Coordination of 2-phosphorylalkyl-substituted 1, 8-naphthyridines in complexes with lanthanide nitrates

Article abstract of DOI:10.1007/s11172-009-0189-x

The reaction of 2-phosphorylalkyl-substituted 1, 8-naphthyridines, viz., 2-[2-(diphenylphos-phoryl)propan-2-yl]-1, 8-naphthyridine (L1) and 2-[2-(diphenylphosphoryl)ethyl]-1, 8-naph-thyridine (L2), with lanthanide nitrates (Nd, Eu, or Lu) afforded complex

Full text of DOI:10.1007/s11172-009-0189-x

Russian Chemical Bulletin, International Edition, Vol. 58, No. 7, pp. 1416—1422, July, 2009
1416
Coordination of 2ꢀphosphorylalkylꢀsubstituted 1,8ꢀnaphthyridines
in complexes with lanthanide nitrates
A. G. Matveeva, P. S. Lemport, M. P. Pasechnik, R. R. Aysin, L. A. Leites, 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. Еꢀmail: phoc@ineos.ac.ru
The reaction of 2ꢀphosphorylalkylꢀsubstituted 1,8ꢀnaphthyridines, viz., 2ꢀ[2ꢀ(diphenylphosꢀ
phoryl)propanꢀ2ꢀyl]ꢀ1,8ꢀnaphthyridine (L1) and 2ꢀ[2ꢀ(diphenylphosphoryl)ethyl]ꢀ1,8ꢀnaphꢀ
thyridine (L2), with lanthanide nitrates (Nd, Eu, or Lu) afforded complexes with the metalꢀtoꢀ
ligand molar ratio of 1 : 1 and 1 : 2. Based on the IR and Raman spectroscopic data, it was found
that the coordination of the ligands L1 and L2 in all complexes occurs through the P=O group
and the nitrogen atoms of the naphthyridine moiety.
Key words: phosphorusꢀcontaining 1,8ꢀnaphthyridines, complexes, lanthanides, structure,
IR spectra, Raman spectra.
In the past decade, the synthetic and coordination
ent length with lanthanide nitrates Ln(NO3)3 (Ln = Nd,
Eu, or Lu).
chemistry of 1,8ꢀnaphthyridine and its derivatives has atꢀ
tracted great interest due to the diverse use of these comꢀ
pounds and their complexes.1,2 Among 1,8ꢀnaphthyridine
derivatives, compounds containing coordinatively active
substituents at position 2 or positions 2 and 7 are of particꢀ
ular interest. Coordination compounds of this family are
used in metalꢀcomplex catalysis,3 some of these comꢀ
pounds exhibit biological activity;1,2,4 furthermore, some
complexes have very interesting photophysical properties,5
such as luminescence.6 Although complexes with metal
cations belonging to the majority of Groups of the Periodꢀ
ic Table have been investigated,1,2,7 complexes with lanꢀ
thanides have been studied to a much lesser extent.8,9 At
the same time, it is known that lanthanide complexes with
organic polynitrogenꢀ and oxygenꢀcontaining ligands are
extensively studied and are used for the preparation of
organic light emitting diodes (OLED).10
Experimental
The solvents were purified and dried according to known proꢀ
cedures13 and saturated with argon. The salts Nd(NO3)3•6H2O,
Eu(NO3)3•5H2O (Fisher Scientific Company), and
Lu(NO3)3•xH2O (Aldrich) were used without additional purifiꢀ
cation. The water content (x = 3) in commercial lutetium nitrate
was determined experimentally.
The field of our research is the preparation of new
1,8ꢀnaphthyridine systems and the synthesis of the comꢀ
plexes of these systems with lanthanides. Taking into acꢀ
count that tertiary phosphine oxides can form a strong
coordination bond with many metals (including lanꢀ
thanides) through the lone electron pair of the phosphoryl
oxygen atom, we synthesized new phosphorusꢀcontaining
ligands, viz., monosubstituted phosphorylalkyl 1,8ꢀnaphꢀ
thyridines.11,12
The coordination properties of this type of ligands
were investigated using the example of the complexꢀ
ation of 2ꢀ[2ꢀ(diphenylphosphoryl)propanꢀ2ꢀyl]ꢀ1,8ꢀ
naphthyridine (L1) and 2ꢀ[2ꢀ(diphenylphosphoryl)ethyl]ꢀ
1,8ꢀnaphthyridine (L2) containing linkers of differꢀ
2ꢀ[2ꢀ(Diphenylphosphoryl)propanꢀ2ꢀyl]ꢀ1,8ꢀnaphthyridine
(L1) and 2ꢀ[2ꢀ(diphenylphosphoryl)ethyl]ꢀ1,8ꢀnaphthyridine (L2)
were synthesized according to procedures described previously.11,12
Synthesis of lanthanide complexes 1—12 (general procedure).
