Synthesis and coordination properties of new preorganized ligand on the triphenylphosphine oxide platform

Article abstract of DOI:10.1007/s11172-013-0146-6

Tris(2-cyanomethoxyphenyl)phosphine oxide was synthesized by the reaction of tris-(2-hydroxyphenyl)phosphine oxide with chloroacetonitrile. Its coordination properties were studied for the complexation with neodymium(III) and copper(ii) nitrates using vibrational spectroscopy, NMR, and quantum chemical calculations.

Full text of DOI:10.1007/s11172-013-0146-6

Russian Chemical Bulletin, International Edition, Vol. 62, No. 4, pp. 1086—1090, April, 2013
1086
Synthesis and coordination properties of new preorganized
ligand on the triphenylphosphine oxide platform*
I. Yu. Kudryavtsev, T. V. Baulina, M. P. Pasechnik, R. R. Aisin, S. V. Matveev, P. V. Petrovskii,† and E. E. Nifant´ev
A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences,
28 ul. Vavilova, 119991 Moscow, Russian Federation.
Fax: +7 (499) 135 5085. Eꢀmail: zaq@ineos.ac.ru
Tris(2ꢀcyanomethoxyphenyl)phosphine oxide was synthesized by the reaction of trisꢀ
(2ꢀhydroxyphenyl)phosphine oxide with chloroacetonitrile. Its coordination properties were
studied for the complexation with neodymium(III) and copper(II) nitrates using vibrational
spectroscopy, NMR, and quantum chemical calculations.
Key words: tris(2ꢀcyanomethoxyphenyl)phosphine oxide, neodymium(III) complexes,
copper(II) complexes, Raman spectroscopy, IR spectroscopy, NMR spectroscopy, quantum
chemical calculations.
A promising approach to the development of new
ligands and extractants for hydrometallurgy is based on
the increase in denticity of ligands, that makes it possiꢀ
ble to obtain more stable complexes. At the same time,
more rigid molecular framework increases selectivity
of complexation. The use of tripodal structures based on
the conformationally rigid platform makes it possible to
develop ligands combining both the efficiency and the seꢀ
lectivity of complexation. In this connection, in the last
decades tripodal ligands of different structure have attractꢀ
ed a growing attention, in particular, those on the triarylꢀ
methane platform1,2 containing the central triphenylꢀ
methane core with the chains bearing donor atoms atꢀ
tached to the phenyl rings.
bination of conformational rigidity of the triphenylphosꢀ
phine oxide core of the ligand molecule and the presence
of several additional donor atoms in the side chains create
conditions for the formation of a preorganized ligand
environment that provides a concerted coordination of all
the donating groups to the metal cation.
Tris(2ꢀcyanomethoxy)phosphine oxide 2 was obtained
in accordance with Scheme 1.
Scheme 1
Triarylphosphine oxides are the structural analogs of
triarylmethanes and are an attractive platform for the conꢀ
struction of tripodal ligands, since they contain an addiꢀ
tional coordination center, the phosphoryl group. It is
known that triarylphosphine oxide molecules, including
those of tris(2ꢀmethylphenyl)phosphine oxide3 and trisꢀ
(2ꢀhydroxyphenyl)phosphine oxide (1),4 have a propeller
conformation, with the substituents in orthoꢀposition beꢀ
ing directed to the same side as the phosphoryl group. The
present work is devoted to the synthesis and coordination
properties of the structurally related potentially tetraꢀ
dentate ligand tris(2ꢀcyanomethoxyphenyl)phosphine
oxide (2), which is derived from phosphine oxide 1. It
could have been suggested that the propeller conformaꢀ
tion of ligand 2 would secure the orientation of the three
nitrile and the phosphoryl groups to the same side. A comꢀ
Precursor 1 was synthesized by the reaction discovered
in 1981 by L. Melvin,5 which included a rearrangement of
aryl phosphates to 2ꢀhydroxyarylphosphonates on treatꢀ
ment with metallating agents. This approach was further
developed by other researchers6 and used for the preparaꢀ
tion of hydroxyarylenebis(phosphonates),7 bis(2ꢀhydroxyꢀ
aryl)phosphinates,8 as well as tris(2ꢀhydroxyaryl)phosꢀ
phine oxides8,9 of the type 1.
