (appeared q, 2H, CH2NHC(O),3JH–H = 4.8 Hz); 3.76 (d,
2H, PCH2, 2JP–H = 13.0 Hz); 4.22 (t, 2H, CH2CH2CH2NHC(O),
3JH–H = 7.5 Hz); 4.33 (t, 2H, CH3(CH2)12CH2–N, 3JH–H = 5.9 Hz);
7.29 (br. s, 1H, C5H in Im); 7.46-7.56 (m, 6H, m-, p-H in C6H5P);
7.81 (br. s, 1H, C4H in Im); 7.88-7.94 (m, 4H, O–H in C6H5P);
n
NH) cm-1. Anal. calcd for C36H55BrN3O2P: C, 64.27; H, 8.24; N,
6.25; P, 4.60. Found: C, 64.31; H, 8.29; N, 6.11; P, 4.36.
1-[3-[[(Diphenylphosphinyl)acetyl]amino]propyl]-3-alkyl-1H-
imidazol-3-ium chlorides (5c–f)
9.33 (br. t, 1H, NH, 3JH–H = 5.0 Hz); 10.25 (br. s, 1H, N CH–N).
=
A mixture of 3-(1H-imidazol-1-yl)-1-propanamine 3 (3.3 mmol)
and the corresponding alkyl chloride (3.9 mmol) in 8 mL of
anhydrous CH3CN was heated in a sealed tube on a boiling water
bath for 160–170 h. The tube was opened and the solvent was
removed in vacuo. The crude product was washed with a mixture
of Et2O–EtOH (10 : 1, 2 ¥ 10 mL) and the residual solvent was
removed in vacuo. Additional Et2O (30 mL) was added to the
IR (KBr): 509 (m), 524 (m), 696 (m), 729 (m), 746 (m), 1121 (m),
1167 & 1186 (s, nP=O), 1310 (m, br), 1437 & 1466 (m, nCH2 ), 1562 (s,
n
NH), 1664 (s, nC=O), 2853 (s), 2924 (s), 3056 (s), 3245 (m, nNH), 3412
(br, H2O) cm-1. Anal. calcd for C34H51ClN3O2P·1H2O: C, 66.05;
H, 8.64; N, 6.80; P, 5.01. Found: C, 66.82; H, 8.83; N, 7.10; P, 5.14.
1 -[3 -[[(Diphenylphosphinyl)acetyl]amino]propyl] -3 -hexadecyl-
◦
◦
1H-imidazol-3-ium chloride (5f). Yield: 91%. Mp 59-60 C. 31P
crude product and the mixture was kept at -5 C for 12 h. The
obtained residue was filtered, washed with Et2O (2 ¥ 10 mL) and
NMR (121.5 MHz, CDCl3): d 30.53. 1H NMR (300 MHz, CDCl3):
maintained in vacuum (2 mm Hg) at 40 ◦C for 2 h.
3
d 0.91 (t, 3H, CH3(CH2)14CH2–N, JH–H = 7.1 Hz); 1.21-1.41
(m, 26H, CH3(CH2)13CH2CH2–N); 1.89 (appeared quintet, 2H,
1-[3-[[(Diphenylphosphinyl)acetyl]amino]propyl]-3-hexyl-1H -
imidazol-3-ium chloride (5c). Yield: 93%. Mp 159-161 ◦C. 31P
NMR (121.5 MHz, CDCl3): d 30.82. 1H NMR (300 MHz,
3
CH2CH2NHC(O), JH–H = 5.9 Hz); 2.08 (appeared quintet, 2H,
3
CH3(CH2)13CH2CH2–N, JH–H = 5.5 Hz); 3.12 (appeared q, 2H,
CH2NHC(O),3JH–H = 5.1 Hz); 3.77 (d, 2H, PCH2, 2JP–H = 13.0 Hz);
3
CDCl3): d 0.92 (t, 3H, CH3(CH2)4CH2–N, JH–H = 6.2 Hz);
3
4.24 (t, 2H, CH2CH2CH2NHC(O), JH–H = 7.5 Hz); 4.35 (t, 2H,
1.24-1.42 (m, 6H, CH3(CH2)3CH2CH2–N); 1.82-1.97 (m, 2H,
