Coordination chemistry of 2,6-bis(diphenylphosphorylmethyl)-4-methylphenol

Article abstract of DOI:10.1007/s11172-006-0150-1

The trifunctional ligand, 2,6-bis(diphenylphosphorylmethyl)-4-methylphenol (L₂), forms complexes with cerium(III) nitrate having a ligand to metal ratio of 1 : 1, 2 : 1, and 3 : 1. The structures of these complexes in the solid state and in sol

Full text of DOI:10.1007/s11172-006-0150-1

Russian Chemical Bulletin, International Edition, Vol. 54, No. 11, pp. 2519—2534, November, 2005
2519
Coordination chemistry of
2,6ꢀbis(diphenylphosphorylmethyl)ꢀ4ꢀmethylphenol*
A. G. Matveeva,ꢀ E. I. Matrosov, Z. A. Starikova, G. V. Bodrin,
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 (495) 135 6549. Eꢀmail: phoc@ineos.ac.ru
The trifunctional ligand, 2,6ꢀbis(diphenylphosphorylmethyl)ꢀ4ꢀmethylphenol (L2), forms
complexes with cerium(III) nitrate having a ligand to metal ratio of 1 : 1, 2 : 1, and 3 : 1. The
structures of these complexes in the solid state and in solution were studied by Xꢀray diffracꢀ
tion, IR and NMR (1H and 31P) spectroscopy, and conformational analysis (molecular meꢀ
chanics). The 2 : 1 complexes of L2 with lanthanum(III) and neodymium(III) nitrates were
synthesized and characterized. In all complexes, the neutral ligand is coordinated through both
phosphoryl oxygen atoms. The hydroxy oxygen atom is coordinated only in some complexes,
and the hydrogen atom of the hydroxy group is involved in hydrogen bonding. The composiꢀ
tions and structures of the resulting complexes depend on the method of synthesis and the
nature of solvent. The ligand was found to undergo easy innerꢀsphere oxidation. The structure
of one of the transformation products was established by Xꢀray diffraction. Unlike the coordiꢀ
nated ligand, the free ligand is very stable to oxidation.
Key words: 2,6ꢀbis(diphenylphosphorylmethyl)ꢀ4ꢀmethylphenol, complexes, lanthanides,
structure, hydrogen bonds, solutions.
Bisꢀ and polyphosphoryl compounds containing an
aromatic moiety and the phosphorylmethyl groups in the
ortho and meta positions of the benzene ring are conveꢀ
nient extractants for separation of transuranium and rareꢀ
earth metals from aqueous solutions of nitric acid.1—6 In
particular, reagents L1 containing substituents in the
meta positions exhibit high separation factors ( f ) with
respect to the EuIII/AmIII pair. However, the absolute
partition coefficients D = [M]org/[M]aq are small.
tion properties analogous to those of L1, because the main
ligand contour remains unchanged. At the same time,
additional coordination of the phenolic OH group should
increase stability of the extracted complexes and, conseꢀ
quently, increase the extraction coefficients with retenꢀ
tion of the selectivity level typical of L1, because the phosꢀ
phoryl groups will remain the main coordinating centers.
Actually, already our first experiments on extraction of
UVI, AmIII, and EuIII from aqueous solutions of nitric
acid with solutions of L2 in dichloroethane have showed7
that the efficiency of extraction (D) increases by an order
of magnitude compared to that of the prototype, viz.,
dioxide L1 (R = Ph), the separation factor of the metꢀ
als ( f ) remaining the same (more detailed data will be
published elsewhere).
Coordination chemistry of ligand L2 is poorly known.
Only two 1 : 1 complexes with erbium8 and cerium9 niꢀ
trates were characterized.
R = Ar, Alk, AlkO
In the present study, the coordination ability of L2 was
studied using complexation with cerium(III) nitrate as an
example. The 2 : 1 complexes with neodymium(III) and
lanthanum(III) nitrates were examined in less detail. Here,
we report only data necessary for comparison. Since the
resulting complexes are unstable during storage, we studꢀ
ied also the properties and structures of the phenol and its
potassium salt in solution and in the solid state and examꢀ
Modified ligand L2 containing an additional coordiꢀ
nating center in the second position of the benzene ring
would be expected to exhibit the coordination and extracꢀ
* Dedicated to Corresponding Member of the Russian Academy
of Sciences T. A. Mastryukova.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2440—2454, November, 2005.
1066ꢀ5285/05/5411ꢀ2519 © 2005 Springer Science+Business Media, Inc.

2520
Russ.Chem.Bull., Int.Ed., Vol. 54, No. 11, November, 2005
Matveeva et al.
186—187 (from methyl ethyl ketone) (cf. lit. data8: m.p.
176—178 °C (from ethyl acetate)). 31P—{1H} NMR (CDCl3):
δ
ined the ability of the ligand and its complexes to be
oxidized.
P 35.72 (cf. lit. data8: δP 38.11). Ligand L2 is soluble in benzene
(moderately), chloroform, dichloroethane, DMSO, acetone, and
acetonitrile (moderately on heating) and insoluble in water. The
1H and 31P NMR spectroscopic parameters are given in Table 1.
Potassium 2,6ꢀbis(diphenylphosphorylmethyl)ꢀ4ꢀmethylphenꢀ
oxide (1). A solution of ligand L2 (1.37 g, 0.00256 mol) in ethaꢀ
nol (15 mL) was added to a solution of potassium ethoxide,
which was prepared by dissolving potassium metal (0.1 g,
0.00256 gꢀat) in ethanol (15 mL) under argon. The solution
turned lemonꢀyellow. Then anhydrous benzene was added, and
the solution was concentrated to ~10 mL. Hexane was added to
the resulting benzene solution until the solution turned opaque.
Then the reaction mixture was kept in the cold. The yellow
crystalline precipitate that formed was separated, washed with a
1 : 4 benzene—hexane mixture, and dried at 140 °C in vacuo
(1—2 Torr) over P2O5 for 3 h. Salt 1 was obtained as dihydrate
in a yield of 1.42 g (97.0%) as a paleꢀyellow fineꢀcrystalline
precipitate, t.decomp. >190 °C. Found (%): C, 65.54; H, 5.29;
P, 9.99. C33H29KO3P2•2H2O. Calculated (%): C, 64.91; H, 5.45;
P, 10.14. The salt is soluble in benzene, THF, chloroform,
dichloromethane, acetone, and water. The 1H and 31P NMR
and IR spectroscopic parameters are given in Tables 1 and 2.
Synthesis of lanthanide complexes 2a, 3a—c, and 4a (general
procedure). A solution of a stoichiometric amount of Ln(NO3)3•
•6H2O (0.0003, 0.00015, or 0.0001 mol) in acetonitrile (2 mL)
was slowly added dropwise to a solution of ligand L2 (0.0003 mol)
in chloroform (1—2 mL) at ~25 °C. The solution was concenꢀ
trated to ~1.5 mL in vacuo (~5 Torr). The precipitate that formed
was filtered off and dried at room temperature in vacuo (1 Torr).
[ 2 , 6 ꢀ B i s ( d i p h e n y l p h o s p h o r y l m e t h y l ) ꢀ 4 ꢀ m e t h y l ꢀ
phenolꢀO,O,O]tri(nitratoꢀO,O)aquacerium(III) dihydrate,
[Ce(L2)(NO3)3•(H2O)]•2H2O (2a). The yield was 62%. White
powder. Found (%): C, 43.00; H, 3.75; N, 4.71; P, 6.68.
C33H36CeN3O15P2. Calculated (%): C, 43.24; H, 3.96; N, 4.58;
P, 6.76. The IR spectroscopic data are given in Table 2.
Experiments
All operations, unless otherwise stated, were carried out
under argon. Solvents were saturated with argon, purified,
and dried according to known procedures.10 Potassium metal
of reagent grade (in glass ampoules) was used. The salts
La(NO3)3•6H2O, Ce(NO3)3•6H2O, and Nd(NO3)3•6H2O
(Fisher Scientific Company) were used without additional puriꢀ
fication. The NMR spectra were recorded in deuterated solvents,
viz., CDCl3, CD2Cl2, acetoneꢀd6, and DMSOꢀd6 (Aldrich),
which were also saturated with argon.
The IR spectra were measured in KBr pellets, Nujol or
hexachlorobutadiene mulls, and solutions in CHCl3 and CH2Cl2
at concentrations of 0.02—0.2 mol L–1 on a URꢀ20 spectroꢀ
photometer (in the 400—3700 cm–1 region) with the use of
0.07—0.1 mm cells; the resolution was 5 cm–1. In some cases,
the IR spectra of solid samples and highly dilute solutions were
recorded on a Nicolet Magna IRꢀ750 Fourierꢀtransform specꢀ
trometer; the resolution was 2 cm–1
.
The 1H NMR spectra were measured on a Bruker AMXꢀ400
spectrometer operating at 400.13 MHz at 298 K using residual
protons of the deuterated solvent as the internal standard. Stanꢀ
dard ampoules with a diameter of 5 mm were used. The concenꢀ
trations of the solutions were 0.05 and 0.15 mol L–1
.
The 31P—{1H} NMR spectra were recorded on a Bruker
AMXꢀ400 spectrometer operating at 161.98 MHz at 298 K using
85% H3PO4 as the external standard. Standard ampoules with a
diameter of 5 mm were used. The concentration of solutions was
0.05 mol L–1
.
The ESR spectra were measured on a Bruker EMXꢀ10/12
spectrometer; samples were irradiated in a resonator using a
highꢀpressure mercury lamp (1000 W). Saturated solutions in
anhydrous benzene or a benzene—tertꢀbutyl peroxide mixture
(4 : 1 v/v) were evacuated before measurements.
2,6ꢀBis(diphenylphosphorylmethyl)ꢀ4ꢀmethylphenol (L2) was
prepared by the Arbuzov reaction of 2,6ꢀbis(chloromethyl)ꢀ4ꢀ
methylphenol11 with methyl diphenylphosphinite in refluxing
xylene in 91.0% yield, m.p. 185—186 °C (from benzene),
[2,6ꢀBis(diphenylphosphorylmethyl)ꢀ4ꢀmethylphenolꢀ
O,O,O]tri(nitratoꢀO,O)acetonecerium(III), [Ce(L2)(NO3)3•
•(Me2CO)] (2b) was prepared by the reaction of equimolar
amounts of ligand L2 and the salt Ce(NO3)3•6H2O according to
a procedure described earlier.9 The characteristics of 2b correꢀ
Table 1. 1H and 31P NMR spectroscopic data for phenol L2, its salt 1, and complexes 2b and 3a,c (δ, J/Hz)
Comꢀ
pound
Solvent
1H
31P
OH
(s, 1 H)
Ph
(m, 20 H)
mꢀC6H2
(s, 2 H)
CH2P
(4 H)
Me
(s, 3 H)
L2
1
CD2Cl2
CDCl3
CD2Cl2
CDCl3
CD2Cl2
CD2Cl2
CDCl3
9.90
9.76
—
7.40—7.75
7.35—7.71
7.31—7.73
7.30—7.66
7.70—9.20b
7.50—9.50b
7.24—7.62
6.74
6.76
6.11
3.68 (d, 2JP,H = 13.67)
3.67 (d, 2JP,H = 13.60)
3.72 (d, 2JP,H = 12.75)
3.75 (d, 2JP,H = 12.70)
4.20, br (0.2)c
1.82
2.01
1.68
34.56, s
35.72, s
33.50, s
—
—
—
6.03
1.65
34.30, s
a
2b
3a
3c
5.78 (0.08)c
5.78 (0.07)c
6.20 (0.03)c
1.23 (0.002)c
1.22 (0.003)c
64.4, br.s (4)c
62.8, br.s (4)c
a
4.10, br (0.24)c
a
—
3.70, br (0.26)c
1.68 (0.0008)c 37.72, br.s (0.26)c
a The signal was not recorded.
b A very broad unresolved multiplet.
c The halfꢀwidth of the line ∆1/2 (ppm).