To a solution of a ligand (L1 or L2) (0.3 mmol) in chloroform
(1—2 mL), a solution of stoichiometric amount (0.3 or 0.15 mmol)
of Ln(NO3)3•nH2O in acetonitrile (2 mL) was slowly added
dropwise at room temperature, and the mixture was concentratꢀ
ed in vacuo (~5 Torr) to ~1 mL. The precipitate that formed was
filtered off, washed with diethyl ether, and dried in vacuo
(~1 Torr) at 100 °C. The decomposition temperatures, the eleꢀ
mental analysis data, the appearance, and the yields of the comꢀ
plexes are given in Table 1.
IR spectra of the compounds prepared as KBr pellets and as
Nujol or hexachlorobutadiene mulls were recorded in the region
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1375—1381, July, 2009.
1066ꢀ5285/09/5807ꢀ1416 © 2009 Springer Science+Business Media, Inc.

Ln complexes with (POꢀalkyl)ꢀ1,8ꢀnaphthyridines
Russ.Chem.Bull., Int.Ed., Vol. 58, No. 7, July, 2009
1417
400—4000 cm–1 on a Nicolet Magna IRꢀ750 FTꢀIR specꢀ
trometer.
tridentate naphthyridines L1 and L2 favor the simultaꢀ
neous coordination of the P(O) group and one or two
nitrogen atoms to one metal ion.
In complexes with metal ions, 1,8ꢀnaphthyridine and
its derivatives exhibit different coordination modes. Acꢀ
cording to the Cambridge Structural Database,* unsubstiꢀ
tuted 1,8ꢀnaphthyridine in mononuclear complexes can
act as both the monodentate7,16,17 (I) and bidentate ligand
and can be bound to metal ions either symmetrically7,18,19
(II) or nonsymmetrically7,20 (III).
Raman spectra of the solid samples in the region 200—4000 cm–1
and of a solution of complex 12 in nitromethane (c = 0.186 mol L–1
)
were obtained using a LabRAM laser Raman spectrometer
equipped with a cooled CCD detector. The excitation line was
that at 632.8 nm of a He—Ne laser with an output power not
exceeding 10 mW.
The computer curve fitting analysis of the spectral lines with
a complicated profile was carried out with the use of the Oriꢀ
gin 7.5 program.
Quantum chemical calculations of the geometry and the norꢀ
mal coordinate analysis were carried out with the use of the
Gaussian03 program package14 by the DFT method with the
PBE functional and the 6ꢀ31G(d,p) basis set.15
Results and Discussion
The reactions of naphthyridines L1 and L2 with lanthanꢀ
ide nitrates Ln(NO3)3 (Ln = Nd, Eu, or Lu) taken in the
molar ratios M : L = 1 : 1 and 1 : 2 afford complexes 1—12,
which were isolated in the solid state (Table 1).
In biꢀ and polynuclear complexes with 1,8ꢀnaphthyriꢀ
dine,17,21 the ligand is coordinated in a bridging mode
(IV) through both nitrogen atoms (the symmetric or nonꢀ
In studies of the coordination properties of naphthyꢀ
ridines L1 and L2 with respect to lanthanide cations, the
question about the ligands denticity, in particular, about
the involvement of the nitrogen atoms in the coordination
is the most interesting. The structures of both potentially
* More than 50 crystal structures of 1,8ꢀnaphthyridine compꢀ
lexes are available in the Cambridge Structural Database (CSD);
in the present study, we give references to only some of these
structures.