CH2CH2NHC(O)); 2.03-2.18 (m, 2H, CH3(CH2)3CH2CH2–N);
3.14 (appeared q, 2H, CH2NHC(O),3JH–H = 3.6 Hz); 3.77 (d,
2H, PCH2, 2JP–H = 13.0 Hz); 4.26 (t, 2H, CH2CH2CH2NHC(O),
3JH–H = 7.6 Hz); 4.37 (t, 2H, CH3(CH2)4CH2–N, 3JH–H = 5.7 Hz);
7.24 (br. s, 1H, C5H in Im); 7.49-7.56 (m, 6H, m-, p-H in C6H5P);
7.67 (br. s, 1H, C4H in Im); 7.89-7.95 (m, 4H, O-H in C6H5P); 9.36
CH3(CH2)14CH2–N, 3JH–H = 6.2 Hz); 7.26 (br. s, 1H, C5H in Im);
7.47-7.55 (m, 6H, m-, p-H in C6H5P); 7.75 (br. s, 1H, C4H in Im);
3
7.88-7.95 (m, 4H, O–H in C6H5P); 9.36 (br. t, 1H, NH, JH–H
5.4 Hz); 10.31 (br. s, 1H, N CH–N). IR (KBr): 510 (m), 524 (m),
696 (m), 729 (m), 745 (m), 1104 (w), 1121 (w), 1167 & 1187 (s,
=
=
nP=O), 1310 (br), 1437 & 1466 (m, nCH ), 1561 (s, nNH), 1663 (s,
2
nC=O), 2853 (s), 2927 (s), 2931 (s), 3060 (s), 3239 (m, nNH) cm-1.
Anal. calcd for C36H55ClN3O2P: C, 68.82; H, 8.82; N, 6.69; P, 4.93.
Found: C, 68.69; H, 8.91; N, 6.78; P, 4.87.
(br. t, 1H, NH, 3JH–H=5.0); 10.35 (br. s, 1H, N CH–N). IR (KBr):
=
511 (m), 522 (m), 704 (m), 729 (m), 748 (m), 1185 & 1197 (s, nP=O),
1226 (w), 1310 (br), 1439 (m, nCH2), 1550 & 1567 (m, nNH), 1649 (s,
nC=O), 2885 (s), 2950 (s), 3033 (s), 3090 (s), 3140 (s), 3192 (m) cm-1.
Anal. calcd for C26H35ClN3O2P: C, 63.99; H, 7.23; N, 8.61; P, 6.35.
Found: C, 63.84; H, 7.24; N, 8.51; P, 6.37.
1-[3-[[(Diphenylphosphinyl)acetyl]amino]propyl]-3-alkyl-1H-
imidazol-3-ium hexafluorophosphates (6a–f) (general procedure)
1-[3-[[(Diphenylphosphinyl)acetyl]amino]propyl]-3-octyl-1H -
imidazol-3-ium chloride (5d). Yield: 84%. Mp 51-52 ◦C. 31P NMR
(121.5 MHz, CDCl3): d 30.82. 1H NMR (300 MHz, CDCl3):
To a solution of the corresponding 1-[3-[[(diphenylphos-
phinyl)acetyl]amino]propyl]-3-alkyl-1H-imidazol-3-ium bromide
(2 mmol) in anhydrous CH3CN (7 mL) a solution of NaPF6
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(4 mmol) in anhydrous CH3CN (10 mL) was added. The mixture
was stirred at room temperature for 48 h. Then, the solvent was
evaporated under reduced pressure and water was added to a solid
residue (15 mL). The product was extracted into CH2Cl2 (3 ¥
15 mL) and the organic phase was washed with water (3 ¥ 10 mL).
The collected organic layers were dried over MgSO4, filtered and
the solvent was removed on a rotary evaporator. The ionic liquid
was dried by heating at 55 ◦C under vacuum (2 mm Hg) for 4 h.