Coordination chemistry of diphosphorylated phenol Russ.Chem.Bull., Int.Ed., Vol. 54, No. 11, November, 2005 2521
Table 2. Main frequencies in the IR spectra (ν/cm–1) of compounds L2 and 1—4a
Comꢀ
pound
Conditions
of spectrum
measurementsa
ν(P=O)
ν(C—O(H))
ν((C)O—H)
ν(N=O) ν (NO2)
ν(H2O)
as
L2
1
KBr
1195, 1150
1185, 1160
1195, 1155
1195
1190, 1175
1151
1151
1152 (br)
1155
1160, 1150
1160
1170, 1155
1160
1250
1250
1250
1470b
1470b
1218
1219
1223
1225
1220
3000
3000
3000
—
—
—
—
—
—
—
—
—
—
—
—
—
CHCl3
CH2Cl2
KBr
CHCl3
KBr
KBr
CHCl3
KBr
CHCl3
KBr
CHCl3
KBr
KBr
KBr
3600—2900
—
—
2a
2b
3200—2600
3200—2600
~3000
3200—2600
3000
1480
1481
1484
1490
1490
1480
1480
1480
1490
1485
1470
1315
1314
1304
1300
1305
1310
1320
1310
1300
1305
1305
3240c
—
—
3a
3b
3500—3400
—
1223
1220
1230
3200—2600
3000
3500—3400
—
3500—3400
3240c
—
3c
3d
4ae
3200—2600
3200—2600, 3380d
3600—2200
3000
1155
1155
1195, 1150, 1140
1235, 1218
1235
1255, 1218
CH2Cl2
—
a The spectra of solid samples were recorded also as Nujol and hexachlorobutadiene mulls.
b
ν(C—O—).
c Coordination water.
d (Et)O—H.
e
E
ν (NO3) = 1350 cm–1
.
spond to the published data. Complex 2b is poorly soluble
in chloroform, dichloromethane, and acetonitrile. The 1H
and 31P NMR and IR spectroscopic parameters are given in
Tables 1 and 2.
[2,6ꢀBis(diphenylphosphorylmethyl)ꢀ4ꢀmethylphenolꢀ
O,O,O][2,6ꢀbis(diphenylphosphorylmethyl)ꢀ4ꢀmethylphenolꢀ
O,O](nitratoꢀO,O)aquacerium(III) dinitrate ethanol solvate,
[Ce(L2)2(H2O)(NO3)]2+•(2NO3–)•EtOH (3d). A weighed
sample of complex 3a (0.0700 g) was dissolved with heating in
ethanol. Colorless crystals that precipitated during storage of the
ethanolic solution were filtered off and dried at room temperaꢀ
ture in vacuo (1—2 Torr), m.p. (with decomp.) 130—135 °C.
The yield was 75%. Virtually colorless transparent crystals suitꢀ
able for Xꢀray diffraction study were obtained. Found (%):
C, 55.61; H, 4.69; N, 2.85. C68H68CeN3O17P4. Calculated (%):
C, 55.81; H, 4.68; N, 2.87. Complex 3d is insoluble in chloroꢀ
form, acetone, and acetonitrile and is poorly soluble in ethanol.
The IR spectroscopic data are given in Table 2.
Bis{2,6ꢀbis(diphenylphosphorylmethyl)ꢀ4ꢀmethylphenolꢀ
O,O,O}tri(nitratoꢀO,O)cerium(III) trihydrate, [Ce(L2)2(NO3)3]•
•3H2O (3a). M.p. (with decomp.) 105—107 °C. The yield was
65%. White powder. Found (%): C, 54.15; H, 4.22; N, 2.91;
P, 8.33. C66H66CeN3O18P4. Calculated (%): C, 54.54; H, 4.58;
N, 2.89; P, 8.52. Complex 3a is soluble in chloroform (readily),
dichloromethane, acetone, and DMSO (with decomposition)
and is poorly soluble in acetonitrile and ethanol (on heating).
The 1H and 31P NMR and IR spectroscopic parameters are
given in Tables 1 and 2.
Bis{2,6ꢀbis(diphenylphosphorylmethyl)ꢀ4ꢀmethylꢀ
Tris{2,6ꢀbis(diphenylphosphorylmethyl)ꢀ4ꢀmethylꢀ
phenolꢀO,O,O}tri(nitratoꢀO,O)neodymium(III)
trihydrate,
phenolꢀO,O}(nitratoꢀO,O)aquacerium(III)
dinitrate,
[Nd(L2)2(NO3)3]•3H2O (3b). M.p. (with decomp.) 115—117 °C.
The yield was 66%. A weakly colored almost white powder with
a paleꢀlilac tint. Found (%): C, 54.09; H, 4.36; N, 2.86; P, 8.38.
C66H66N3NdO18P4. Calculated (%): C, 54.39; H, 4.56; N, 2.88;
P, 8.50. Complex 3b is soluble in chloroform, dichloromethane,
acetone, and DMSO (with decomposition) and poorly soluble
in acetonitrile and ethanol. The IR spectroscopic data are given
in Table 2.
Bis{2,6ꢀbis(diphenylphosphorylmethyl)ꢀ4ꢀmethylꢀ
phenolꢀO,O,O}tri(nitratoꢀO,O)lanthanum(III)
[La(L2)2(NO3)3]•3H2O (3c). The yield was 65%. White
powder. Found (%): C, 54.39; H, 4.46; N, 3.11; P, 8.33.
[Ce(L2)3(NO3)(H2O)]2+(NO3)2 (4a). T.decomp. >95 °C. The
yield was 65%. White powder. Found (%): C, 60.66; H, 4.74;
N, 2.32; P, 9.47. C99H92CeN3O19P6. Calculated (%): C, 60.86;
H, 4.75; N, 2.15; P, 9.51. Complex 4a is soluble in chloroꢀ
form, dichloromethane, acetone, DMSO (with decomposition),
methanol, and ethanol. The IR spectroscopic data are given in
Table 2. 31P—{1H} NMR (CD2Cl2), δ: 64 (∆1/2 = 10 ppm).
Bis{2,6ꢀbis(diphenylphosphorylmethyl)ꢀ4ꢀformylphenolatoꢀ
O,O,O}(nitratoꢀO,O)cerium(III) hemihydrate diacetonitrile solꢀ
vate, [Ce(L3)2(NO3)]•2MeCN•0.5H2O (5a) (L3 = 4ꢀCHOꢀ2,6ꢀ
[Ph2P(O)CH2]2C6H2O–) is one of decomposition products.
Operations were carried out without protection from air.
A weighed sample of phenol L2 (0.1610 g, 0.3 mmol) was disꢀ
solved in CH2Cl2 (3 mL), and a solution of Ce(NO3)3•6H2O
(0.0651 g, 0.15 mmol) in acetonitrile (3 mL) was slowly added
dropwise at ~25 °C. Then anhydrous diethyl ether was added.
trihydrate,
C
66H66LaN3O18P4. Calculated (%): C, 54.59; H, 4.58; N, 2.90;
P, 8.53. Complex 3c is soluble in chloroform, acetone, and
DMSO (with decomposition). The 1H and 31P NMR and
IR spectroscopic parameters are given in Tables 1 and 2.