Table 1. Yields, decomposition temperatures, elemental analysis data, and the color of powderꢀlike complexes 1—12
Comꢀ
pound
Composition
Yield
(%) comp./°С
T.deꢀ
Found
Calculated
Molecular formula
Color of
the powder
(%)
N
C
H
P
1
Nd(L1)(NO3)3•4H2O
Eu(L1)(NO3)3
83
90
81
75
85
80
74
82
85
79
86
87
>205
>290
>210
>223
>220
>219
>180
>120
>150
>165
>141
>145
35.71 3.72
35.66 3.77
38.79 2.97
38.89 2.98
37.68 2.88
37.67 2.89
51.50 3.87
51.39 3.94
49.68 3.93
50.18 4.09
49.49 3.69
49.96 3.83
38.02 2.81
9.25 3.97
9.04 4.00
9.64 4.41
9.86 4.36
9.58 4.21
9.55 4.22
9.20 5.80
9.12 5.76
9.02 5.53
8.97 5.63
8.93 5.42
8.87 5.60
9.80 4.32
C23H21N5NdO10P•4H2O
Paleꢀlilac
Cream
White
2
C23H21EuN5O10
P
P
3
Lu(L1)(NO3)3
C23H21LuN5O10
4
Nd(L1)2(NO3)3•4H2O
Eu(L1)2(NO3)3•H2O
Lu(L1)2(NO3)3
C46H42N7NdO11P2•4H2O
C46H42EuN7O11P2•H2O
C46H42LuN7O11P2
White
5
White
lustrous
White
6
7
Nd(L2)(NO3)3
C22H19N5NdO10
C22H19EuN5O10P•4H2O
C22H19LuN5O10
P
Paleꢀlilac
Cream
White
38.38 2.78 10.17 4.50
8
Eu(L2)(NO3)3•4H2O
Lu(L2)(NO3)3
34.31 3.45
34.39 3.54
36.75 2.67
36.73 2.66
50.35 3.59
50.47 3.66
49.89 3.55
50.11 3.63
48.87 3.41
49.04 3.55
8.98 3.95
9.11 4.03
9.59 4.30
9.74 4.31
9.23 5.88
9.39 5.92
9.14 5.79
9.30 5.88
8.99 5.72
9.10 5.75
9
P
10
11
12
Nd(L2)2(NO3)3•4H2O
Eu(L2)2(NO3)3
C44H38N7NdO11P2•4H2O
C44H38EuN7O11P2
White
White
Lu(L2)2(NO3)3
C44H38LuN7O11P2
Yellowish

1418
Russ.Chem.Bull., Int.Ed., Vol. 58, No. 7, July, 2009
Matveeva et al.
symmetric coordination depending on the nature of the
complexꢀforming agent).
In the presence of active electronꢀdonating substituꢀ
ents in positions 2 and 7 of the naphthyridine core, the
new coordination possibilities could arise.
The coordination modes of the ligands and the strucꢀ
tures of complexes 1—12 were studied by vibrational specꢀ
troscopy. The IR and Raman spectra of both the free
ligands and their complexes were recorded.
~1370 cm–1, whereas the bidentate nitrato groups appear
in the IR spectra26 as ν(NO) at ~1500 cm–1, νs(NO2) at
1030 cm–1, and νas(NO2) at ~1300 cm–1. It is the latter
bands that are observed in the IR spectra of complexes
1—12, whereas these bands could not be identified in the
Raman spectra because of their low intensities.
The frequencies of the salient analytical bands of the
complexes under study compared to those of the free
ligands are given in Tables 2 and 3.
The complete vibrational spectrum of 1,8ꢀnaphthyriꢀ
dine was first published in 1973 along with the assignment
of normal modes to symmetry species but not to particular
forms.22 The refinement of this assignment based on norꢀ
mal mode calculations was reported in the study.23 For
the correct band assignment, we have carried out quanꢀ
tum chemical calculations24 of the geometry, as well as of
normal mode frequencies and eigenvectors, for the free
1,8ꢀnaphthyridine molecule and its model 1 : 1 complex
with FeCl3. The complex with the Fe ion was chosen as the
model to simplify the computation. The most intense
lines in the Raman spectra of the 1,8ꢀnaphthyridine
and 2ꢀmethylꢀ1,8ꢀnaphthyridine molecules are the lines
of totally symmetric modes with frequencies at ~1360,
The IR spectra of some complexes (1, 4, 5, 8, and 10)
exhibit bands at 3200—3650 cm–1 characteristic of outerꢀ
sphere water molecules.
Complexes [Ln(L1)(NO3)3]•nH2O (1—3). In the IR
spectra of complexes 1—3, the P=O absorption bands are
shifted to low frequencies of ~1130 cm–1, and the bands
of nitrato groups suggest their bidentate coordination.
The bands of free nitrato (~1370 cm–1) and phosphoryl
(~1177 cm–1) groups are absent. The frequencies of the
naphthyridine core in the IR and Raman spectra (see Table 2)
are shifted to high frequencies by approximately 20 cm–1
and suggest the coordination of the nitrogen atoms. Howꢀ
ever, as mentioned above, these data do not allow the
determination of the coordination mode of the ligands.
Attempts to prepare crystals of complexes 1—3 suitable
for Xꢀray diffraction failed. The Xꢀray powder diffraction
pattern of complex 1 shows the amorphous state of the
sample. Therefore, we compared the vibrational specꢀ
tra of complexes 1—3 with those of the crystalline
complexes of another stoichiometric composition, viz.,
[Nd(L1)3]3+•3(NO3)–•MeCN (13), [Eu(L1)3]3+•3(NO3)–•
~770, and ~530 cm–1 24
According to the results of the
.
normal coordinate analysis (NCA), all these modes beꢀ
long to the naphthyridine moiety and are heavily mixed
(group vibrations). The most intense line at ~1360 cm–1
corresponds to a totally symmetric mode of complex oriꢀ
gin with the participation of νC=C and δC—H coordinates,
and the lines at ~770 and ~530 cm–1 correspond to
"breathing" vibrations of the aromatic moiety with
the participation of both nitrogen atoms. In the IR specꢀ
trum, the naphthyridine core is characterized by a band
of medium intensity at ~1550 cm–1, which also belongs
to a mixed mode with the participation of the nitroꢀ
gen atoms.