7.24 (br. s, 1H, NH); 7.36 (br. s, 1H, C4H in Im); 7.46-7.50 (m,
4H, m-H in C6H5P); 7.52-7.56 (m, 2H, p-H in C6H5P); 7.72-7.77
=
(m, 4H, O–H in C6H5P); 8.81 (br. s, 1H, N CH–N). IR (nujol):
506 (w), 529 (w), 558 (w), 730 (m), 841 (s), 1168 & 1181 (s, nP=O),
1321 (m), 1440 (m, nCH ), 1564 (m, nNH), 1659 (s, nC=O), 3252 (m,
2
n
NH) cm-1. Anal. calcd for C28H39F6N3O2P2·1H2O: C, 52.25; H,
6.42; N, 6.53; F, 17.71 Found: C, 52.72; H, 6.38; N, 6.45; F, 17.44.
1-[3-[[(Diphenylphosphinyl)acetyl]amino]propyl]-3-tetradecyl-
1H-imidazol-3-ium hexafluorophosphate (6e). Yield: 80%. Mp
89-90 ◦C. 31P NMR (162 MHz, CDCl3): d 30.62; -144.30 (heptet,
PF6, 1JP–F = 708.5 Hz). 19F NMR (282.4 MHz, CDCl3): d -71.92
1-[3-[[(Diphenylphosphinyl)acetyl]amino]propyl]-3-ethyl-1H -
imidazol-3-ium hexafluorophosphate (6a). Yield: 43%. Mp 128-
129 ◦C. 31P NMR (121.5 MHz, DMSO-d6): d 27.74; -144.09
(quintet, PF6, 1JP–F = 710.8 Hz). 19F NMR (282.4 MHz, DMSO-
1
1
(d, PF6, JP–F = 712.9 Hz). H NMR (400 MHz, CDCl3): d 0.86
1
1
3
d6): d -70.09 (d, PF6, JP–F = 711.2 Hz). H NMR (300 MHz,
(t, 3H, CH3(CH2)12CH2–N, JH–H = 7.0 Hz); 1.16-1.35 (m, 22H,
3
DMSO-d6): d 1.33 (t, 3H, CH3CH2–N, JH–H = 7.3 Hz); 1.88
CH3(CH2)11CH2CH2–N); 1.71-1.83 (m, 2H, CH2CH2NHC(O));
1.88-1.99 (m, 2H, CH3(CH2)11CH2CH2–N); 3.03-3.17 (m, 2H,
3
(appeared quintet, 2H, CH2CH2NHC(O), JH–H = 5.9 Hz); 2.98
(appeared q, 2H, CH2NHC(O),3JH–H = 6.4 Hz); 3.57 (d, 2H, PCH2,
CH2NHC(O)); 3.45 (d, 2H, PCH2, JP–H = 12.8 Hz); 3.98-4.09
2
3
2JP–H = 13.7 Hz); 4.09 (t, 2H, CH2CH2CH2NHC(O), JH–H
=
(m, 4H, CH2CH2CH2NHC(O)+CH3(CH2)12CH2–N); 7.17 (br. s,
1H, C5H in Im); 7.33 (br. t, 1H, NH, 3JH–H = 5.6 Hz); 7.36 (br.s,
1H, C4H in Im); 7.41-7.48 (m, 4H, m-H in C6H5P); 7.49-7.56 (m,
2H, p-H in C6H5P); 7.71-7.76 (m, 4H, O–H in C6H5P); 8.82 (br. s,
3
7.1 Hz); 4.16 (t, 2H, CH3CH2–N, JH–H = 7.1 Hz); 7.49-7.60 (m,
6H, m-, p-H in C6H5P); 7.75 (br. s, 1H, C5H in Im); 7.78-7.86 (m,
3
5H, O–H in C6H5P+C4H in Im); 8.15 (br. t, 1H, NH, JH–H
=
=
=
5.3 Hz); 9.13 (br. s, 1H, N CH–N). IR (nujol): 509 (w), 525 (w),
1H, N CH–N). IR (nujol): 507 (w), 529 (w), 558 (w), 840 (s), 1169
558 (m), 696 (m), 729 (m), 842 (s), 1122 (w), 1166 & 1183 (s, nP=O),
& 1182 (s, nP=O), 1439 (m, nCH2), 1565 (m, nNH), 1659 (s, nC=O), 3252
(m, nNH) cm-1. Anal. calcd for C34H51F6N3O2P2: C, 57.54; H, 7.24;
N, 5.92; P, 8.73; F, 16.06. Found: C, 57.31; H, 7.29; N, 5.85; P,
8.65; F, 15.88.