2522
Russ.Chem.Bull., Int.Ed., Vol. 54, No. 11, November, 2005
Matveeva et al.
The white precipitate that formed was filtered off, washed
with anhydrous diethyl ether, and dried at room temperature
in vacuo (1 Torr). Complex 3a was obtained in a yield of 0.1416 g
(65%). The transparent filtrate was kept without protection
from air for several hours, after which it turned paleꢀblue and
then gradually turned intense blackꢀblue. After storage overꢀ
night, a black inhomogeneous precipitate was obtained, from
which dark crystals were manually separated. The crystals were
purified from the dark powdered precipitate in a mineral oil
under a microscope. Transparent slightly lilac crystals of comꢀ
plex 5a were obtained and characterized by Xꢀray diffraction
analysis.
The unit cell parameters, details of Xꢀray diffraction study,
and parameters of structure refinement are given in Table 3. The
atomic coordinates and displacement parameters were deposꢀ
ited with the Cambridge Structural Database.
Conformational analysis The energy of the complexꢀforming
conformation of the ligand was calculated by the molecular
mechanics method (PC Model, Serena Soft Ware, the MM2
(QCPE 395) and MMP1 (QCPE 318) force fields) with speciꢀ
Table 3. Principal crystallographic data for the comꢀ
plexes [Ce(L2)2(NO3)(H2O)]2+(NO3)2•EtOH (3d) and
[Ce(L3)2(NO3)]•2MeCN•0.5H2O (5a)
Oxidation of complexes 3a—c in solution (general proceꢀ
dure). A weighed sample of complex 3 (0.1 mmol) was dissolved
in CHCl3 (2 mL) without protection from air. After 1 h, the
solution turned blue. After several hours, the solution turned
intense blackꢀblue. After storage overnight, the solution yielded
a black precipitate as a mixture of products (~60% yield; m.p.
(with decomp.) 170—174 °C in the case of 3a or 168—172 °C in
the case of 3b). The IR spectra of the precipitates (Ce and
Nd products) were identical. The spectra were compared with
the spectra of the starting nonoxidized complexes 3a,b. The
spectra of the precipitates (oxidation products) show a band of
coordinated P=O groups at 1145 cm–1 and bands of bidentate
NO3 groups at 1480 and 1300 cm–1. The band of the C—O(H)
group is less intense and is observed at 1233 cm–1, and the
intensity of the C=C band at 1600 cm–1 becomes substantially
higher. Absorption of coordinated (Carom)O—H groups is obꢀ
served at 3420 cm–1, an absorption band of quinoidꢀtype carboꢀ
nyl12 appears at 1685 cm–1, and a band of aldehyde carbonyl is
observed as a shoulder at 1700 cm–1. The spectra show also
mediumꢀ and lowꢀintensity bands at 1060 (absorption of the
C—O(C) group) and 1350 cm–1 (absorption of the coordinated
(Carom)C—O– group). One of oxidation products, viz., comꢀ
plex 5a, was isolated from the mixture (14% by weight) and
characterized by Xꢀray diffraction.
Parameter
3d
5a
Molecular formula C68H68N3CeO17P4 C70H61N3CeO11.5P4
Molecular weight
Space group
T/K
a/Å
b/Å
c/Å
α/deg
β/deg
1463.25
P21/c
110(2)
13.862(2)
21.323(2)
22.488(3)
—
91.696(4)
—
1392.22
C2/c
120(2)
22.7234(4)
15.686(4)
18.626(4)
—
96.989(5)
—
γ/deg
V/Å3
6644(2)
4
1.463
6590(2)
4
1.403
Z
dcalc/g cm–3
Color and habit
of crystals
Crystal
Paleꢀblue
prismatic
0.50×0.30×0.20
Paleꢀgray
plateletꢀlike
0.45×0.35×0.25
dimensions/mm
Diffractometer
Radiation
µ/mm–1
Absorption correction
Tmin/Tmax
Scan mode
2θmax/deg
Total number
of reflections
Number of indeꢀ
pendent
«Bruker SMART»
MoꢀKα (λ = 0.71073 Å)
0.853 0.851
Sadabs
During storage without protection from air, complex 5a,
like a mixture of decomposition products, undergoes further
transformations both in the solid state and in solution.
0.645/0.802
0.665/0.802
φ/ω
48.00
43871
55.10
27641
Xꢀray diffraction study. Crystals of 3d and 5a suitable for
Xꢀray diffraction study were obtained as described above.
Experimental Xꢀray data sets were collected on a Bruker
SMART diffractometer equipped with a CCD area detector
at 110 (3d) and 120 K (5a). The Xꢀray data were processed using
the SAINT 13 and SADABS 14 program packages. The strucꢀ
tures were solved by direct methods. The nonhydrogen atoms
were located from difference electron density maps and refined
anisotropically by the leastꢀsquares method against F 2hkl. The
coordinates of the hydrogen atoms (except for the hydrogen
atoms of the water molecules and OH groups) were calculated
geometrically and refined isotropically using a riding model with
U(H) = 1.2U(C) (for the atoms of the Ph groups) and U(H) =
1.5U(C) (for the atoms of the CH2 groups and the EtOH molꢀ
ecules), where U(C) are the equivalent thermal parameters of
the pivot carbon atoms. The hydrogen atoms of the water molꢀ
ecules and the hydroxy groups were determined from difference
maps and refined isotropically using a riding model with U(H) =
1.5U(O), where U(O) is the equivalent thermal parameter of the
pivot oxygen atom.
9901
(0.0470)
6226
(0.0388)
reflections (Rint
R1 (against F for
reflections with
I > 2σ(I ))
)
0.0472
(6831 отр.)
0.0444
(5068 отр.)
wR2 (against F 2 for
all reflections)
Number of
0.0987
838
0.1050
418
parameters
in refinement
Weighting scheme:
–1 = σ (Fo2) + (aP)2 + bP,
2
w
where P = 1/3(Fo2 + 2Fc
)
2
a
b
0.0236
20.2500
0.986
0.0398
23.106
1.020
0.822/–0.337
GOOF
Electron density
(max/min), e Å–3
F(000)
1.305/–0.469
All calculations were carried out with the use of the
SHELXTL PLUS 5 program package.15
3004
2848

Coordination chemistry of diphosphorylated phenol Russ.Chem.Bull., Int.Ed., Vol. 54, No. 11, November, 2005 2523
fied distances between the atoms involved in coordination. Modꢀ
els of CeIII complexes were constructed with the use of the
corresponding polyhedra and the Ce...O(C) and Ce...O(P) coꢀ
ordination bond lengths (2.66 Å and 2.41 Å, respectively), which
were calculated by averaging the bond lengths determined by
Xꢀray diffraction analysis in the present study and those pubꢀ
lished earlier.9 The strain energy of the conformation (∆E) was
estimated as the difference between the calculated energies of
this conformer and the conformer corresponding to the global
minimum.
dize L2 with PbO2 and 30% H2O2 in organic media failed.
The signal of phenoxide radicals was completely absent
when PbO2 or the tertꢀbutoxide radical, which was generꢀ
ated by photolysis of tertꢀbutyl peroxide in a resonator of
an ESR spectrometer, was used as an oxidizing agent.
Under analogous conditions, the alkyl analog of comꢀ
pound L2, viz., 2,6ꢀdiꢀtertꢀbutylꢀ4ꢀmethylphenol, gave
an intense spectrum of the corresponding radical. Preꢀ
sumably, resistance of L2 to radical oxidation is associꢀ
ated not only with an increase in steric shielding of the
phenoxide radical but also with strong binding of the proꢀ
ton of the OH group to the phosphoryl group.
Results and Discussion
Potassium salt 1, which was prepared by the reaction
of L2 with potassium ethoxide in an ethanolic solution,
was isolated as dihydrate because we failed to remove the
water molecules by vacuum drying over P2O5 at 140 °C
for 4 h. The IR spectra of solid salt 1 show a single band of
free P=O groups at 1195 cm–1. The band of the C—O–
Ligand L2 was synthesized by the Arbuzov reaction of
2,6ꢀbis(chloromethyl)ꢀ4ꢀmethylphenol with ethyl (or
methyl) diphenylphosphinite in refluxing xylene in 91.0%
yield. Earlier,8 this ligand has been prepared in higher
yield (94.5%) by an analogous reaction with the use of
other solvents for the reaction (triglyme) and recrystalliꢀ
zation (ethyl acetate). The melting point of the latter
reaction product is lower (by 10 °C) and the 31P NMR
data (solution in CDCl3) are somewhat different from our
data, although the structure of the resulting phenol was
beyond doubt. The structure of L2 in the solid state and in
solution was not investigated.
The molecule of ligand L2 contains three donor oxyꢀ
gen atoms, which can potentially be involved in comꢀ
plexation. At the same time, the
structure of L2 is favorable for
hydrogen bonding due to the
groups12 of the phenoxide ion is observed at 1470 cm–1
.
The 3660—3680 cm–1 region shows absorption of the waꢀ
ter solvate molecules. In the spectra of solutions of salt 1
in chloroform, absorption of the phosphoryl groups apꢀ
pears at 1190 and 1175 cm–1, which is indicative of coorꢀ
dination of one P=O group to the potassium cation,
another P=O group remaining free. The position of the
band of the C—O– group of the phenoxide ion remains
unchanged, and absorption of water of solvation is absent.
In the solid state, dihydrate of potassium salt 1 exists,
apparently, as the solvated ion pair, in which the potasꢀ
sium cation is coordinated by the oxygen atoms of the
water molecules and the phenoxide group, whereas both
phosphoryl groups remain uncoordinated. In a chloroꢀ
form solution, salt 1 exists as a tight ion pair. The potasꢀ
sium cation is coordinated by two oxygen atoms of the
C—O– and P=O groups resulting in the closure of the sixꢀ
membered chelate ring, and another phosphoryl group
remains free.
presence of two phosphoryl
groups, which are strong proton
acceptors, along with the hyꢀ
droxy group. In the solid state,
related (to ligand L2) phosphoꢀ
rylated phenols, viz., 2ꢀ(diphenylphosphorylmethyl)pheꢀ
nol and 2ꢀ[bis(diphenylphosphoryl)methyl]phenol, are asꢀ
sociated via intermolecular hydrogen bonds.16,17 Unlike
these compounds, molecules L2 in the crystalline state
contain a strong intramolecular O—H...O=P hydrogen
bond (Xꢀray diffraction data), which is retained in soluꢀ
tion (IR spectroscopic data).9
The 31P and 1H NMR spectroscopic data (see Table 1),
which remain virtually unchanged upon dilution (soluꢀ
tions in dichloromethane, chloroform, acetone, and
DMSO), are also consistent with the proposed structure.
Therefore, a strong intramolecular P=O...H—O
hydrogen bond in molecules L2 is retained both in the
solid state and in solution.
In the 1H NMR spectra of solutions of salt 1 in CDCl3
and CD2Cl2, the signals for the protons of the phenoxide
ion are present in the expected region and are shifted
relative to the signals of the free ligand (see Table 1). The
31P NMR spectra of salt 1 in the same solvents (see
Table 1) show one narrow signal due, apparently, to fast
exchange processes. This signal is shifted downfield by
~1 ppm with respect to the signal of the free ligand.
Unlike the starting compound L2, its salt 1 is less
stable to atmospheric oxygen. The color changes both in
solid samples upon storage under ambient conditions and,
more rapidly, in solution (color of the solution gradually
changes from paleꢀyellow to brownꢀorange; new signals
appear in the NMR spectra).
It is known18—20 that the intramolecular hydrogen
bonds in orthoꢀsubstituted phenols, along with the steric
accessibility of the OH group, are among factors responꢀ
sible for stability of these compounds to oxidation by a
radical mechanism.
Complexation
It appeared that compound L2 is extremely stable to
oxidation under homolytic conditions. Attempts to oxiꢀ
In studies of the coordination properties of phenol L2
with respect to lanthanide cations, it was of interest