* Dedicated to Academician of the Russian Academy of Sciences
I. P. Beletskaya on the occasion of her anniversary.
† Deceased.
Phosphine oxide 1 was synthesized by treatment of
triphenyl phosphate with lithium diisopropylamide at from
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 1085—1089, April, 2013.
1066ꢀ5285/13/6204ꢀ1086 © 2013 Springer Science+Business Media, Inc.

Tris(2ꢀcyanomethoxyphenyl)phosphine oxide
Russ.Chem.Bull., Int.Ed., Vol. 62, No. 4, April, 2013
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Table 1. IR and Raman spectroscopic data for compounds 1—4 (/cm–1
)
Compound
IR
RS,
(CN)
(P=O)
 (NO3)
 (NO3)
 (NO3)
(OH)
5
1
2
(2ꢀHOC6H4)3P=O (1)
1090
—
—
—
—
—
—
2600—3600
(br.s)
—
(2ꢀNCCH2OC6H4)3P=O
(L) (2)
1184
—
2262, 2242
Nd(NO)3•2L•2H2O (3)
Cu(NO3)2•2L•3H2O (4)
1146
1146, 1123
1490
1380
1316
1380
1033
1380
3430
3390, 3070
2261, 2247
2261, 2247
–80 to –90 C.* The process included the metallation of
the benzene ring at orthoꢀposition with subsequent migration
of phosphorus to carbon. The structure of compound 1 was
confirmed by the elemental analysis data, IR and NMR
spectroscopy (Tables 1 and 2), and Xꢀray diffraction studies.4
The main feature of the structure of phosphine oxide 1
in solutions and in crystal is the formation of intraꢀ and
intermolecular hydrogen bonds between the phenolic
hydroxy groups and the oxygen atom of the phosphoryl
group. Thus, the IR spectrum of compound 1 in the solid
state exhibits a broad absorption band related to the
stretching vibrations of the OH groups involved in the
hydrogen bonding (3600—2600 cm–1). The absorption
band of the P=O group is shifted to the lowꢀfrequency
region as compared to that of triphenylphosphine oxide
(1200 cm–1) by more than 100 cm–1 (1090 cm–1), that is
explained by the trifurcate hydrogen bond formed by the
phosphoryl oxygen atom with three hydroxy groups. From
the IR spectra of compound 1 in solutions, it follows that
the intramolecular hydrogen bond still exists in chloroꢀ
form and is destroyed in DMSO, while different species
are in the equilibrium in acetonitrile.
In the global minimum, molecule 2 has a propeller
conformation, in which the blades of the phenyl rings are
turned along the C—P bonds so that the torsional angles
O—P—C—C are 46—50 (Fig. 1). The oxygen atoms of
the cyanomethoxy groups are above the plane formed by
the carbon atoms of three C—P bonds and on the same
side with the P=O group. Two —C—CN groups are virꢀ
tually parallel to each other and symbatic to the P=O
bond, the third group is directed to the opposite side.
The theoretical analysis of vibrations of molecule 2 in
this conformation showed, in particular, that the frequenꢀ
cy 1193 cm–1 corresponded to the vibration of the P=O
bond. However, this vibration, overlapping with vibrations
of the P—C bonds and close in frequency vibrations of
phenyl rings, also contribute to several frequencies in the
region 1125—1260 cm–1. Characteristic vibrations of
the nitrile bonds have the frequencies 2266, 2268, and
2287 cm–1, with the virtually overlapped first two bands
being related to the vibrations of the oppositely directed
bonds, while the band of higher frequency being associatꢀ
ed with one of the parallel bonds. This bond structurally
differs from two other ("the oppositely directed") bonds by
its parallel orientation with respect to its phenyl ring,
whereas two other bonds are oriented at the angle of ~60
to the plane of "their own" phenyl rings.