1439 (m, nCH ), 1564 (m, nNH), 1664 (s, nC=O), 3252 (m, nNH) cm-1.
2
Anal. calcd for C22H27F6N3O2P2: C, 48.81; H, 5.03; N, 7.76; P,
11.44, F, 21.05. Found: C, 48.89; H, 5.07; N, 7.69; P, 11.30, F,
20.94.
1-[3-[[(Diphenylphosphinyl)acetyl]amino]propyl]-3-hexadecyl-
1H-imidazol-3-ium hexafluorophosphate (6f). Yield: 88%. Mp
96-97 ◦C. 31P NMR (121.5 MHz, CDCl3): d 30.71, -144.20
(quintet, PF6, 1JP–F = 712.8 Hz). 19F NMR (282.4 MHz, CDCl3):
d -72.00 (d, PF6, 1JP–F = 712.9 Hz). 1H NMR (300 MHz, CDCl3):
1-[3-[[(Diphenylphosphinyl)acetyl]amino]propyl]-3-butyl-1H -
imidazol-3-ium hexafluorophosphate (6b). Yield: 73%. Mp 57-
58 ◦C. 31P NMR (121.5 MHz, DMSO-d6): d 27.78; -144.07
(quintet, PF6, 1JP–F = 712.8 Hz). 19F NMR (282.4 MHz, DMSO-
1
1
3
d6): d -70.09 (d, PF6, JP–F = 711.2 Hz). H NMR (300 MHz,
d 0.93 (t, 3H, CH3(CH2)14CH2–N, JH–H = 6.9 Hz); 1.21-1.39
3
DMSO-d6): d 0.90 (t, 3H, CH3(CH2)2CH2–N, JH–H = 7.5 Hz);
(m, 26H, CH3(CH2)13CH2CH2–N); 1.85 (appeared quintet, 2H,
3
1.24 (sextet, 2H, CH3CH2CH2CH2–N); 1.73 (appeared quintet,
CH2CH2NHC(O), JH–H = 6.2 Hz); 2.01 (appeared quintet, 2H,
3
3
2H, CH2CH2NHC(O), JH–H = 7.3 Hz); 1.93 (appeared quintet,
CH3(CH2)13CH2CH2–N, JH–H = 5.5 Hz); 3.17 (appeared q, 2H,
2H, CH3CH2CH2CH2–N, 3JH–H = 6.4 Hz); 3.02 (appeared q, 2H,
CH2NHC(O),3JH–H = 6.2 Hz); 3.63 (d, 2H, PCH2, 2JP–H = 13.7 Hz);
CH2NHC(O),3JH–H = 5.5 Hz); 3.52 (d, 2H, PCH2, 2JP–H = 13.0 Hz);
4.08-4.13 (m, 4H, CH2CH2CH2NHC(O)+CH3(CH2)14CH2-N);
7.23 (br. s, 1H, C5H in Im); 7.44 (br. s, 2H, C4H in Im+NH);
7.50-7.62 (m, 6H, m-, p-H in C6H5P); 7.78-7.84 (m, 4H, O-H in
3
4.11 (t, 2H, CH2CH2CH2NHC(O), JH–H = 7.1 Hz); 4.22 (t, 2H,
CH3(CH2)2CH2–N, 3JH–H = 6.6 Hz Hz); 7.54-7.64 (m, 6H, m-, p-H
in C6H5P); 7.80-7.90 (m, 6H, O–H in C6H5P+C5H in Im+C4H in
C6H5P); 8.93 (br. s, 1H, N CH–N). IR (nujol): 508 (w), 529 (w),
=
Im); 8.21 (br. t, 1H, NH, 3JH–H = 5.5 Hz); 9.18 (br. s, 1H, N CH–
558 (m), 695 (w), 730 (w), 742 (w), 838 (s), 857 (s), 1123 (w),
=
N). IR (nujol): 509 (w), 525 (w), 558 (m), 696 (w), 729 (w), 842 (s),
1181 (s, nP=O), 1439 (m, nCH ), 1565 (m, nNH), 1659 (s, nC=O), 3256
2
1122 (w), 1166 & 1183 (s, nP=O), 1439 (m, nCH ), 1564 (m, nNH), 1664
(m) cm-1. Anal. calcd for C36H55F6N3O2P2: C, 58.61; H, 7.51; N,
5.70; P, 8.40; F, 15.45. Found: C, 59.07; H, 7.79; N, 5.12; P, 7.77;
F, 15.27.