2524
Russ.Chem.Bull., Int.Ed., Vol. 54, No. 11, November, 2005
Matveeva et al.
to determine the compositions of chelate comꢀ
plexes, which can be formed at different metal : ligand
ratios and establish their structures in the solid state and
in solution.
fact that the 31P NMR spectra of freshly prepared soluꢀ
tions of these complexes are identical to the spectra meaꢀ
sured after prolonged storage of the solutions under an
inert atmosphere. However, the complexes decompose in
coordinatively active media. After dissolution of these
complexes in DMSO, a single signal of the free ligand was
found.
It should be noted that the signals in the 1H and
31P NMR spectra of the cerium(III) and neodymium(III)
complexes are broadened due apparently to the paramagꢀ
netic properties of the cation. The spectra of lanthaꢀ
num(III) complex 3c, which was synthesized for compariꢀ
son, only signals of the CH2 groups are broadened (see
Table 1). The cerium(III) coordination complexes of difꢀ
ferent compositions are characterized by virtually the same
chemical shift (δP ~60), the signal being most broadened
in the spectrum of the trisꢀligand complex. Probably, this
led the authors of the study8 to conclude that complexꢀ
ation of phenol L2 with LnIII affords exclusively monoꢀ
ligand complexes.
In investigations of coordination of the ligand, not
only its dentation but also coordination of the phenol
oxygen atom is of considerable interest. The question is
whether the proton is displaced upon coordination and, if
not, whether the intramolecular hydrogen bond that is
present in the free ligand molecule is retained upon coorꢀ
dination.
Complexes of composition 1 : 1. Complexes with L2 of
composition Ln(L2)(NO3)3•nSolv, where Solv is the solꢀ
vent molecule (water or acetone), are readily formed in
solvents of different polarity with the use of the reagents
in a ratio of 1 : 1. Earlier,9 we have studied and structurꢀ
ally characterized the [Ce(L2)(NO3)3•Me2CO] comꢀ
plex (2b). In this complex, the neutral phenol molecule is
tridentately coordinated. The inner coordination sphere
contains also three bidentate NO3 groups and one acꢀ
etone molecule. The coordination number of the cerium
atom is 10.
Coordination of ligand L2 was studied in the reaction
with cerium(III) nitrate in CH2Cl2 at room temperature
for the molar metal : ligand ratios of 1 : 1, 1 : 2, 1 : 3, and
1 : 4. At the molar ratios L : M = 1, 2, or 3, complexes of
the general formula [Ln(L2)n(NO3)3]•xH2O (n = 1—3)
were obtained. The 31P NMR spectra of solutions show
one broadened signal belonging to the coordinated ligand
in the expected region21 at δ ~60 (in the 31P NMR specꢀ
trum, free ligand is characterized by a singlet at δ 34.56).
In the IR spectra of these solutions, absorption of the
P=O groups of the free ligand is absent.
When the metal : ligand ratio of 1 : 4 was used, one
mole of the ligand remained unconsumed. The 31P NMR
spectra show one broadened signal at δ 47 (∆1/2
=
~15 ppm), which is indicative of fast exchange between
the free ligand and the complex. The IR spectrum of this
solution contains, along with a band of coordinated P=O
groups at 1158 cm–1, a band of free P=O groups at
1195 cm–1 with an intensity ratio of ~(3 : 1) (second
expected band of the free ligand at 1175 cm–1 is not
observed because of overlap with a wing of the band at
1158 cm–1).
Analogous spectral changes were observed in the study
of coordination of the ligand L2 in methanol.
Conformational analysis by the molecular mechanics
method demonstrated that monoꢀ,9 bisꢀ, and trisꢀligand
complexes with the tridentate O,O,Oꢀcoordinated ligands
can be formed. In the bisꢀligand complex, the energy of
complexꢀforming conformations differs from that of the
global maximum by 4.8 kcal mol–1. Coordination of three
ligand molecules to one cerium(III) cation is less favorꢀ
able (but is probable). The strain energies of the complexꢀ
forming conformations for the complex of this composiꢀ
tion is ~4, 5, and 8 kcal mol–1. As in the earlier publicaꢀ
tion,9 the arrangement of the atoms and the interatomic
distances in all the complexes under consideration are
such that the intramolecular P=O...H—O hydrogen bonds
can exist.
The 1 : 1, 1 : 2, and 1 : 3 complexes of L2 with
cerium(III) nitrate and the 1 : 2 complexes of L2 with
neodymium(III) and lanthanum(III) nitrates were isolated
in the individual state and studied in the solid state and in
solution. The structures of the 1 : 1 and 1 : 2 cerium comꢀ
plexes were established by Xꢀray diffraction analysis (see
Ref. 9 and the results of the present study). The IR and
NMR (1H and 31P) spectroscopic data for complexes 2a,b,
3a—d, and 4a are given in Tables 1 and 2, where the
spectroscopic data for ligand L2 and its K salt 1 are preꢀ
sented for comparison.
Note. Hereinafter, the structure in the solid state is referred to as
"solid;" in solution, as "solv." The atoms involved in the interꢀ
molecular hydrogen bond are marked with asterisks.
The complexes with L2 are stable in standard organic
media in the absence of oxygen. This is evident from the

Coordination chemistry of diphosphorylated phenol Russ.Chem.Bull., Int.Ed., Vol. 54, No. 11, November, 2005 2525
The proton of the phenolic hydroxy group is involved
in an intermolecular hydrogen bond with the oxygen atom
of one NO3 group of another molecule of the complex. In
the crystals, the molecules of the complex are linked into
dimers by two such hydrogen bonds.
broadened due to the additional involvement of one P=O
group in the intramolecular hydrogen bond. The band
of the C—O(H) groups of phenol at 1223 cm–1 is indicaꢀ
tive of coordination of the oxygen atom and the involveꢀ
ment of the proton in hydrogen bonding. A broad absorpꢀ
tion band at about 3000 cm–1 characterizes the inꢀ
volvement of the proton of the OH group of phenol in
hydrogen bonding. An analogous bifurcate coordination
of P=O groups has been documented earlier (see, for
example, the study22 and references therein), in particuꢀ
lar, in the CuII complex with cis,cisꢀ1,3,5ꢀtris[2ꢀ(diꢀ
phenylphosphoryl)ethylamino]cyclohexane in aprotic solꢀ
vents. The bands of bidentate NO3 groups are observed at
1484 and 1304 cm–1 (separation is 180 cm–1).23 The band
of the C=O groups of the coordinated acetone ligand, like
that in the spectrum of the crystalline complex, appears at
The IR spectrum of solid complex 2a is virtually idenꢀ
tical to the spectrum9 of crystalline complex 2b except for
absorption bands of the solvent molecules. Instead of abꢀ
sorption of coordinated acetone, the spectrum shows abꢀ
sorption of water solvate molecules (3500—3400 cm–1
and coordinated water molecules (3240 cm–1).
)
The complex of phenol L2 with erbium nitrate
[Er(L2)(NO3)3]Me2CO and the neodymium complex
[Nd(L4)(NO3)3Me2CO]Me2CO, where L4 is the homolog
of L2, viz., 2,6ꢀbis(diphenylphosphorylmethyl)ꢀ4ꢀtertꢀ
butylphenol, have structurally been characterized earlier.8
In both complexes, the neutral phenol ligand exhibits the
O,O,Oꢀcoordination mode, and three nitrate ions are
bidentate. In both structures, the protons of the phenolic
hydroxy groups are involved in intermolecular hydrogen
bonds. In the structure of the ErIII complex, this intermoꢀ
lecular hydrogen bond is formed between the phenolic
hydroxy group and the outerꢀsphere acetone molecule. In
the structure of the NdIII complex, the intermolecular
hydrogen bonds, analogous to those in the structure of
complex 2b, link the molecules into centrosymmetric
dimers.
1700 cm–1
.
1
In the H NMR spectra of solutions of complex 2b in
CD2Cl2, the signal for the phenolic proton is absent due,
apparently, to both paramagnetic broadening and fast exꢀ
change processes. The signals for the other protons are
shifted relative to those of the free ligand and are differꢀ
ently broadened. The signals for the protons of four
Ph groups are most broadened, whereas the signals for the
methyl protons are characterized by the smallest broadꢀ
ening (see Table 1).
The 31P NMR spectrum of complex 2b (see Table 1)
shows one broadened signal shifted upfield with respect to
the signal of the free ligand by ~27 ppm, which is eviꢀ
dence for coordination of one or both P=O groups. The
In chloroform and dichloromethane, the structures of
complexes 2a,b are virtually identical to those in the solid
state,9 with the only exception that the intramolecular
O—H...O=P hydrogen bond exists in solutions instead of
the intermolecular O—H...O—NO2 hydrogen bond that
is present in the solid state.
1
31P and H NMR spectroscopic data, as opposed to the
IR spectroscopic data, did not allow us to make a concluꢀ
sion about coordination of the phenolic OH group in
monoligand complexes 2a,b.
Therefore, coordination of phenol L2 with LnIII niꢀ
trates in solutions, where M : L = 1 : 1, gives rise to
mononuclear chelate complexes, in which the neutral
ligand is tridentate, and three NO3 groups are bidentate.
The complexes are stabilized by the intramolecular
P=O...H—O hydrogen bond.
Complexes of composition 1 : 2. The reactions of pheꢀ
nol L2 with lanthanide nitrates Ln(NO3)3 (Ln = La, Ce,
or Nd) at a metal : ligand ratio of 1 : 2 in lowꢀpolarity
aprotic media gave complexes 3a—c of the general forꢀ
mula Ln(L2)2(NO3)3•3H2O. Unlike monoligand comꢀ
plexes 2a,b, complexes 3a—c are readily soluble in chloꢀ
roform, dichloromethane, acetone, and, on heating, in
ethanol.
The IR spectroscopic data, the 1H and 31P NMR specꢀ
tra (see Tables 1 and 2 and the published data9) comꢀ
plexes 2a,b, and the results of conformational analysis
(molecular mechanics)9 are consistent with the proposed
structures. In the IR spectra of solutions of 2b in chloroꢀ
form and dichloromethane (see Table 2), the band of
coordinated P=O groups is observed at 1152 cm–1 and is
Crystallization of complex 3a from ethanol afforded
crystalline complex 3d of composition Ce(L2)2(NO3)3•
•H2O•EtOH. The structure of 3d was established by Xꢀ
ray diffraction. The structure of complex 3d contains the
–
complex cations [Ce(L2)2(NO3)(H2O)]2+, the NO3 anꢀ
ions and the EtOH solvate molecules linked by hydrogen
bonds (Figs 1 and 2).