The 31P{1H} NMR spectra exhibit singlets, whose
chemical shift strongly depends on the nature of the solꢀ
vent and is upfield shifted by 10—15 ppm on going to the
solvents capable of destroying hydrogen bonds.
The IR spectrum of phosphine oxide 2 exhibits an abꢀ
sorption band of the phosphoryl group at 1184 cm–1. No
Tris(2ꢀhydroxyphenyl)phosphine oxide 1 reacted with
chloroacetonitrile in the presence of K2CO3 and KI in
DMF upon heating to 50 C. Cyanomethoxy derivative 2
was isolated as colorless crystals well soluble in ethyl alꢀ
cohol, DMF, chloroform, and acetone. The structure of
compound 2 was confirmed by the elemental analysis,
vibrational spectroscopy (IR, Raman), and NMR spectroꢀ
scopy (1H, 31P, and 13C) (see Tables 1 and 2). To study the
coordination potentialities of ligand 2, as well as to corꢀ
rectly interpret vibrational spectra, we carried out quanꢀ
tum chemical calculations for the molecular conformaꢀ
tions and the normal vibrational modes.
* The published procedure9 was slightly modified: the metallaꢀ
tion was carried out at lower temperature, the workꢀup of
the reaction mixture and the isolation of the product were simꢀ
plified.
Fig. 1. Conformation of tris(2ꢀcyanomethoxyphenyl)phosphine
oxide molecule 2 in the region of the global minimum according
to quantum chemical calculations.

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Kudryavtsev et al.
Table 2. 1H, 1H{31P}, 13C{1H}, and 31P{1H} NMR spectra of compounds 1—4
Comꢀ
pound
Solvent
, J/Hz, 1/2/Hz
1H
1H{31P}
13C{1Н}
31P{1H} (s)
35.95
1
DMSOꢀd6
6.85 (dd, 3 H, H(3),
3J3,4 = 8.2, 4JH,P = 5.4);
6.89 (tdd, 3 H, H(5),
3J5,4 = 3J5,6 =7.5,
4J5,3 = 2.3, 4JH,P = 1.0);
7.41 (br.t, 3 H, H(4),
3J4,3 = 3J4,5 = 7.7);
7.44 (ddd, 3 H, H(6),
3J6,5 = 7.7, 4J6,4 = 1.7,
3JH,P = 14.3); 10.77
(s, 3 H, OH)
6.86 (d, 3 H, H(3), 3J3,4 = 8.2);
—
6.90 (t, 3 H, H(5), 3J5,4
=
= 3J5,6 =7.5); 7.42 (td, 3 H,
H(4), 3J4,3 = 3J4,5 = 7.8,
4J4,6 = 1.7); 7.46 (d, 3 H,
H(6), 3J6,5 = 7.7); 10.77
(s, 3 H, OH)
CD3CN
DMF
—
—
—
—
—
—
38.27
40.46
51.60
—
CDCl3
6.90 (td, 3 H, H(5), 3J5,4
= 3J5,6 = 7.5, 4JH—P = 2.7);
=
6.90 (t, 3 H, H(5), 3J5,4
= 3J5,6 = 7.5); 6.95—7.05
=
6.95—7.06 (m, 6 H, H(3), H(6)); (m, 6 H, H(3), H(6)); 7.46
7.46 (t, 3 H, H(4), 3J4,3
=
(t, 3 H, H(4), 3J4,3 = 3J4,5
=
= 7.8); 9.42 (s, 3 H, OH)
= 3J4,5 = 7.8); 9.42 (s, 3 H, OH)
2
CD3CN
4.68 (s, 6 H, CH2O); 7.14 (dd,
4.68 (s, 6 H, CH2O); 7.14
55.04 (s, CH2O); 114.61
21.46
3 H, H(3), 3J3,4 = 7.9, 4JH,P