2
(s, nC=O), 3252 (m, nNH) cm-1. Anal. calcd for C24H31F6N3O2P2: C,
50.62; H, 5.49; N, 7.38; P, 10.88; F, 20.02. Found: C, 50.74; H,
5.39; N, 7.29; P, 10.68; F, 19.87.
1-[3-[[(Diphenylphosphinyl)acetyl]amino]propyl]-3-hexyl-1H -
imidazol-3-ium hexafluorophosphate (6c). A solution of 1-[3-
[[(diphenylphosphinyl)acetyl]amino]propyl]-3-hexyl-1H -imida-
zol-3-ium bromide (2 mmol), NaPF6 (4 mmol) and water (15 mL)
was stirred at room temperature for 48 h. The product was
extracted into CH2Cl2 (3 ¥ 15 mL) and the organic phase was
washed with water (3 ¥ 10 mL). The collected organic layers
were dried over MgSO4, filtered and the solvent was removed
on a rotary evaporator. The ionic liquid was dried by heating
at 55 ◦C under vacuum (2 mm Hg) for 4 h. Yield: 87%. Mp
154-155 ◦C. 31P NMR (162 MHz, CDCl3): d 31.37; -144.31
(heptet, PF6, 1JP–F = 708.7 Hz). 19F NMR (282.4 MHz, CDCl3: d
-72.17 (d, PF6, 1JP–F = 712.9 Hz). 1H NMR (400 MHz, CDCl3):
1-[3-[[(Diphenylphosphinyl)acetyl]amino]propyl]-3-octyl-1H -
imidazol-3-ium hexafluorophosphate (6d). Yield: 81%. Mp 114-
◦
115 C. 31P NMR (162 MHz, CDCl3): d 31.24; -144.30 (heptet,
1
PF6, JP–F = 708.8 Hz). 19F NMR (282.4 MHz, CDCl3): d
-71.91 (d, PF6, 1JP–F = 712.9 Hz). 1H NMR (400 MHz, CDCl3):
3
d 0.86 (t, 3H, CH3(CH2)6CH2–N, JH–H = 6.8 Hz); 1.17-1.32
(m, 10H, CH3(CH2)5CH2CH2–N); 1.80 (appeared quintet, 2H,
3
CH2CH2NHC(O), JH–H = 6.1 Hz); 1.95 (appeared quintet, 2H,
3
CH3(CH2)5CH2CH2–N, JH–H = 5.8 Hz); 3.11 (appeared q, 2H,
CH2NHC(O),3JH–H = 5.8 Hz); 3.46 (d, 2H, PCH2, 2JP–H = 12.8 Hz);
3
4.03 (t, 2H, CH2CH2CH2NHC(O), JH–H = 6.8 Hz); 4.06 (t, 2H,
CH3(CH2)6CH2–N, 3JH–H = 7.5 Hz); 7.16 (br. s, 1H, C5H in Im);
4176 | Dalton Trans., 2010, 39, 4170–4178
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3
d 0.86 (t, 3H, CH3(CH2)4CH2–N, JH–H = 6.8 Hz); 1.24-1.31
Solid-state structures of ionic liquids
(m, 6H, CH3(CH2)3CH2CH2–N); 1.81 (appeared quintet, 2H,
Crystals of 4d and 6c suitable for X-ray diffraction were grown
by recrystallization from EtOAc–Et2O–EtOH (4d) and EtOH (6c)
at -20 ◦C. X-Ray diffraction experiments were carried out with a
Bruker SMART APEX2 CCD using graphite monochromated
3
CH2CH2NHC(O), JH–H = 7.6 Hz); 1.97 (appeared quintet, 2H,
3
CH3(CH2)3CH2CH2–N, JH–H = 6.4 Hz); 3.13 (appeared q, 2H,
CH2NHC(O),3JH–H = 5.7 Hz); 3.47 (d, 2H, PCH2, 2JP–H = 12.8 Hz);
4.04-4.09 (m, 4H, CH2CH2CH2NHC(O) + CH3(CH2)4CH2–N);
7.16 (t, 1H, C5H in Im, 3JH–H = 1.7 Hz); 7.37 (t, 1H, C4H in Im,