2526
Russ.Chem.Bull., Int.Ed., Vol. 54, No. 11, November, 2005
Matveeva et al.
Ph
Ph
H(1AA)
O(1A)
P(2)
C(7A)
O(3)
C(8)
C(6)
C(2A)
Ph
C(3A)
C(4A)
C(5A)
C(1A)
C(5)
C(4)
P(1A)
O(1W)
C(33A)
C(6A)
C(8A)
C(33)
Ce(1)
C(1)
Ph
Ph
O(2A)
O(1)
H(1A)
P(2A)
C(3)
O(2)
O(3A)
O(4)
N(1)
C(2)
Ph
Ph
P(1)
C(7)
O(5)
Ph
O(6)
Fig. 1. Structure of the [Ce(L2)2(NO3)(H2O)]2+ cation in complex 3d. The phenyl rings in the P(O)Ph2 groups are denoted as Ph.
The coordination polyhedron {CeO8} is formed by
eight oxygen atoms, five of which belong to two indepenꢀ
dent molecules of ligand L2, two atoms belong to the
bidentate nitrate ion, and one oxygen atom belongs to the
water molecule. Assuming that the bidentate NO3– anion
occupies one coordination site (X), the coordination polyꢀ
hedron of the cerium atom in the [Ce(L2)2(NO3)(H2O)]2+
cation can be represented as a distorted octahedron, whose
upper faces are formed by the O(1), O(3), and O(3A)
atoms and O(2), O(2A), and X (X is the midpoint of the
distance between the O(4) and O(5) atoms of the NO3
anion). These faces are noncoplanar, the dihedral angle
–
O(1S)
H(1SA)
O(8)
N(2)
O(7)
O(9)
O(10)
O(11)
Ph
N(3)
O(10)
H(2W1)
H(1W1)
O(1W)
H(1A)
Ph
Ph
O(1)
P(2A)
O(3A)
O(1A)
H(1AA)
O(5)
C(1)
P(2)
Ce(1)
C(1A)
O(6)
N(1)
O(3)
Ph
O(4)
O(2)
Ph
P(1)
O(2A)
P(1A)
Ph
Ph
Ph
Fig. 2. Structure of complex 3d. The phenyl rings in the P(O)Ph2 groups are denoted as Ph.

Coordination chemistry of diphosphorylated phenol Russ.Chem.Bull., Int.Ed., Vol. 54, No. 11, November, 2005 2527
between the faces is 12.8°, and the Ce atom is at different
distances from two faces (0.74 and 1.52 Å). The former
face is centered by the water molecule, which is located at
a distance of 1.80 Å from this plane.
gen bonds. The ethanol solvate molecule is held in the
outer coordination sphere by a hydrogen bond with the
nitrate ion. The main bond lengths and bond angles are
given in Table 4.
The bonds between the cerium atom and the oxygen
atoms of two ligand molecules in the cation differ in
length. The distances between the cerium atom and the
phosphoryl oxygen atoms, Ce—O(P), in one ligand molꢀ
ecule (A) are rather similar to each other (Ce(1)—O(2),
2.437(3) Å; Ce(1)—O(3), 2.461(3) Å; ∆d = 0.24 Å),
whereas these distances in another ligand molecule (B)
are substantially different (Ce(1)—O(2A), 2.363(3) Å
and Ce(1)—O(3A) 2.413(3) Å; ∆d = 0.50 Å). The bond
between the Ce atom and the phenol oxygen atom of
one ligand molecule (Ce(1)—O(1), 2.590(3) Å) is subꢀ
stantially shorter than the Ce(1)...O(1A) distance
(2.937(3) Å), although the HO—C(Ar) bonds are equal in
length (aver., 1.393 Å) and are elongated compared to the
standard24 uncoordinated Ar—OH bonds (1.367 Å). The
Ce(1)...O(1A) distance is so large that it cannot be conꢀ
sidered as a bond. Therefore, one molecule L2 in the
complex cation is tridentate, and another molecule is
only bidentate.
In the spectrum of crystalline complex 3d, the band of
the coordinated P=O groups is observed at 1155 cm–1
.
Two bands at 1218 and 1235 cm–1 correspond to the
coordinated and free C—O(H) groups, the hydrogen
atoms of both groups being involved in hydrogen bondꢀ
ing. The spectrum shows also bands of the NO3 groups at
1490 and 1300 cm–1. These bands are attributed to abꢀ
sorption of two types of bidentate NO3 ions (ions coordiꢀ
nated to the metal cation in a chelate fashion and bridging
ions, which are involved in a tight ion pair and form two
strong hydrogen bonds each) because both types of speꢀ
cies have the same symmetry. In the OH vibration region,
absorption at 3200—2600 cm–1 corresponds to vibrations
of the phenolic hydroxy group involved in hydrogen bondꢀ
ing. The band at ~3240 cm–1 belongs to the coordinated
water molecule, and the band at 3380 cm–1 is assigned to
the OH groups of the ethanol solvate molecules. The
spectra of solutions of complex 3d were not recorded
because crystals of 3d are insoluble in chloroform, acetoꢀ
nitrile, and acetone and are poorly soluble in ethanol.
The spectra of the solid complexes Ln(L2)2(NO3)3•
•3H2O (3a—c) are virtually identical to each other and
differ only slightly from the spectrum of crystalline comꢀ
plex 3d. The spectra of complexes 3a—c show broad abꢀ
In both ligand molecules, the phenol fragments
4ꢀMeꢀ2,6ꢀ(CH2)2ꢀC6H2O are planar (average deviations
of the atoms from the plane are 0.069 and 0.032 Å for
the molecules containing the O(1) and O(1A) atoms, reꢀ
spectively) and are almost orthogonal to each other (diꢀ
hedral angle between the planes is 79.0°).
sorption in the OH vibration region at 3200—2600 cm–1
,
–
The uncoordinated NO3 anions are held near the
which is indicative of the involvement of the phenolic
hydroxy group in hydrogen bonding. This region contains
also a weak band at 3500—3400 cm–1, which can be asꢀ
signed to the outerꢀsphere water molecules. Absorption of
the P=O groups appears as one rather narrow band
at 1155—1160 cm–1, which is indicative of coordinaꢀ
tion and equivalence of the phosphoryl groups of both
ligand molecules. The bands of the C—O(H) groups at
1223—1230 cm–1 are also shifted to lower frequencies
with respect to the bands of the free ligand (see Table 2),
which is evidence that these groups are involved in comꢀ
plexation. Intense bands of the coordinated NO3 groups
are observed at 1480—1490 and 1300—1310 cm–1 (see
cation by hydrogen bonds with the coordinated waꢀ
ter molecule and the OH groups of both ligand molꢀ
ecules (Fig. 2). These hydrogen bonds, O—H...O(NO2)
and Ow—H...O(NO2), belong to strong O—H...O and
Ow—H...O bonds (particularly, the O(1)—H(1A)...O(7)
bond; the O(1)...O(7) distance (2.631(4) Å) is much
shorter than the other O...O distances (O(1A)...O(10),
2.708(4) Å; O(1W)...O(11), 2.731(4) Å; O(1W)...O(9),
2.746(4) Å); the H...O distances are 1.80—1.96 Å). The
hydrogen atoms of the OH groups in both ligand molꢀ
ecules are not involved in intramolecular shortened conꢀ
tacts with the oxygen atoms of the P=O groups (all
H...O(P) distances are longer than 3.5 Å). Both ligand
molecules have identical contacts between the oxygen
atoms of the OH and P=O groups within the cations, in
spite of the fact that the O(1A) atom is not coordinated to
the cerium atom. The O(1)...O(2) and O(1)...O(3) disꢀ
tances in one ligand molecule are 2.942 and 3.020 Å, and
the analogous distances in another molecule are 2.940
and 2.999 Å, respectively.
Table 2). The separation between the bands is ~190 cm–1
,
which is consistent with the bidentate coordination.23 The
NO3 groups are most probably coordinated to the LnIII
cation in a chelate fashion.*
Analysis of the IR spectra shows that both ligand molꢀ
ecules in solid bisꢀligand complexes 3a—c exhibit the
maximum O,O,Oꢀcoordination due to the involvement of
* Complexes 3a—c lose solubility in aprotic solvents upon storꢀ
age. In the IR spectra, a weak band of coordinated water appears
in the region of OH vibrations at 3300—3200 cm–1; the positions
of other bands remain unchanged. Presumably, the structures of
complexes 3a—c change with time and become similar to the
structure of crystalline complex 3d.
Therefore, the structure of complex 3d is composed of
–
isolated cationꢀanion pairs, in which two NO3 anions
are held near the doubly charged cation thus compensatꢀ
ing its charge. In addition to Coulombic interactions beꢀ
tween the counterions, the structure is stabilized by hydroꢀ