=
(d, 3 H, H(3), 3J3,4 = 8.4);
(d, C(3), 1JCH 6.53); 116.28 (1/2 = 3)
(s, CN); 123.22 (d, C(1),
1JCP = 109.62); 124.05
= 4.9); 7.21 (tdd, 3 H, H(5),
7.22 (t, 3 H, H(5), 3J5,4
= 7.5, 3J5,6 = 7.6); 7.54
=
3J5,4 = 7.5, 3J5,6 = 7.6, 4J5,3
=
= 0.8, 4JH,P = 2.2); 7.54 (ddd,
(dd, 3 H, H(6), 3J6,5 = 7.6,
4J6,4 = 1.7); 7.64 (ddd, 3 H,
H(4), 3J4,3 = 8.4, 3J4,5 = 7.5,
4J4,6 = 1.7)
(d, C(5), 1JCH = 12.03);
135.02 (d, C(4), 1JCH
=
= 2.06); 135.27 (d, C(6),
1JCH = 8.25); 159.09
(d, C(2), 1JCP = 2.06)
3 H, H(6), 3J6,5 = 7.6, 4J6,4
= 1.7, 3JH,P = 14.8); 7.64
=
(dddd, 3 H, H(4), 3J4,3 = 8.4,
3J4,5 = 7.5, 4J4,6 = 1.7,
5JH,P = 1.1)
3
4
CD3CN
CD3CN
4.25 (s, 6 H, OCH2); 7.25—7.40
(m, 3 H, H(3)); 7.46 (br.s, 3 H,
H(5)); 7.89 (t, 3 H, H(4),
3J4,5 = 3J4,3 = 7.9); 9.47
(br.s, 3 H, H(6))
—
—
—
—
143.65
(1/2 = 50)
5.30 (br.s, 6 H, OCH2);
6.75—8.20 (m, 12 H, Ar)
—
vibration of the nitrile bond was detected, that is not unꢀ
common, since the intensity of absorption for this band
depends on the bond environment.10 It the Raman spectrum,
the vibration of the CN bonds is observed as two weak
lines at 2242 and 2262 cm–1, with the band of higher
frequency being stronger, that agrees with the calculations.
The 31P{1H} NMR spectrum exhibits a singlet in the
region characteristic of triarylphosphine oxides; the H
and 13C NMR spectra correspond to the structure of comꢀ
pound 2.
Coordination properties of the preorganized tripodal
ligand 2 on the triphenylphosphine oxide platform were
studied for the complexation with neodymium(III) and
copper(II) nitrates. The complexes obtained were characꢀ
terized by IR, Raman, and NMR spectroscopy (see Tables 1
and 2). Unfortunately, the low solubility of these comꢀ
plexes in low polarity solvents considerably limits the posꢀ
sibilities of their studies in solutions.
The reaction of tris(2ꢀcyanomethoxyphenyl)phosphine
oxide 2 with neodymium nitrate leads to complex (3),
which according to the elemental analysis data has the
composition Nd(NO3)3•2L•2H2O.
The IR spectrum of complex 3 exhibited no absorption
band for the free P=O group (1184 cm–1), while new bands
appeared at 1146 and 1123 cm–1. The former is characterꢀ
istic11 of the vibration of coordinated P=O group. The
emergence of the latter can be explained by the fact that,
as was shown by quantum chemical calculations, the viꢀ
bration of the P=O group contributes to the frequencies of
the mixed vibrations in this region.