3JH–H = 1.7 Hz); 7.41 (br. t, 1H, NH, 3JH–H = 5.2 Hz); 7.46-7.50 (m,
4H, m-H in C6H5P); 7.53-7.57 (m, 2H, p-H in C6H5P); 7.73-7.78
˚
Mo-Ka radiation (l = 0.71073 A, w-scans) at 120 K. The
structures were solved by direct methods and refined by the
full-matrix least-squares against F2 in anisotropic approximation
for no-hydrogen atoms. Hydrogen atoms of NH groups were
located from the Fourier density synthesis and refined in isotropic
approximation. The H(C) atom positions in these structures were
calculated and refined in isotropic approximation in riding model
with the Uiso(H) parameters equal to 1.2 Ueq(Ci), for methyl groups
equal to 1.5 Ueq(Cii), where U(Ci) and U(Cii) are, respectively,
the equivalent thermal parameters of the carbon atoms to which
corresponding H atoms are bonded. In the case of 4d, the hydrogen
atom of OH group of the solvent ethanol molecule hasn’t been
localized due to its strong disorder. Crystal data and structure
refinement parameters for 4d and 6c are given in Table S2 (see
ESI†). All calculations were performed using the SHELXTL
software.22 CCDC reference numbers 758107 (4d) and 758108
(6c). For crystallographic data in CIF format or other electronic
formate see the ESI.†
(m, 4H, O–H in C6H5P); 8.95 (br. s, 1H, N CH–N). 13C NMR
(100.61 MHz, CD3CN): d 13.11 (CH3), 21.96, 25,25, 29.13, 29.29
(four s, CH2 in hexyl), 30.62 (CH2CH2N), 34.84 (NHCH2), 38.41
=
1
(d, PCH2, JPC = 62.4 Hz), 46.01 (NIm–CH2), 49.42 (NIm–CH2),
122.06 (C4(Im)), 122.30 (C5(Im)), 128.71 (d, m-C in C6H5, 3JPC
=
2
11.7 Hz), 130.54 (d, o-C in C6H5, JPC = 9.5 Hz), 131.91 (p-C
1
in C6H5), 132.42 (d, ipso-C in C6H5, JPC = 102.7 Hz), 135.64
(C2(Im)), 165.07 (d, C(O), 2JPC = 5.9 Hz). IR (nujol): 818 (s), 842
(s), 1171 &1182 (s, nP=O), 1441 (m, nCH ), 1572 (m, nNH), 1657 (s,
2
nC=O), 2922, 2959, 3253 cm-1. Anal. calcd for C26H35F6N3O2P2: C,
52.26; H, 5.90; N, 7.03; F, 19.08. Found: C, 52.45; H, 5.85; N, 6.91,
F, 18.66.
Preparation of complexes 7a,b
An ethanolic solution (4 mL) of the corresponding metal salt
(0.098 mmol) was added dropwise to a solution of the ligand 4c
(119.4 mg, 0.2 mmol) in 4 mL of C2H5OH (the ratio L : M = 2 : 1).
The resulting mixture was left under ambient conditions for 2 h
and evaporated to a volume of ~1 mL. Addition of ether (5 mL) to
the reaction solution afforded precipitation of the corresponding
complexes which were filtered off, washed with 10 mL of Et2O and
dried in vacuum.