2528
Russ.Chem.Bull., Int.Ed., Vol. 54, No. 11, November, 2005
Matveeva et al.
Table 4. Selected bond lengths, interatomic distances (d), and bond angles (ω) in the [Ce(L2)2(NO3)(H2O)]2+ cation (complex 3d)
and the [Ce(L3)2(NO3)] molecule (complex 5a)
Parameter
Value
Parameter
Value
3d
5a
3d
5a
Bond,
d/Å
Angle
ω/deg
distance
A
B
A
B
Ce(1)—O(1)
Ce(1)—O(2)
Ce(1)—O(3)
Ce(1)—O(4)
Ce(1)—O(5)
Ce(1)—O(1W)
P(1)—O(2)
P(2)—O(3)
P(1)—C(7)
P(1)—C(9)
P(1)—C(15)
P(2)—C(8)
P(2)—C(21)
P(2)—C(27)
O(1)—C(1)
C(1)—C(6)
C(1)—C(2)
C(2)—C(3)
C(2)—C(7)
C(3)—C(4)
C(4)—C(5)
C(4)—C(33)
C(5)—C(6)
C(6)—C(8)
N(1)—O(4)
N(1)—O(5)
N(1)—O(6)
O(1)...O(7)
O(1A)...O(10)
2.590(3) 2.937(3)
2.437(3) 2.363(3)
2.461(3) 2.413(3)
2.636(3)
2.575(3)
2.565(3)
2.374(3)
2.497(3)
2.433(2)
2.605(3)
—
O(1)—Ce(1)—O(1A)
O(1)—Ce(1)—O(2)
O(1)—Ce(1)—O(3)
O(1)—Ce(1)—O(4)
O(1)—Ce(1)—O(5)
O(1)—Ce(1)—O(1W)
O(1A)—Ce(1)—O(2A) 66.07(9)
O(1A)—Ce(1)—O(3A) 67.36(9)
O(1A)—Ce(1)—O(4)
O(1A)—Ce(1)—O(5)
134.19(9)
71.4(1)
73.35(9)
112.6(1)
67.1(1)
76.2(1)
71.96(9)
76.83(8)
132.71(8)
—
—
67.36(9)
—
1.517(3) 1.502(3)
1.506(3) 1.496(3)
1.838(5) 1.811(4)
1.803(5) 1.802(5)
1.800(5) 1.809(5)
1.830(5) 1.815(5)
1.804(5) 1.811(5)
1.806(5) 1.806(5)
1.394(5) 1.392(5)
1.385(7) 1.412(6)
1.408(6) 1.407(6)
1.406(6) 1.383(6)
1.492(7) 1.503(6)
1.393(7) 1.395(7)
1.376(7) 1.389(7)
1.506(7) 1.504(7)
1.402(6) 1.390(6)
1.523(6) 1.516(6)
1.265(5)
1.485(3)
1.508(3)
1.812(4)
1.815(4)
1.797(4)
1.814(4)
1.795(4)
1.803(4)
1.302(4)
1.437(5)
1.413(5)
1.379(5)
1.506(5)
1.396(5)
1.374(6)
1.445(5)
1.368(5)
1.507(5)
1.254(3)
—
71.96(9)
76.83(8)
132.71(8)
—
109.40(9)
137.80(9)
O(1A)—Ce(1)—O(1W) 70.04(9)
—
O(2)—Ce(1)—O(2A)
O(3)—Ce(1)—O(3A)
P(1)—O(2)—Ce(1)
P(2)—O(3)—Ce(1)
C(1)—O(1)—Ce(1)
С(1)—C(2)—C(7)
С(1)—C(6)—C(8)
С(2)—C(7)—Р(1)
С(6)—C(8)—Р(2)
С(7)—Р(1)—O(2)
С(8)—Р(2)—O(3)
77.7(1)
139.4(1)
140.6(1)
153.7(1)
146.1(2)
133.4(1)
138.0(2)
118.2(3)
118.0(3)
114.6(3)
109.7(3)
114.8(2)
113.2(2)
141.6(2) 162.9(2)
146.6(2) 161.2(2)
130.7(2) 121.1(2)
121.2(4) 119.8(4)
120.1(4) 121.4(4)
108.6(3) 111.0(3)
108.7(3) 108.2(3)
111.6(2) 112.0(2)
113.6(2) 111.3(2)
1.303(5)
1.207(5)
2.627(5)
2.707(5)
1.238(6)
—
—
Note: A is the tridentate molecule, and B is a bidentate molecule.
two P=O groups and one C—O(H) group giving rise to
two sevenꢀmembered rings. The protons of the phenolic
hydroxy groups are involved in intermolecular hydrogen
bonds. It is highly probable that three NO3 groups are
coordinated to the central cation in a chelate fashion.
If this is the case, the coordination number of the
lanthanide(III) cation is 12, and the structures of the neuꢀ
tral complexes [Ln(L2)2(NO3)3]•3H2O can be represented
as follows.
In solutions, the structures of the complexes are, on
the whole, retained. In the IR spectra of solutions of the
bisꢀligand complexes in chloroform, only slight changes
are observed in the bands of the functional C—O(H) and
NO3 groups. A new broad band with a maximum at
3000 cm–1 appears in the spectrum, which corresponds to
vibrations of the phenolic OH groups involved in hydroꢀ
gen bonding. The band of the outerꢀsphere water molꢀ
ecules disappears. The band of the coordinated P=O
groups appears as a doublet (see Table 2). These spectral
changes can be attributed to the fact that one P=O group
(at 1140—1155 cm–1) is involved not only in coordinaꢀ
tion to metal but also in additional intramolecular hydroꢀ
gen bonding with the phenolic hydroxy group.
The coordination number of the lanthanide cation in
complexes 3a—c is 12.
The 1H and 31P NMR spectroscopic parameters of
solutions of bisꢀligand complex 3a are similar to those of
monoligand complex 2b (see Table 1), do not contradict
the proposed structure, and suggest that the ligand in
these complexes exhibits a similar coordination mode.
A fine structure is absent from the spectra. The observed
broadening of the signals is associated primarily with the
paramagnetic properties of the cations in the complexes.
As in the case of the monoligand complexes, the strucꢀ
tures of bisꢀligand complexes 3a—c in the solid state difꢀ
fer from those in solution primarily in that the intramoꢀ

Coordination chemistry of diphosphorylated phenol Russ.Chem.Bull., Int.Ed., Vol. 54, No. 11, November, 2005 2529
with complex 3d. The unit cell parameters of 3e are virtuꢀ
ally identical to those of complex 3d, which was preꢀ
pared from an ethanolic solution with the use of the
metal : ligand ratio of 1 : 2 and was characterized in the
present study.
In the IR spectrum of solid complex 4a, the band of
free P=O groups is absent, and a single band of the P=O
groups is observed at 1155 cm–1, which indicates that all
coordinated P=O groups in this complex are equivalent
and are not involved in additional interactions. The
C—O(H) group is characterized by one band at 1235 cm–1
,
which (based on analysis of the data for structurally charꢀ
acterized complex 3d) can be assigned to vibrations of the
uncoordinated phenol group, whose hydrogen atom is
involved in hydrogen bonding. Therefore, all three ligand
molecules are coordinated in a bidentate fashion. The
bands of the NO3 groups are observed at 1485 and
1305 cm–1, which is evidence that they are bidentate.23
Very broad absorption at 3600—2200 cm–1 in the OH
vibration region includes, apparently, vibrations of the
phenolic OH groups and the OH groups of water molꢀ
ecules involved in hydrogen bonding.
The elemental analysis data and the IR spectra for
compound 4a suggest that this compound, most probꢀ
ably, has the structure of the cationic complex
[Ce(L2)3(NO3)(H2O)]2+•2NO3–, in which the ligand is
bidentate due to the involvement of both P=O groups in
coordination. The inner sphere of the cation contains one
water molecule and one chelate NO3 group. The protons
of the OH groups of the coordinated ligand and water
molecules form hydrogen bonds with the oxygen atoms of
two outerꢀsphere NO3 groups due to which these bridging
groups manifest themselves in the spectra like the innerꢀ
sphere chelate NO3 group. The coordination number of
cerium in this complex is 9.
Ln = Ce (a), Nd (b), La (c)
lecular P=O...H—O hydrogen bonds are present in soluꢀ
tion instead of intermolecular hydrogen bonds involving
the same HO groups found in the crystals.
Complexes of composition 1 : 3. As mentioned above,
the reaction of cerium nitrate with the ligand in dichloroꢀ
methane or methanol in a ratio of 1 : 3 and 1 : 4 affords
the trisꢀligand complex. The Ce(L2)3(NO3)3•2H2O comꢀ
plex (4a) was isolated in the solid state. It is soluble in
chloroform, dichloromethane, and methanol.
Attempts to isolate the crystalline 1 : 3 complex suitꢀ
able for Xꢀray diffraction study failed. The 1 : 2 complex
crystallized from methanol even when the metal : ligand
ratio of 1 : 4 was used. According to the preliminary Xꢀray
diffraction data, monoclinic crystals of this complex,
[Ce(L2)2(NO3)(H2O)](NO3)2•MeOH (3e), are isotypic
–
•2 NO3

2530
Russ.Chem.Bull., Int.Ed., Vol. 54, No. 11, November, 2005
Matveeva et al.
In the IR spectrum of a solution of complex 4a in
dichloromethane, changes in the bands of the functional
groups are observed. Vibrations of the phosphoryl groups
appear as a narrow band at 1195 cm–1 and a poorly reꢀ
solved broadened doublet at 1150 and 1140 cm–1 with an
intensity ratio is ~1 : ~4 : ~4. Vibrations of C—O(H)
groups are observed as two bands at 1255 and 1218 cm–1
with an intensity ratio of ~1 : ~4. In addition to the bands
of the bidentate NO3 groups at 1470 and 1305 cm–1, a
band of free NO3 groups appears at 1350 cm–1. The specꢀ
trum also shows a broad pronounced band with a maxiꢀ
mum at 3000 cm–1 corresponding to vibrations of the OH
groups of the phenol and water molecules involved in
hydrogen bonding.
–
•2 NO3
These spectral changes can be attributed to partial
dissociation of the trisꢀligand complex giving rise to the
free ligand and the bisꢀligand complex:
[Ce(L2)3(NO3)(H2O)] + 2 NO3
In solution, this complex is unstable and exists in equiꢀ
librium with the corresponding bisꢀligand cerium comꢀ
plex and the free ligand.
[Ce(L2)2(NO3)3] + L2.
(1)
According to the equilibrium (1), the observed specꢀ
tral pattern is a superposition of the spectra of three speꢀ
cies, viz., the trisꢀligand complex with outerꢀsphere (free)
NO3 groups, the bisꢀligand complex, and the free ligand.
The trisꢀligand complex is characterized by two absorpꢀ
Unlike complex 4a, the trisꢀligand complex, which
was prepared without isolation in a solution by the reacꢀ
tion of 1 mole of Ce(NO3)3•6H2O with 3 moles of ligand
L2 and, as a consequence, in a solvent containing ~0.2 M
H2O, is stable. The IR and NMR spectra show no eviꢀ
dence for the free ligand. Bands of the free ligand appear
only after the addition of the fourth mole of phenol L2.
The 31P NMR spectrum of a solution of 1 mole of
Ce(NO3)3•6H2O and 3 moles of ligand L2 in dichloroꢀ
tion bands of the P=O groups at 1150 and 1140 cm–1
,
which (as in the aboveꢀconsidered cases) can be interꢀ
preted as absorption of the coordinated P=O groups, one
of which is involved in an intramolecular hydrogen bond
with the OH group of the ligand. The phosphoryl groups
of the free ligand are characterized by bands at 1195 and
1155 cm–1, and absorption of the P=O groups of the bisꢀ
ligand complex in dichloromethane appears at 1155 and
1145 cm–1. In both complexes, the band of the coordiꢀ
nated C—O(H) group involved in the hydrogen bond is
observed at 1218 cm–1, whereas the band of this group in
the free ligand appears at 1255 cm–1. The observed intenꢀ
sities of the bands of the free and bidentate NO3 groups
suggest that one NO3 group in the trisꢀligand complex, as
opposed to the bisꢀligand complex, is coordinated to the
cation in a chelate fashion, whereas two other NO3 groups
(which are observed in the spectra as free groups) are held
in the outer sphere of the complex by nonspecific Couꢀ
lombic interactions. Therefore, the structure of complex
4a in the solid state differs from that in an aprotic solꢀ
vent, although the composition of the complex cation
[Ce(L2)3(NO3)(H2O)]2+ remains unchanged. In solutions,
the ligand molecules are tridentate and the phenolic OH
groups are involved in intramolecular hydrogen bonds, as
opposed to the complex in the solid state, where the ligand
molecules are bidentate and the phenolic OH groups are
involved in intermolecular hydrogen bonds. The coordiꢀ
nation number of cerium is 12.
methane shows one broadened signal at δ 64 (∆1/2
10 ppm). In the IR spectrum of this solution, the band of
the coordinated P=O groups is observed at 1155 cm–1
=
,
and the C—O(H) groups are characterized by one band
at 1125 cm–1. According to the above analysis, the latter
band should be assigned to vibrations of the coordinated
C—O(H) group, whose proton is involved simultaneously
in a hydrogen bond. A broad clear band with a maximum
at 3000 cm–1 corresponds to vibrations of the phenolic
hydroxy group involved in hydrogen bonding. The band
of coordinated water is observed at 3400 cm–1, and the
bands at 3680 and 3660 cm–1 correspond to free water
(introduced into the solution together with Ce(NO3)3•
•6H2O). Intense bands of the NO3 groups appear at 1480
and 1305 cm–1, which indicates that these groups are
bidentate (groups coordinated to the cation in a chelate
fashion and/or bridging groups, each being involved in
two hydrogen bonds with the OH groups of the coordiꢀ
nated ligand and water molecules). Apparently, the comꢀ
plex has the composition Ce(L2)3(NO3)3(H2O)n, where
n = 2 or 3, in solution. Assuming that the coordination
number of the cerium(III) atom in this complex is 12
(many lanthanide complexes, including cerium comꢀ
plexes, with this coordination number were docuꢀ