1
As to the cyano group, determination of its involveꢀ
ment in the coordination by spectroscopic methods is more

Tris(2ꢀcyanomethoxyphenyl)phosphine oxide
Russ.Chem.Bull., Int.Ed., Vol. 62, No. 4, April, 2013
1089
complicated problem. It is known that coordination at the
nitrogen atom leads to the increase in the vibrational freꢀ
quency of the CN bond by 30—50 cm–1, with the value
of the shift being dependent on the nature of the metal,
coordination number, and other factors. Coordination at
the triple bond is also possible, leading in this case to
a considerable decrease in the frequency of the CN vibraꢀ
In the Raman spectrum of complex 4, the lines of the
CN vibration is observed at the same frequencies as that in
the case of complex 3: at 2247 and 2261 cm–1. However,
their intensities are low with the highꢀfrequency line is the
strongest. Thus, the vibrational spectra show that the bisꢀ
ligand copper complex, like the neodymium one, is formed
due to the coordination of the phosphoryl groups.
tion, sometimes by more than 100 cm–1 12
.
The Raman
The copper complex 4 also includes the nitrate groups
and water. The coordination of these groups in complexes
3 and 4 differ from each other. Thus, if in complex 3 the
stretching vibration maximum for water is observed at
3430 cm–1 and corresponds to the absorption of the crystal
(outerꢀsphere) water, the IR spectrum of complex 4 exꢀ
hibits two absorption maxima at lower frequencies: 3390
and 3070 cm–1; a weak maximum at ~1680 cm–1 belongs
apparently to the bending vibration of water. Such a spectrum
can correspond to the innerꢀsphere coordination of water.
The band at 1380 cm–1, which corresponds to the D3h
symmetry of the "free" NO3 anion, can be assigned to the
vibrations of the nitrate groups in complex 4. A similar band
characterizes copper nitrate trihydrate Cu(NO3)2•3H2O.13
It can be suggested that the nitrate groups are either in the
axial position of the stretched coordination octahedron of
the copper cation or in the outer coordination sphere.
The 31P NMR spectrum of copper complex 4 failed to
be recorded because of the line broadening. In the 1H NMR
spectrum, the broadening of all the proton signals is obꢀ
served, including the methylene one, which is shifted
downfield by ~0.6 ppm. The protons of the aromatic rings
in the spectrum of complex 4 are found as a broad multipꢀ
let in the region  6.75—8.20, that does not allow us to
assign the signals.
spectrum of complex 3, like the spectrum of the free ligand,
exhibits two lines related to the vibrations of the CN
bonds (at 2247 and 2261 cm–1) with redistributed intenꢀ
sity, i.e., the frequency difference is only 5 cm–1. In our
opinion, such a change in the spectrum cannot indicate
coordination of the cyano group and is apparently caused
by the spatial rearrangement.
The IR spectrum of complex 3 also exhibits broad abꢀ
sorption bands of the nitrate groups coordinated in bidenꢀ
tate mode: at 1490 (5), 1316 (1), and 1033 (2) cm–1 12
.
The complex contains the outerꢀsphere water, which is
indicated by the broad band of stretching OH vibrations
with the maximum at 3430 cm–1 and the band of bending
OH vibrations at 1650 cm–1
.
The 31P NMR spectrum of neodymium complex 3
exhibits a broad signal, which is downfield shifted by
~122 ppm as compared to the spectrum of the starting
ligand, that indicates the coordination of the NdIII cation
at the oxygen atom of the phosphoryl group. In the
1H NMR spectrum of complex 3, all the proton signals are
also broadened, and the signal for the protons of the
methylene group is upfield shifted by ~0.4 ppm. The sigꢀ
nals for protons H(3), H(4), and H(5) are shifted downꢀ
field by ~0.2 ppm, whereas the signal for proton H(6) is
shifted by ~2 ppm, that confirms the coordination of the
NdIII cation at the P=O group.
In conclusion, the reaction of ligand 2 with NdIII and
CuII nitrates leads to the complexes only due to the coorꢀ
dination to the P=O group. We further plan to modify
precursor 1 with other substituents.