Recovery of actinides and rare-earth elements by solid phase
extractants
For the preparation of sorbents, the solid matrixes of polyacryloni-
trile fiber (discs, 1 cm diameter, m = 10 g) and multi-walled carbon
R
nanotubes Tauniteꢀ (20 mg, Russia) were treated by solutions of
FILs (30 mg) in dichloroethane or ethanol (0.5 ml) followed by air
drying. In experiments, radio-chemical isotopes 239Pu and 152–154Eu
radionuclides purchased from “Isotop” company (Russia) were
used. The experiments were performed under static conditions
at the aqueous phase, volume 2 mL (3 M HNO3). The aqueous
solution of the corresponding radionuclide (concentration ranged
from 2 ¥ 10-5 to 4 ¥ 10-5 mol L-1) together with a sample of the
sorbent was stirred for 2 h. As was found previously, this is a
time which is longer than that required for the system to reach
equilibrium. The sorption activity was estimated on the basis
of radionuclide recovery (%) determined by radioactivity before
and after the experiment using an “Alpha Analyst” (Canberra)
instrument and radiometer UMF-2000 (Russia). The experiments
were done in the radiochemical laboratory of Vernadsky Institute
of Geochemistry and Analytical Chemistry RAS having the
corresponding license.
[Eu{bis[1-[3-[[(diphenylphosphinyl)acetyl]amino]propyl]-3-hexyl-
1H-imidazol-3-ium]}Br2Cl3] 7a. Yield: 56% (white solid).
◦
Mp 78-81 C.31P NMR (121.5 MHz, CD3OH): d 3.06.1H
NMR (300 MHz, CD3OH): 0.99 (t, 3H, CH3(CH2)4CH2–N,
3JH–H = 6.8 Hz); 1.37-1.52 (m, 6H, CH3(CH2)3CH2CH2–N);
3
2.05 (appeared q, 2H, CH3(CH2)3CH2CH2–N, JH–H = 6.9 Hz);
2.41-2.67 (m, 4H, CH2CH2NHC(O) + CH2NHC(O)); 4.08 (br. s,
2H, PCH2); 4.40 (t, 2H, CH2CH2CH2NHC(O), 3JH–H = 7.3 Hz);
3
4.86 (t, 2H, CH3(CH2)4CH2–N, JH–H = 6.8 Hz); 4.99 (br. s, 1H,
NH); 6.73-6.91 (m, 4H, O–H in C6H5P); 7.24-7.34 (m, 4H, m-H
in C6H5P); 7.52-7.57 (m, 2H, p-H in C6H5P); 7.87 (br. s, 1H, C5H
4
=
in Im); 8.06 (br. s, 1H, C H in Im); 9.50 (br. s, 1H, N CH–N).
IR (KBr, cm-1): 507, 528, 694, 735, 1095, 1124, 1161 (nP=O), 1438
(nCH ), 1563 (nNH), 1588, 1628 (nC=O), 2858, 2930, 3056, 3205
2
(nNH), 3348. Anal. calcd for C52H70Br2Cl3EuN6O4P2: C, 47.20; H,
5.33; N, 6.35. Found: C, 47.18; H, 5.38; N, 6.41.
Acknowledgements
[Eu{bis[1-[3-[[(diphenylphosphinyl)acetyl]amino]propyl]-3-hexyl-
1H-imidazol-3-ium]}Br2(NO3)3] 7b. Yield: 78%, white solid, Mp.
87-89 ◦C.31P NMR (121.5 MHz, EtOH): d -12.36. IR (nujol, cm-1):
507 (w), 528 (w), 695 (w), 737 (m), 1031 (w, nas(NO2)), 1097 (w),
1124, 1138, 1162 (s, nP=O), 1314 (s, nas(NO2)), 1438 (s, nCH2 ),
The authors are grateful to Russian Basic Research Foundation
(grant 08-03-00766) for the financial support.
References
=
1470 (s, n(N O)), 1563 (m, nNH), 1588, 1628 (s, nC=O), 3055
1 For leading reviews see: (a) T. Welton, Chem. Rev., 1999, 99, 2071;
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H, 5.09; N, 8.79.
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Dalton Trans., 2010, 39, 4170–4178 | 4177
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View Online
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4178 | Dalton Trans., 2010, 39, 4170–4178
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The Royal Society of Chemistry 2010
©