Coordination chemistry of diphosphorylated phenol Russ.Chem.Bull., Int.Ed., Vol. 54, No. 11, November, 2005 2531
mented25), the structure of the complex can be repreꢀ
The proton of the phenolic hydroxy group is involved in
intraꢀ or intermolecular hydrogen bonding.
–
sented by the formula [Ce(L2)3(H2O)3]3+•3NO3
.
Stability to oxidation with atmospheric oxygen
We demonstrated that phenol L2 is very stable to radiꢀ
cal oxidation compared to other sterically hindered
phenols due in part to stabilization of the molecule by a
strong intramolecular hydrogen bond.
However, the ligand is readily oxidized with atmoꢀ
spheric oxygen upon coordination with lanthanide niꢀ
trates. In the complexes under study, easy innerꢀsphere
oxidation of the ligand with atmospheric oxygen occurs.
The structure of one of the oxidation products (complex
5a) was established by Xꢀray diffraction. According to the
results of IR spectroscopy, quinoidꢀlike compounds are
present, along with salt 5a (~14%), as the main compoꢀ
nents in a nonseparable mixture.
The structure of complex (chelate salt) 5a consists of
the neutral [Ce(L3)2(NO3)] molecules containing two
deprotonated ligands (phenoxide anions) (L3 = 4ꢀCHOꢀ
–
2,6ꢀ[Ph2P(O)CH2]2C6H2O–) and one NO3 ion. The
Three outerꢀsphere NO3 ions in low polarity solvents,
which cannot be involved in solvation through hydrogen
bonds (in the case under consideration, dichloromethane),
form a tight ion pair with the complex cation. In this pair,
the counterions can be held together not only by Couꢀ
lombic forces but also by hydrogen bonds with the innerꢀ
sphere coordinated groups; the latter bonds can be very
strong (see, for example, Xꢀray diffraction data for comꢀ
plex 3d). Six P=O groups are coordinated to the cation.
All three neutral ligands L2 are tridentate. The protons of
the phenolic hydroxy groups and the coordinated water
molecules are involved in intermolecular hydrogen bonds
with the outerꢀsphere NO3 groups. The spectroscopic
characteristics of these NO3 groups (two oxygen atoms of
each group are involved in hydrogen bonding) are analoꢀ
gous to those of the groups coordinated to the metal catꢀ
ion in a bidentate fashion.26
crystal structure contains also acetonitrile and water solꢀ
vate molecules. The oxygen atom of the CHO substituent
is disordered over two positions (O(6) and O(6A)) with
equal occupancies, which corresponds to the twist of the
substituent relative to the ring by 180°. The molecular
structure of the [Ce(L3)2(NO3)] complex 5a is shown
in Fig. 3.
The [Ce(L3)2(NO3)] molecule in the structure of 5a
lies on a twofold axis. The coordination polyhedron
{CeO8} is formed by the oxygen atoms of the P=O groups,
the atoms of the deprotonated hydroxy groups of two
ligands L3, and the bidentate NO3 group. The polyhedron
can be described as a distorted pentagonal bipyramid
whose base is formed by the O(1), O(2), O(1A), and
O(2A) atoms and the point X (X is the midpoint between
the O(4) and O(4A) atoms of the coordinated NO3 group);
the apices of the bipyramid are occupied by the O(3) and
O(3A) atoms. The O(3A)—Ce(1)—O(3A) angle is 153.7°,
and the NO3 group is orthogonal to the base of the
bipyramid.
Conformational analysis (molecular mechanics)
showed that the formation of complexes of composition
L : M = 3 : 1 is quite probable.
The formation of complexes with transition metal catꢀ
ions (CoII and CuII), in which L : M = 3 : 1, in solution
was documented27 also for compound L1 (R = Ph), which
is a prototype of phenol L2 having the same ligand conꢀ
tour (1 : 1 and 2 : 1 complexes are formed at other L : M
ratios).
Therefore, the reaction of L2 with cerium(III) nitrate
in nonpolar aprotic solvents gives complexes containing
the ligand and metal in a ratio of 1 : 1, 2 : 1, or 3 : 1
depending on the ratio of the starting components. In the
complexes, the neutral ligand exhibits variable dentation.
Unlike the phosphoryl oxygen atoms, the oxygen atom of
the hydroxy group is not always involved in coordination.
The Ce—O(Ar) bond lengths in the [Ce(L3)2(NO3)]
molecule are substantially shorter than the Ce—O(H)(Ar)
bonds in the [Ce(L2)2(NO3)(H2O)]2+ cation (see Table 4),
which is reasonable because ligand L3 in compound 5a is
an anion, whereas ligand L2 in 3d is a neutral molecule.
The Ce—O(P) bonds in 5a are longer than those in 3d,
but they also differ substantially from each other
(∆d = 0.64 Å).
The central phenol ring C(1)—C(6) in the
[Ce(L3)2(NO3)] molecule is characterized by a certain
contribution of the quinoid form, unlike the ring in the
[Ce(L2)2(NO3)(H2O)]2+ cation. In the structure of 5a,
the C(2)—C(3) and C(5)—C(6) bonds in the central

2532
Russ.Chem.Bull., Int.Ed., Vol. 54, No. 11, November, 2005
Matveeva et al.
O(6A)
O(6)
C(33)
C(4)
C(3)
C(2)
C(7)
Ph
P(2A)
C(5)
C(1)
P(1)
O(2)
C(6)
Ph
C(8)
O(1)
O(3A)
O(1A)
Ce(1)
P(2)
O(3)
Ph
O(4A)
O(2A)
O(4)
Ph
N(1)
O(5)
P(1A)
Fig. 3. Structure of the [Ce(L3)2(NO3)] molecule. The phenyl rings in the P(O)Ph2 groups are denoted as Ph.
ring are shorter (aver., 1.373 Å) than the other bonds
(aver., 1.405 Å). The C(4)—C(33) and C(1)—O(1)
bonds are also shorter than the analogous bonds in the
[Ce(L2)2(NO3)(H2O)]2+ cation, where the ring has a
standard benzoid structure, and than the standard C—O
and C(Ph)—C(sp2) bonds in enols (1.333 and 1.483 Å,
respectively24). Apparently, this difference is due to
deprotonation of the hydroxy group and the mesomeric
effect of the formyl substituent in ligand L3. Since phenol
HL3 should be a much stronger acid than phenol L2,
its coordination to the lanthanide cation can be accomꢀ
panied by the displacement of the proton to form cheꢀ
late salt 5a. For example, the acidity of the analog of
2,6ꢀdiꢀtertꢀbutylꢀ4ꢀmethylphenol containing the CHO
group instead of the methyl group in the para position of
the phenol ring increases by more than four orders of
magnitude.28
The phenol fragments 4ꢀMeꢀ2,6ꢀ(CH2)2C6H2O, like
those in complex 3d, are planar (average deviation of the
atoms is (0.032—0.069) Å) and are almost orthogonal
with respect to each other (dihedral angle between the
planes is 85°).
A comparison of the structures of 3d and 5a shows
that the molecules differ in the twist of the Ph2P=O groups
with respect to the P—CH2 bond, although the geometric
parameters of the O=P—CH2—C6H2(O)—CH2—P=O
moieties of ligands L2 in complex 3d are similar to those
of ligands L3 in complex 5a (C(Ar)—CH2, P—CH2, and
P=O bond lengths and the corresponding bond angles,
see Table 4). For example, the deviations of the O(2)
and O(3) atoms in complex 3d from the plane of the
C6H2O(CH2)2 fragment in both molecules of coordinated
neutral ligand L2 are nearly equal (2.235(5) and 2.247(5) Å
in one molecule and 2.190(5) and 2.309(5) Å in another
molecule). In chelate salt 5a, these deviations are subꢀ
stantially different (1.730(5) and 2.284(4) Å, respecꢀ
tively). Presumably, this difference in the conformaꢀ
tion of the coordinated ligands is associated with steric
factors caused by "contraction" of the coordination polyꢀ
hedron of the cerium atom in the [Ce(L3)2(NO3)] molꢀ
ecule due to formation of the stronger Ce—O(1) bonds
and the absence of coordinated water molecules. The
molecular packing in the structure of 5a, unlike that in 3d,
is determined only by van der Waals interatomic interꢀ
actions.
The formation of salt 5a as one of oxidation products
agrees well with the known data on catalytic oxidation of
sterically hindered phenols with atmospheric oxygen.28
For example, oxidation of 4ꢀmethylꢀ2,6ꢀdiꢀtertꢀbutylꢀ
phenol in the presence of amines and copper salts affords
a complex mixture of compounds, from which several
quinoidꢀlike compounds (main component was obtained
in ~50% yield) and 4ꢀhydroxyꢀ3,5ꢀdiꢀtertꢀbutylbenzꢀ
aldehyde (~12%) were isolated.29 The fact that oxidation
products of phenols L2 are structurally similar to oxidaꢀ
tion products of the alkyl analog of L2 suggests that innerꢀ
sphere oxidation of the coordinated phenol occurs in both
cases.
Oxidation of sterically hindered phenols with atmoꢀ
spheric oxygen, which is a typical radical reaction, has