[Eu(NO3)3•4H2O]•MeCN (14), and [Lu(L1)3]3+
•
3(NO3)–•[Lu(NO3)3•3H2O]•2 MeCN•0.5H2O (15),
Table 2. Frequencies of coordinationꢀsensitive bands in the viꢀ
brational spectra (ν/cm–1) of the ligand L1, complexes 1—6, and
crystalline complexes 13—15
The calculation for the model complex [Fe(napy)Cl3]
(napy is 1,8ꢀnaphthyridine) optimized the geometry with
two unequal Fe—N bonds and showed that the complex
formation should shift the aboveꢀmentioned naphthyriꢀ
dine modes to higher frequencies by 15—20 cm–1. Highꢀ
frequency shifts of some IR bands of 1,8ꢀnaphthyridine in
the case of its bidentate coordination with lanthanides
have been reported previously.8 The same shifts are obꢀ
served in the spectra of all the complexes studied in the
present work. However, it should be emphasized that due
to complex mode eigenvectors, these shifts do not allow
one to distinguish between particular coordination modes
of the nitrogen atoms, i.e., to chose between the structures
I—III. The coordination of the phosphoryl oxygen atom
to metal ions, including lanthanide ions, leads to a shift of
the ν(P=O) band by 30—35 cm–1 to lower frequencies.25
The spectral manifestations of the free and coordiꢀ
nated nitrato groups were also investigated in detail.26
The free nitrato groups are observed in the IR spectra at
Comꢀ ν(P=O)
pound (IR)
Vibrations of the
naphthyridine core
ν(N=O) ν (NO2)
as
(IR)
(IR)
IR
Raman
L1
1
2
3
4
1177
1129
1133
1136
1127
1544
1563
1564
1567
1562
1368
777
795
797
801
795,
781*
797,
777
800,
777
797
798
802
—
—
1382
1383
1390
1383,
1371*
1383,
1370
1388,
1370
1383
1383
1390
1490
1480
1498
1470
1303
1308
1300
1300
5
6
1131
1133
1564
1566
1480
1497
1314
1315
13 24
14 24
15 24
1128
1130
1133
1563
1564
1566
—
—
1482
1498
1300
1314
* The frequency was obtained by the computer curve fitting analꢀ
ysis of the spectral lines with a complicated profile.

Ln complexes with (POꢀalkyl)ꢀ1,8ꢀnaphthyridines
Russ.Chem.Bull., Int.Ed., Vol. 58, No. 7, July, 2009
1419
Table 3. Frequencies of coordinationꢀsensitive bands in the viꢀ
brational spectra (ν/cm–1) of the ligand L2 and complexes 7—12
whose structures have been established by Xꢀray diffraction
previously.24 In spite of the different compositions, comꢀ
pounds 13—15 contain the complex cation [Ln(L1)3]3+ as
the main structural fragment. For all the lanthanides
(Ln = Nd, Eu, and Lu) under study, these cations are
isostructural, the three ligands L1 being coordinated to
the central lanthanide atom in the O,N,Nꢀtridentate fashꢀ
ion. Thus, the coordination polyhedron is formed by
nine atoms.
Comꢀ ν(P=O)
Vibrations of the
ν(N=O) ν (NO2)
as
pound (IR)
naphthyridine core
(IR)
(IR)
IR
Raman
L2
7
8
9
10
1183
1144
1144
1146
1144
1549
1567
1568
1571
1566
1374
781
791
792
796
791,
777*
792,
777
795,
775
–
–
1382
1383
1387
1383,
1371*
1382,
1369
1387,
1368
1480
1500
1500
1470
1299
1304
1301
1304
11
12
1148
1565,
1554
1557,
1480
1500
1309
1306
1158,
(1143)* 1570 sh
* The frequency was obtained by the computer curve fitting analꢀ
ysis of the spectral lines with a complicated profile.
plexes under consideration is also coordinated in a tridenꢀ
tate fashion.
Complexes 1—3 are soluble in polar solvents. The
aboveꢀmentioned data suggest that the interaction of the
ligand L1 with lanthanide nitrates affords the neutral monoꢀ
dentate complexes [Ln(η3ꢀO,N,NꢀL1)(η2ꢀO,OꢀNO3)3]•
•nH2O (Ln = Nd, Eu, or Lu, n = 0 or 4), in which the liꢀ
gand is coordinated in a tridentate fashion, and the coordiꢀ
nation sphere is completed by three bidentate nitrato groups.