To sum up, the elemental analysis data, vibrational
spectroscopy, and NMR spectroscopy show that the comꢀ
plexation of ligand 2 with Nd(NO3)3•6H2O leads to the
complex [NdL2(NO3)3]•2H2O due to the coordination of
neodymium at the oxygen atom of the phosphoryl group.
It should be noted that ligand 2 is potentially tetradenꢀ
tate, i.e., the coordination to the cyano group is in princiꢀ
ple possible. However, such a coordination does not apꢀ
parently take place in the neodymium complex. In this
connection, a divalent copper having an affinity to nitroꢀ
gen atoms was chosen as the complexing metal.
The reaction of a solution of tris(2ꢀcyanomethoxyꢀ
phenyl)phosphine oxide 2 with copper nitrate leads to the
complex, which according to the elemental analysis data
has the composition Cu(NO3)2•2L•3H2O (4).
The IR spectrum of complex 4 in the region of the
P=O bond vibrations virtually does not differ from the
spectrum of complex 3: the absorption band of the free
P=O group is absent, a new band is observed at 1145 cm–1
and the absorption at 1124 cm–1 becomes stronger .Thereꢀ
fore, like in the neodymium complex 3, the phosphoryl
group is coordinated in the copper complex 4.
Experimental
1
1
H, H{31P}, 13C{1H}, and 31P{1H} NMR spectra were reꢀ
corded on a Bruker AVꢀ400 spectrometer (400.13 (1H), 161.98
(31P{1H}), and 100.61 MHz (13C{1H})). The signals of residual
protons of deuterated solvents were used as internal references
in the 1H and 1H{31P} NMR spectra, in the 13C{1H} NMR specꢀ
tra, the signal for the carbon atom of the deuterated solvent was
the internal reference, 85% aqueous H3PO4 was used as an exꢀ
ternal standard for 31P{1H} NMR spectra.
IR spectra of compounds 1—4 in Nujol and KBr pellets in
the region 400—4000 cm–1 and solutions of phosphine oxide 1 in
CDCl3, CD3CN, and DMSOꢀd6 in the region 700—4000 cm–1
with the concentrations of 0.1, 0.01, and 0.001 mol L–1 in 0.02ꢀ,
0.23ꢀ, and 0.54ꢀcm pathlength cuvettes were obtained on a Niꢀ
kolet Magna IRꢀ750 Fourierꢀtransform spectrometer. Raman
spectra of solid samples in the region 200—4000 cm–1 were reꢀ
corded on a Jobin—Yvon LabRAM Raman laser spectrometer
(Ge—Neꢀlaser, 632.8 nm).
Quantum chemical calculations at the density functional
theory (DFT) level with the PBE functional for tris(2ꢀcyanoꢀ

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Kudryavtsev et al.
methoxyphenyl)phosphine oxide 2 were performed using the
Priroda 6 (2006.08.20) software14,15 (see Ref. 16). The optimizaꢀ
tion of geometric parameters and calculations of frequencies,
shapes, and IR intensities of normal vibrations were carried out
on the L2 relativistic basis set level.17
Deuterated solvents (CDCl3, CD3CN, DMSOꢀd6) for reꢀ
cording NMR spectra (the Russian Scientific Center of Applied
Chemistry, SaintꢀPetersburg) were used without additional puꢀ
rification. Other organic solvents were purified according to the
standard procedures.18
ring. The mixture obtained was stirred for 1.5 h at ~20 C, then
most of the solvent was evaporated in vacuo, diethyl ether was
added. A white precipitate formed was filtered off, twice washed
with diethyl ether, and dried to obtain complex 3 (0.08 g, 95%)
of the composition Nd(NO3)3•2L•2H2O, m.p. 124 C (decomp.).
Found (%): C, 46.02; H, 3.20; N, 9.75; P, 4.73. C48H40N9NdO19P2.
Calculated (%): C, 46.01; H, 3.22; N, 10.06; P, 4.94.