Coordination chemistry of diphosphorylated phenol Russ.Chem.Bull., Int.Ed., Vol. 54, No. 11, November, 2005 2533
been studied inꢀdepth.28 In the absence of catalysts, exꢀ
2. M. K. Chmutova, N. E. Kochetkova, and B. F. Myasoedov,
J. Inorg. Nucl. Chem., 1980, 42, 897.
3. G. V. Bodrin, M. I. Kabachnik, N. E. Kochetkova, T. Ya.
Medved´, B. F. Myasoedov, Yu. M. Polikarpov, and M. K.
Chmutova, Izv. Akad. Nauk, Ser. Khim., 1984, 1841 [Bull.
Acad. Sci. USSR, Div. Chem. Sci., 1984, 33, 1682 (Engl.
Transl.)].
4. B. F. Myasoedov, G. V. Bodrin, M. K. Chmutova,
tensive oxidation of sterically hindered phenols with oxyꢀ
gen is possible in an alkaline medium only. In this case,
the reaction involves the phenoxide ion, the electron transꢀ
fer from which to an oxidizing agent occurs more easily
than from the neutral phenol molecule.28 Potassium salt 1
is less resistant to atmospheric oxygen than the starting
phenol L2.
Apparently, oxidation of both phenols proceeds by the
N. E. Kochetkova, T. Ya. Medved´, Yu. M. Polikarpov,
and M. I. Kabachnik, Solvent Extr. Ion Exch., 1983,
1, 689.WW
5. E. I. Matrosov, M. Yu. Antipin, A. G. Matveeva, A. P.
Baranov, G. V. Bodrin, Yu. M. Polikarpov, Yu. T. Struchkov,
and M. I. Kabachnik, Dokl. Akad. Nauk SSSR, 1989, 309,
140 [Dokl. Chem., 1989 (Engl. Transl.)].
6. M. I. Kabachnik, Heteroatom. Chem., 1991, 2, 1.
7. A. G. Matveeva, E. I. Matrosov, Z. A. Starikova, G. V.
Bodrin, S. V. Matveev, V. P. Morgalyuk, I. G. Tananaev,
B. F. Myasoedov, and E. E. Nifant´ev, Abstr., XIV Conf. on
Chemistry of Phosphorus Compounds (Kazan, June 27—July 1,
2005), Russia, 2005, p. 91.
8. R. T. Paine, Y.ꢀC. Tan, and X.ꢀM. Gan, Inorg. Chem., 2001,
40, 7009.
9. A. G. Matveeva, Z. A. Starikova, E. I. Matrosov, G. V.
Bodrin, S. V. Matveev, and E. E. Nifant´ev, Zh. Neorg.
Khim., 2006, 51, 295 [Russ. J. Inorg. Chem., 2006, 51, 253
(Engl. Transl.)].
10. C. Reichardt, Solvents and Solvent Effects in Organic Chemisꢀ
try, VCH, Weincheim, 1988.
11. A. S. Borovik, V. Papaefthymiou, L. F. Taylor, O. P.
Anderson, and L. Que, J. Am. Chem. Soc., 1989, 111, 6183.
12. L. J. Bellamy, The Infrared Spectra of Complex Molecules,
Wiley, London—New York, 1957.
13. SAINTPlus. Data Reduction and Correction Program, v.6.01,
Bruker AXS, Madison (Wisconsin, USA), 1998.
14. SADABS v.2.01, Bruker/Siemens Area Detector Absorption
Correction Program, Bruker AXS, Madison (Wisconsin,
USA), 1998.
15. SHELXTL v.5.10, Structure Determination Software Suite,
Bruker AXS, Madison (Wisconsin, USA), 1998.
16. V. V. Tkachev, N. A. Bondarenko, E. I. Matrosov, E. N.
Tsvetkov, L. O. Atovmyan, and M. I. Kabachnik, Izv. Akad.
Nauk, Ser. Khim., 1981, 211 [Bull. Acad. Sci. USSR, Div.
Chem. Sci., 1981, 30 (Engl. Transl.)].
17. A. N. Chekhlov, Zh. Strukt. Khim., 1995, 36, 925 [Russ.
J. Struct. Chem., 1995, 36 (Engl. Transl.)].
18. R. Amorati, M. Lucarini, V. Mugnaini, and G. F. Pedulli,
J. Org. Chem., 2003, 68, 5198.
19. M. I. de Heer, H.ꢀG. Korth, and P. Mulder, J. Org. Chem.,
1999, 64, 6969.
20. M. I. de Heer, P. Mulder, H.ꢀG. Korth, K. U. Ingold, and
J. Lusztyk, J. Am. Chem. Soc., 2000, 122, 2355.
21. W. Levason, E. H. Newman, and M. Webster, Polyhedron,
2000, 19, 2697.
same mechanism. Although it is impossible to study the
reactions of cerium compounds by ESR,30 analysis of the
IR spectra of a mixture of oxidation products and the
structure of one of this product established by Xꢀray difꢀ
fraction provide support for this assumption.
Therefore, unlike free phenol L2 stable to oxidation,
its K salt 1 is much readily oxidized with atmospheric
oxygen. In the complexes with lanthanide nitrates,
innerꢀsphere oxidation of coordinated phenol readily
occurs already at room temperature. Taking into acꢀ
count the structure of one of oxidation products and based
on analysis of the IR spectra of a mixture of products, it
can be concluded that oxidation of phenol L2 in lanꢀ
thanide complexes and its alkyl analogs catalyzed by
copper salts occurs presumably by the same (radical)
mechanism.
In conclusion, it should be noted that phenol L2, like
its prototype, viz., bis(diphenylphosphorylmethyl)benzene
L1 (R = Ph) containing no OH groups in the central
benzene ring, is coordinated to metal salts to form
polyligand complexes with M : L = 1 : 1, 1 : 2, or 1 : 3. In
solutions, additional coordination of the oxygen atom of
the OH group was observed in all complexes of phenol L2
with rareꢀearth nitrates. In the solid phase, additional
coordination is observed only in some cases. Coordinaꢀ
tion of both phosphoryl oxygen atoms in the pendant
groups plays the major role and retains the necessary ligand
contour, which is apparently responsible for selectivity of
extraction.
We thank B. L. Tumanskii for help in performing ESR
experiments and helpful discussion.
This study was financially supported by the Council
on Grants of the President of the Russian Federation
(Federal Program for the Support of Leading Scientific
Schools, Grants NShꢀ1100ꢀ2003ꢀ3 and NShꢀ1060ꢀ
2003ꢀ3) and the Russian Academy of Sciences (State Conꢀ
tract No. 0002ꢀ251/Pꢀ09/118ꢀ125.100603ꢀ589).
References
22. M. P. Pasechnik, S. V. Matveev, D. V. Tolkachev, A. G.
Matveeva, E. I. Matrosov, Yu. M. Polikarpov, and M. I.
Kabachnik, Izv. Akad. Nauk, Ser. Khim., 1996, 1537 [Russ.
Chem. Bull., 1996, 45, 1466 (Engl. Transl.)].
23. K. Nakamoto, Infrared and Raman Spectra of Inorganic and
Coordination Compounds, 4th ed., New York—Chichester—
Brisbane—Toronto—Singapure, 1986.
1. G. V. Bodrin, M. I. Kabachnik, N. E. Kochetkova, T. Ya.
Medved´, B. F. Myasoedov, Yu. M. Polikarpov, and
M. K. Chmutova, Izv. Akad. Nauk, Ser. Khim., 1979, 2572
[Bull. Acad. Sci. USSR, Div. Chem. Sci., 1979, 28 (Engl.
Transl.)].

2534
Russ.Chem.Bull., Int.Ed., Vol. 54, No. 11, November, 2005
Matveeva et al.
24. Structure Correlation, Eds H.ꢀB. Burgi and J. D. Dunitz,
VCH, Weinheim, New York, 1994, 2.
Khim., 1982, 27, 3111 [J. Inorg. Chem. USSR, 1982, 27 (Engl.
Transl.)].
25. V. P. Solov´ev, M. S. Stukalova, E. V. Koltunova, and N. N.
Kochanova, Koord. Khim., 2003, 29, 711 [Russ. J. Coord.
Chem., 2003, 29 (Engl. Transl.)].
26. G. F. Krestov, N. P. Novoselov, I. S. Perelygin, A. M.
Kolker, L. P. Safronova, V. D. Ovchinnikova, and V. N.
Trostin, Ionnaya sol´vatatsiya (Problemy khimii rastvorov)
[Ionic Solvation (Problems of Chemistry of Solutions)], Nauka,
Moscow, 1987, 320 pp. (in Russian).
28. V. V. Ershov, G. A. Nikiforov, and A. A. Volod´kin,
Prostranstvennoꢀzatrudnennye fenoly [Sterically Hindered
Phenols], Khimiya, Moscow, 1972, pp. 352 (in Russian).
29. C. Orlando, J. Org. Chem., 1968, 33, 2516.
30. J. E. Wertz and J. R. Bolton, Electron Spin Resonance.
Elementary Theory and Practical Applications, McGrowꢀHill
Book Company, New York, 1972.
27. M. I. Kabachnik, E. I. Sinyavskaya, L. V. Tsymbal, T. Ya.
Medved´, Yu. M. Polikarpov, and G. V. Bodrin, Zh. Neorg.
Received July 6, 2005