The vibrational spectra of crystalline complexes 13—15
in the region of analytical frequencies of the ligand are
identical to the spectra of the corresponding monoligand
complexes 1—3 (see Table 2 and Fig. 1). Therefore, it may
be concluded with certainty that the ligand L1 in the comꢀ
I (arb. units)
1383
798
1370
543
543
777
5
14
543
540
2
777
1368
L1
750
1000
1250
Δν/cm–1
Fig. 1. Raman spectra of the free ligand L1 and its complexes with europium nitrate with a metalꢀtoꢀligand ratio of 1 : 1 (2) and 1 : 2 (5)
and of crystalline complex 14.

1420
Russ.Chem.Bull., Int.Ed., Vol. 58, No. 7, July, 2009
Matveeva et al.
ligand is coordinated both through the phosphoryl oxygen
atom and the nitrogen atoms of the naphthyridine core.
Attempts to prepare crystalline complexes with the
ligand L2 failed. However, the spectra of complexes 7—9
are similar to the spectra of the corresponding complexes
1—3, although the shifts of the analytical bands of the
ligand in the spectra of complexes 7—9 (see Table 3) are
somewhat smaller than those in the spectra of related comꢀ
plexes 1—3 containing the ligand with the short linker
(see Table 2). Complexes 7—9 are moderately soluble in
polar solvents. The aboveꢀconsidered data suggest that both
groups of the monoligand complexes are structurally simꢀ
ilar, i.e., the ligand L2 in complexes 7—9 is also coorꢀ
dinated in a tridentate fashion, whereas the three nitꢀ
rato groups are bidentate: [Ln(η3ꢀO,N,NꢀL2)(η2ꢀO,Oꢀ
NO3)3]•nH2O (Ln = Nd, Eu, or Lu, n = 0 or 4). The
coordination number of the lanthanide cation is nine.
Complexes [Ln(L2)2(NO3)3]•nH2O (10—12). The freꢀ
quencies of the vibrations of bisꢀligand complexes 10—12
are similar to the corresponding frequencies of monoliꢀ
gand complexes 7—9 (see Table 3). In addition, the vibraꢀ
tional spectra of complexes 10—12, like the spectra of bisꢀ
ligand complexes 4—6 containing the ligand L1 with the
short linker, also exhibit the splitting of the Raman lines
corresponding to the vibrations of the naphthyridine moiꢀ
ety (see Table 3, Fig. 2 (the lutetium complexes)).
As opposed to the complexes containing the ligand
with the short linker, the splitting is observed not only in
the Raman spectra but also in the IR spectra (the band at
~1570 cm–1). As exemplified by the Raman spectrum of
readily soluble bisꢀligand complex 12 (see Fig. 2), this
splitting is not the Davydov splitting because it is retained
in the spectrum of a solution. Hence, it can be suggested
that complexes 10—12 are structurally similar to comꢀ
plexes 4—6, [Ln(η3ꢀO,N,NꢀL2)(η2ꢀO,OꢀNO3)3]•nH2O
(Ln = Nd, Eu, or Lu; n = 0 or 4). Both ligand molecules
are coordinated in a tridentate fashion but not strictly
equivalent, and three nitrato groups are coordinated in a
bidentate fashion. The coordination number of lanthanide
is 12, and the coordination polyhedron has the composiꢀ
tion [LnN4O8]. Of all the complexes under study, comꢀ
pounds 10—12 are most readily soluble in polar solvents
(acetonitrile, nitromethane, acetone, and ethanol).
X = CMe2 (L1), CH2CH2 (L2)
The coordination sphere of the lanthanide cation in
complexes 1—3 is formed by nine atoms, viz., two nitroꢀ
gen atoms of the naphthyridine moiety, one phosphoryl
oxygen atom of the ligand, and six oxygen atoms of three
bidentate nitrato groups, and the complexes have the
following composition [LnN2O7].
Complexes [Ln(L1)2(NO3)3]•nH2O (4—6). The vibraꢀ
tional frequencies of complexes 4—6 are similar to those
of the complexes with composition 1 : 1 (see Table 2). Howꢀ
ever, unlike the Raman spectra of monoligand complexes
1—3, the spectra of bisꢀligand complexes 4—6 show the
doublet splitting of the lines corresponding to the vibraꢀ
tions of the aromatic naphthyridine system (see Fig. 1).