Triaquabis[tris(2ꢀcyanomethoxyphenyl)phosphine oxide)]ꢀ
copper(II) nitrate (4). A solution of Cu(NO3)2•3H2O (0.0792 g,
0.328 mmol) in acetonitrile (5 mL) was added dropwise to
a solution of tris(2ꢀcyanomethoxyphenyl)phosphine oxide (2)
(0.1157 g, 0.261 mmol) in chloroform (4 mL) with stirring. The
mixture obtained was stirred for 2 h at ~20 C, then most of the
solvent was evaporated in vacuo, diethyl ether was added. A light
blue precipitate formed was filtered off, twice washed with diꢀ
ethyl ether, and dried to obtain complex 4 (0.08 g, 54%) of the
composition Cu(NO3)2•2L•3H2O, m.p. 125 C (decomp.).
Found (%): C, 51.07; H, 3.55; N, 9.91; P, 4.97. C48H42CuN8O17P2.
Calculated (%): C, 51.09; H, 3.75; N, 9.93; P, 5.49.
A 1.6 M solution of butyllithium in hexane (Aldrich) was
used in the work, diisopropylamine (Acros) was distilled over Na.
Elemental analysis was performed in the Laboratory of
Microanalysis of the A. N. Nesmeyanov Institute of Organoꢀ
element Compounds of the Russian Academy of Sciences.
Tris(2ꢀhydroxyphenyl)phosphine oxide (1). Step 1. A mixture
of phenol (28.2 g, 0.3 mol), phosphorus oxychloride (15.3 g,
0.1 mol), and magnesium (0.048 g, 2 mmol) was heated at 160 C
for 3 h (until the evolution of hydrogen chloride ceased). The
volatile products were evaporated in vacuo. The residue was puꢀ
rified by flash chromatography on Al2O3 to obtain triphenyl phosꢀ
phate (29.0 g, 89%), m.p. 49—50 C (hexane). 1H NMR (CDCl3),
: 7.23—7.48 (m, 5 H, Ph). 31P{1H} NMR (CDCl3), : –17.52 s.
Step 2. A solution of triphenyl phosphate (19.6 g, 0.06 mol)
in anhydrous THF (110 mL) was added over 40 min to a cooled
to –80 C solution of lithium diisopropylamide prepared
from diisopropylamine (19.4 g, 0.192 mol) in anhydrous THF
(60 mL) and a 1.6 M solution of butyllithium in hexane (120 mL),
keeping the temperature in the range from –80 to –90 C. The
reaction mixture was stirred for 1 h at this temperature and was
allowed to warm up to ~20 C. Then, water (50 mL) and conꢀ
centrated hydrochloric acid (58 mL) were added dropwise to the
reaction mixture with stirring and cooling with cold water. The
organic layer was separated, the aqueous layer was extracted with
dichloromethane (4×20 mL). The combined organic extracts
were washed with water (4×10 mL) and dried with anhydrous
sodium sulfate. The drying agent was filtered off, the filtrate was
concentrated. The crystals formed were washed with diethyl ether
to obtain product 1 (16.7 g, 87%), m.p. 216—217 C (EtOH)
(cf. Ref. 8: m.p. 215—217 C). Found (%): C, 66.27; H, 4.57;
P, 9.41. C18H15O4P. Calculated (%): C, 66.26; H, 4.63; P, 9.49.
Tris(2ꢀcyanomethoxyphenyl)phosphine oxide (2). A freshly
distilled chloroacetonitrile (11.5 g, 0.15 mol) was added to
a mixture of freshly calcined K2CO3 (27.64 g, 0.2 mol), trisꢀ
(2ꢀhydroxyphenyl)phosphine oxide (6.52 g, 0.02 mol), KI (24.9 g,
0.15 mol), and DMF (300 mL). The reaction mixture was stirred
for 8 h at ~20 C, and then for 3 h at 50—55 C. The solvent was
evaporated in vacuo to dryness and water (150 mL), sodium
metabisulfite (13.3 g, 0.07 mol), and chloroform (100 mL) were
added to the solid residue. The organic layer was separated, the
aqueous layer was extracted with chloroform (5×20 mL). The orgꢀ
anic extracts were combined, the solvent was evaporated in vacuo,
the residue was purified by column chromatography on alumina
(eluent acetone—chloroform (1 : 1)) to obtain tris(2ꢀcyanoꢀ
methoxyphenyl)phosphine oxide 2 (4.5 g, 51%), m.p. 180—182 C
(hexane). Found (%): C, 64.91; H, 3.98; N, 9.37; P, 6.90.