Apparently, the splitting is caused by a certain nonequiꢀ
valence of the coordinated ligand molecules due to the
steric hindrance in the crowded coordination polyhedron
[LnN4O8], which is formed by 12 atoms in the bisꢀligand
complexes. It should be noted that such a high coordinaꢀ
tion number is not unusual for lanthanide complexes.27
For example, the Xꢀray diffraction data19 showed that the praꢀ
seodymium atom in the complex with 1,8ꢀnaphthyridine
has the coordination number 12; the same coordination
number is suggested for the complexes of 1,8ꢀnaphthyriꢀ
dine with lanthanide nitrates and perchlorates.8 Thereꢀ
fore, it can be concluded that bisꢀligand complexes 4—6
are also neutral, and both ligands are coordinated in a triꢀ
dentate fashion, whereas the three nitro groups are coorꢀ
dinated in a bidentate fashion: [Ln(η3ꢀO,N,NꢀL1)2(η2ꢀ
O,OꢀNO3)3]•nH2O (Ln = Nd, Eu, or Lu, n = 0, 1, or 4).
It should be noted that the changes in the vibrational
spectra of the complexes containing the ligand L1 with the
short linker are much more substantial than those observed
in the spectra of the complexes containing the ligand L2
with the longer linker. For example, the shift of the P=O
frequency for monoligand complexes 1—3 is 48—41 cm–1
,
whereas the shift for complexes 7—9 is only 39—37 cm–1
(see Tables 2 and 3). The shifts of the IR bands and
the Raman lines corresponding to the vibrations of the
naphthyridine cores of complexes 1—3 are 19—23, 14—22,
and 18—24 cm–1 for the bands at 1560, 1380, and
790 cm–1, respectively, whereas these shifts for complexes
X = CMe2 (L1), CH2CH2 (L2)
Complexes [Ln(L2)(NO3)3]•nH2O (7—9). The posiꢀ
tions of the IR bands and the Raman lines in the vibrational
spectra of complexes 7–9 (see Table 3) indicate that the

Ln complexes with (POꢀalkyl)ꢀ1,8ꢀnaphthyridines
Russ.Chem.Bull., Int.Ed., Vol. 58, No. 7, July, 2009
1421
I (arb. units)
793
776
545
538
1368
12s
1387
775
536
545
796
12
1387
796
545
9
782
1374
535
L2
600
800
1000
1200
1400 Δν/cm–1
Fig. 2. Raman spectra of the free ligand L2 and its complexes with lutetium nitrate with a metalꢀtoꢀligand ratio of 1 : 1 (9) and 1 : 2 (12)
and of a solution of complex 12 in nitromethane (12s). The crossed lines refer to the solvent.
7—9 are 18—22, 8—13, and 10—15 cm–1, respectively
3. (a) R. Zong, R. P. Thummel, J. Am. Chem. Soc., 2005, 127,
12802; (b) C. Bianchini, H. M. Lee, P. Barbaro, A. Meli,
(see Tables 2 and 3). This suggests that the tridentate ligand
S. Moneti, F. Vizza, New J. Chem., 1999, 23, 929; (c) S. A.
L1 with the short linker forms more stable complexes with
Moya, R. Pastene, R. Sariego, R. Sartori, P. Aguirre, H. Le
lanthanide nitrates compared to the analogous ligand L2
with the longer linker. Most likely, this is due to the fact
that the coordination of L1 leads to the formation of the
Bozec, Polyhedron, 1996, 15, 1823; (d) A. E. M. Boelrijk,
T. X. Neenan, J. Reedijk, J. Chem. Soc., Dalton Trans., 1997,
4561; (e) T. Tomon, D. Ooyama, T. Wada, K. Shiren,
K. Tanaka, J. Chem. Soc., Chem. Commun., 2001, 1100.
more stable sixꢀmembered metallacycle.
The shifts and splitting of the IR bands and the Raman
lines corresponding to the vibrations of the naphthyridine
system increase in the series Nd—Eu—Lu in all the groups
of the compounds studied. At the same time, the shift of
the band of the coordinated P=O groups decreases in the
same series. This seems to be associated with a change in
the strength of coordination bonds. Presumably, the
strength of the bonds with the nitrogen atoms of the naphꢀ
thyridine core increases, whereas the bond with the phosꢀ
phoryl oxygen atom becomes weaker with a decrease in
the ionic radius of the metal atom.
Thus, 2ꢀphosphorylalkylꢀsubstituted 1,8ꢀnaphthyꢀ
ridines L1 and L2 in the mononuclear complexes with lanꢀ
thanide nitrates (neodymium, europium, and lutetium)
exhibit the highest possible O,N,Nꢀdenticity regardless of
the linker length, the composition of the complex, and the
size of the lanthanide cation.
4. R. Leon, C. de los Rios, J. MarcoꢀContelles, O. Huertas,
X. Barril, F. J. Luque, M. G. Lopez, A. G. Garcia, M. Villarꢀ
roya, Biorg. Med. Chem., 2008, 16, 7759.
5. (a) S. M. Scott, A. K. Burrell, P. A. Cocks, K. C. Gordon,
J. Chem. Soc., Dalton Trans., 1998, 3679; (b) S. A. Moya,
R. Schmidt, R. Pastene, R. Sartori, U. Müller, G. Frenzen,
Organometallics, 1996, 15, 3463; (c) A. von Zelewsky, G. Greꢀ
maud, Helv. Chim. Acta, 1988, 71, 1108; (d) S. M. Scott, K. C.
Gordon, A. K. Burrell, J. Chem. Soc., Dalton Trans., 1998, 2873.
6. (a) Y. Chen, X.ꢀJ. Zhao, X. Gan, W.ꢀF. Fu, Inorg. Chim.
Acta, 2008, 361, 2335; (b) J.ꢀF. Zhang, W.ꢀF. Fu, X. Gan,
J.ꢀH. Chen, Dalton Trans., 2008, 3093; (c) K. Morita, Y. Sato,
T. Seino, S. Nishizawa, N. Teramae, Org. Biomol. Chem.,
2008, 6, 266; (d) Y. Zhou, Y. Xiao, X. Qian, Tetrahedron
Lett., 2008, 4, 3380; (e) Y.ꢀY. Sun, J.ꢀH. Liao, J.ꢀM. Fang,
P.ꢀT. Chou, C.ꢀH. Shen, C.ꢀW. Hsu, L.ꢀC. Chen, Org. Lett.,
2006, 8, 3713; (f) C.ꢀM. Che, C.ꢀW. Wan, K.ꢀY. Ho, Z.ꢀY.
Zhou, New J. Chem., 2001, 25, 63; (i) R.ꢀH. Uang, C.ꢀK.
Chan, S.ꢀM. Peng, C.ꢀM. Che, J. Chem. Soc., Chem. Comꢀ
mun., 1994, 2561.
References
7. W. W. Paudler, R. M. Sheets, Adv. Heterocyclic Chem., 1983,
33, 147.
1. V. P. Litvinov, Adv. Heterocycl. Chem., 2006, 91, 189.
2. V. P. Litvinov, Usp. Khim., 2004, 73, 692 [Russ. Chem. Rev.
(Engl. Transl.), 2004, 73, 637].
8. (a) R. J. Foster, D. G. Hendricker, Inorg. Chim. Acta, 1972,
6, 371; (b) R. J. Foster, R. L. Bodner, D. G. Hendricker,
J. Inorg. Nucl. Chem., 1972, 34, 3795.

1422
Russ.Chem.Bull., Int.Ed., Vol. 58, No. 7, July, 2009
Matveeva et al.
9. D. G. Hendricker, R. J. Foster, J. Inorg. Nucl. Chem., 1972,
34, 1949.
10. M. A. Katkova, A. G. Vitukhnovskii, M. N. Bochkarev, Usp.
Khim., 2005, 74, 1193 [Russ. Chem. Rev. (Engl. Transl.), 2005,
74, 1089].
11. G. V. Bodrin, P. S. Lemport, S. V. Matveev, P. V. Petrovskii,
E. E. Nifant´ev, Mendeleev Commun., 2007, 17, 25.
12. P. S. Lemport, G. V. Bodrin, M. P. Pasechnik, A. G. Matveꢀ
eva, P. V. Petrovskii, A. V. Vologzhanina, E. E. Nifant´ev,
Izv. Akad. Nauk, Ser. Khim., 2007, 1846 [Russ. Chem. Bull.,
Int. Ed., 2007, 56, 1911].
357, 3666; (d) E. L. Enwall, K. Emerson, Acta Cryst., 1979,
35B, 2562; (e) G. W. Bushnell, K. R. Dixon, M. A. Khan,
Can. J. Chem., 1978, 56, 450; (f) M. Munakata, ShengꢀGang
Yan, M. Maekawa, M. Akiyama, S. Kitagawa, J. Chem. Soc.,
Dalton Trans., 1997, 4257; (g) M.ꢀJ. Bermejo, J.ꢀI. Ruiz,
X. Solans, J. Vinaixa, Inorg. Chem., 1988, 27, 4385.
17. W. P. Griffith, T. Yu. Koh, A. J. P. White, D. J. Williams,
Polyhedron, 1995, 14, 2019.
18. (a) B. G. Harvey, A. M. Arif, R. D. Ernst, Polyhedron, 2004,
23, 2725; (b) J. M. Epstein, J. C. Dewan, D. L. Kepert, A. H.
White, J. Chem. Soc., Dalton Trans., 1974, 1949; (c) P. Singh,
A. Clearfield, I. Bernal, J. Coord. Chem. 1971, 1, 29; (d) H. Naꢀ
kajima, H. Nagao, K. Tanaka, J. Chem. Soc., Dalton Trans.,
1996, 1405.
13. C. Reichardt, Solvents and Solvent Effects in Organic Chemisꢀ
try, VCH, Weincheim, 1988.