C24H18N3O4P. Calculated (%): C, 65.01; H, 4.09; N, 9.48; P, 6.99.
Trinitratobis[tris(2ꢀcyanomethoxyphenyl)phosphine oxide]ꢀ
neodymium(III) dihydrate (3). A solution of Nd(NO3)3•6H2O
(0.0763 g, 0.174 mmol) in acetonitrile (5 mL) was added dropꢀ
wise to a solution of tris(2ꢀcyanomethoxyphenyl)phosphine oxꢀ
ide (2) (0.0770 g, 0.174 mmol) in chloroform (4 mL) with stirꢀ
This work was financially supported in part by the Russian
Foundation for Basic Research (Project No. 12ꢀ03ꢀ31845).
References
1. H. H. Dam, D. N. Reinhoudt, W. Verboom, New J. Chem.,
2007, 31, 1620.
2. M. W. Peters, E. J. Werner, M. J. Scott, Inorg. Chem., 2002,
41, 1707.
3. T. S. Cameron, B. Dahlеn, J. Chem. Soc., Perkin Trans. 2,
1975, 1737.
4. I. Yu. Kudryavtsev, T. V. Baulina, V. N. Khrustalev, P. V.
Petrovskii, M. P. Pasechnik, E. E. Nifant´ev, Dokl. Akad.
Nauk, 2013, 448, 657 [Dokl. Chem. (Engl. Transl.), 2013,
448, No. 2, 55].
5. L. S. Melvin, Tetrahedron Lett., 1981, 22, 3375.
6. R. C. Cambie, B. D. Palmer, Austr. J. Chem., 1982, 35, 827.
7. B. Dhawan, D. Redmore, J. Org. Chem., 1984, 49, 4018.
8. K. A. Petrov, S. V. Agafonov, V. P. Pokatun, Zh. Obshch.
Khim., 1987, 57, 98 [J. Gen. Chem. USSR (Engl. Transl.),
1987, 57, No. 1].
9. B. Dhawan, D. Redmore, Synth. Commun., 1987, 17, 465.
10. L. J. Bellamy, The InfraꢀRed Spectra of Complex Molecules,
4th ed., Methuen, London; Wiley, New York, 1962, 425 pp.].
11. W. Levanson, E. H. Newman, M. Webster, Polyhedron, 2000,
19, 2697.
12. K. Nakamoto, Infrared and Raman Spectra of Inorganic and
Coordination Compounds, 4th ed., Wiley, New York—Chichꢀ
ester—Brisbane—Toronto—Singapure, 1986.
13. J. R. Ferraro, J. Mol. Spectrosc., 1960, 4, 99.
14. D. N. Laikov, Chem. Phys. Lett., 1997, 281, 151.
15. D. N. Laikov, Y. A. Ustynyuk, Russ. Chem. Bull. (Int. Ed.),
2005, 54, 820 [Izv. Acad. Nauk, Ser. Khim., 2005, 804].
16. J. P. Perdew, K. Burke, M. Ernzerhof, Phys. Rev. Lett., 1996,
77, 3865.
17. D. N. Laikov, Chem. Phys. Lett., 2005, 416, 116.
18. W. L. F. Armarego, C. L. L. Chai, Purification of Laboratory
Chemicals, ButterworthꢀHeinemann, 2009.
Received December 25, 2012;
in revised form February 11, 2013