14. M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria,
M. A. Robb, J. R. Cheeseman, J. A. Montgomery, Jr.,
T. Vreven, K. N. Kudin, J. C. Burant, J. M. Millam, S. S.
Iyengar, J. Tomasi, V. Barone, B. Mennucci, M. Cossi,
G. Scalmani, N. Rega, G. A. Petersson, H. Nakatsuji,
M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa,
M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai,
M. Klene, X. Li, J. E. Knox, H. P. Hratchian, J. B. Cross,
V. Bakken, C. Adamo, J. Jaramillo, R. Gomperts, R. E.
Stratmann, O. Yazyev, A. J. Austin, R. Cammi, C. Pomelli,
J. W. Ochterski, P. Y. Ayala, K. Morokuma, G. A. Voth,
P. Salvador, J. J. Dannenberg, V. G. Zakrzewski, S. Dapꢀ
prich, A. D. Daniels, M. C. Strain, O. Farkas, D. K. Malick,
A. D. Rabuck, K. Raghavachari, J. B. Foresman, J. V. Ortiz,
Q. Cui, A. G. Baboul, S. Clifford, J. Cioslowski, B. B. Steꢀ
fanov, G. Liu, A. Liashenko, P. Piskorz, I. Komaromi, R. L.
Martin, D. J. Fox, T. Keith, M. A. AlꢀLaham, C. Y. Peng,
A. Nanayakkara, M. Challacombe, P. M. W. Gill, B. Johnꢀ
son, W. Chen, M. W. Wong, C. Gonzalez, J. A. Pople,
GAUSSIAN 03, Revision C.01, Gaussian Inc., Wallingford
CT, 2004.
19. A. Clearfield, R. Gopal, R. W. Olsen, Inorg. Chem., 1977,
16, 911.
20. J. C. Dewan, D. L. Kepert, A. H. White, J. Chem. Soc.,
Dalton Trans., 1975, 490.
21. (a) M. Munakata, M. Maekawa, S. Kitagawa, M. Adachi,
H. Masuda, Inorg. Chim. Acta, 1990, 167, 181; (b) D. Gatteꢀ
schi, C. Mealli, L. Sacconi, J. Am. Chem. Soc., 1973, 95,
2736; (c) A. Bencini, E. Berti, A. Caneschi, D. Gatteschi,
E. Giannasi, I. Invernizzi,Chem. Eur. J., 2002, 8, 3660;
(d) C. Mealli, F. Zanobini, Chem.Commun, 1982, 97.
22. J. T. Carrano, S. C. Wait, Jr., J. Mol. Spectrosc., 1973, 46, 401.
23. P. J. Chappell, I. G. Ross, J. Mol. Spectrosc., 1977, 66, 192.
24. A. G. Matveeva, P. S. Lemport, L. A. Leites, R. R. Aysin,
A. V. Vologzhanina, Z. A. Starikova, M. P. Passechnik, E. E
Nifant´ev, Inorg. Chim. Acta, 2009, 362, 3187.
25. (a) W. Levason, E. H. Newman, M. Webster, Polyhedron,
2000, 19, 2697; (b) A. G. Matveeva, A. S. Peregudov, E. I.
Matrosov, Z. A. Starikova, G. I. Timofeeva, S. V. Matveev,
G. V. Bodrin, E. E. Nifant´ev, Dokl. Akad. Nauk, 2007, 413,
771 [Dokl. Chem. (Engl. Transl.), 2007, 413, 95].
15. (a) J. P. Perdew, K. Burke, M. Ernzerhof, Phys. Rev. Lett.,
1996, 77, 3865; (b) W. J. Hehre, R. Ditchfield, J. A. Pople,
J. Chem. Phys., 1972, 56, 2257; (c) M. M. Francl, W. J.
Petro, W. J. Hehre, J. S. Binkley, M. S. Gordon, D. J. Deꢀ
Frees, J. A. Pople, J. Chem. Phys., 1982, 77, 3654; (d) V. Rasꢀ
solov, J. A. Pople, M. Ratner, T. L. Windus, J. Chem. Phys.,
1998, 109, 223.
26. K. Nakamoto, Infrared and Raman spectra of Inorganic and
Coordination Compounds, 4th ed., New York—Chichester—Brisꢀ
bane—Toronto—Singapure, 1986.
27. V. P. Solov´ev, M. S. Stukalova, E. V. Koltunova, N. N.
Kochanova, Koord. Khim., 2003, 29, 711 [J. Coord. Chem.
(Engl. Transl.), 2003, 29].
16. (a) T. Suzuki, Inorg. Chim. Acta, 2006, 359, 2431; (b) F. Zaꢀ
mora, M. Sabat, B. Lippert, Inorg. Chim. Acta, 1998, 282,
237; (c) T. Koizumi, K. Tanaka, Inorg. Chim. Acta, 2004,
Received November 19, 2008;
in revised form March 3, 2009