Oxonitrates VO(NO3)3 and MoO2 (NO 3)2 and nitronium and nitrosonium nitratometallates as nitrating agents

Article abstract of DOI:10.1134/S0036023609120109

Dissolution of vanadium in anhydrous HNO₃ followed by exposure of the solution in a dessicator over P₂O₅ gave liquid vanadyl trinitrate (I). The X-ray diffraction analysis of I was carried out for a single crystal grown on

Full text of DOI:10.1134/S0036023609120109

ISSN 0036-0236, Russian Journal of Inorganic Chemistry, 2009, Vol. 54, No. 12, pp. 1902–1908. © Pleiades Publishing, Inc., 2009.
Original Russian Text © I.V. Morozov, E.V. Karpova, D.M. Palamarchuk, A.Yu. Gavrilova, S.I. Troyanov, 2009, published in Zhurnal Neorganicheskoi Khimii, 2009, Vol. 54,
No. 12, pp. 1985–1991.
COORDINATION COMPOUNDS
Oxonitrates VO(NO3)3 and MoO2(NO3)2 and Nitronium
and Nitrosonium Nitratometallates as Nitrating Agents
I. V. Morozov, E. V. Karpova, D. M. Palamarchuk, A. Yu. Gavrilova, and S. I. Troyanov
Department of Chemistry, Moscow State University, Moscow, 117234 Russia
e-mail: morozov@inorg.chem.msu.ru
Received April 14, 2009
Abstract—Dissolution of vanadium in anhydrous HNO3 followed by exposure of the solution in a dessicator
over P2O5 gave liquid vanadyl trinitrate (I). The X-ray diffraction analysis of I was carried out for a single crys-
tal grown on cooling the liquid in a sealed capillary. The structure is composed of VO(NO)3 molecules in which
the V atom has an unusually high C.N. 7; it coordinates the terminal O atom and three bidentate nitrate groups
to form a distorted pentagonal bipyramid as the coordination polyhedron with the terminal O atom occupying
one axial vertex. Using the GAMESS program package, ab initio calculation of the structure of VO(NO3)3 in
the liquid phase was carried out. It was shown that in all three physical states, vanadyl trinitrate retains its
molecular structure almost invariable. Toluene and naphthalene nitration using I and (NO2)[Fe(NO3)4],
NO[Cu(NO3)3], (NO)3/4(NO2)1/4[Zr(NO3)5], and MoO2(NO3)2 proceeds at high rates at low temperatures to
give an unusually high para-nitrotoluene percentage in the products as compared with the ortho-isomer. The
activity of the studied compounds in the nitration of naphthalene decreases in the series VO(NO3)3 >
(NO)3/4(NO2)1/4[Zr(NO3)5] > MoO2(NO3)2.
DOI: 10.1134/S0036023609120109
Nitration is an important reaction of organic chem-
istry both for laboratory practice and for industry. The
nitro derivatives formed, which are mainly aromatic,
are important final products or intermediates in the pro-
duction of a broad spectrum of products, in particular,
explosives, construction materials, and pharmaceuti-
cals.
The use of inorganic nitrates as nitrating agents has
been largely constrained until now by the complexity of
preparation of these compounds. The synthesis of
anhydrous nitrates or oxonitrates requires most often
the use of nitrogen oxides N2O4 or N2O5 in the presence
of organic solvents and under conditions eliminating
the access of air moisture [3]. For example, vanadyl
trinitrate VO(NO3)3 is formed in the reaction of dinitro-
gen pentoxide with VOCl3 or V2O5 [2, 4]. To date, the
structure of this compound has been known only in the
gas phase [5]. We developed a new synthetic approach
that markedly simplified the synthesis of anhydrous
nitrates and oxonitrates including both known and new
ones [6, 7].
Although nitration is a thoroughly studied industrial
process, modern requirements to the efficiency, selec-
tivity, and environmental safety of production pro-
cesses call for nitration methods that comply with the
“green chemistry” concept [1]. This refers first of all to
the use of sulfuric acid-free nitration methods. There-
fore, the search for alternative approaches to nitration is
in progress. One of these approaches is the use of inor-
ganic nitrates as nitrating agents. According to avail-
able publications, the use of nitrates may increase the
selectivity of nitration and decrease the undesirable
resinification and oxidation secondary processes.
In this study we used new synthetic approaches to
prepare a number of nitrates and oxonitrates:
VO(NO3)3,
MoO2(NO3)2,
NO[Cu(NO3)3],
(NO2)[Fe(NO3)4], and (NO)3/4(NO2)1/4[Zr(NO3)5]. The
structure of VO(NO3)3 in the crystalline and liquid
phases was established for the first time. The obtained
compounds were tested as nitrating agents in nitration
of toluene and naphthalene.
For example, it was shown [2] that vanadyl trinitrate
VO(NO3)3 is a strong and convenient nitrating agent for
a series of benzene derivatives. A high yield of nitration
products and minor contribution of side reactions were
also noted for substrates containing electron-donating
substituents, namely, anisole and N-methylaniline. It
was suggested [2] that the reagent is simultaneously an
active catalyst capable of being regenerated in the pres-
ence of nitrogen oxides.
EXPERIMENTAL
The following chemicals were used: analytical
grade Cu(NO3)2 · 3H2O, Fe(NO3)3 · 9H2O, P2O5, and V;
reagent grade ZrO(NO3)2 · 2H2O, H2MoO4, toluene,
naphthalene, and CH2Cl2.
1902

OXONITRATES VO(NO3)3 AND MoO2(NO3)2 AND NITRONIUM
Table 1. IR spectrum of VO(NO3)3
1903
ν, cm–1*
Assignment [11]
ν(NO) of bidentate NO3
Experiment
Calculation
[11]
1630 s
1610 s
1202 s
1646 s
1621 s
1223 s
1635 s
1615 s
1216 m
1209 m
1196 m
νas(NO2) of bidentate NO3
1016 s
1002 m
1014 s
1007 m
ν(V=O)
996 s
965 s
796 m
774 s
686 w
990 s
968 s
773 m
768 s
659 w
995 s
962 s
775 s
νs(NO2) of bidentate NO3
δs(VO2N) of the ring, δs of bidentate NO3
690 w
682 w
δ(ONO) of bidentate NO3
νas(VO2) of bidentate NO3
450 s
445 s
452 s
* Designations for line intensity: s is strong, m is medium, w is weak.
Synthesis of Nitrates and Oxonitrates
The phase composition of the crystalline samples
was determined by powder X-ray diffraction. The
hygroscopic crystals were ground in a dry box, placed
on a quartz holder, and tightly coated by a polystyrene
film wetted with mineral oil. The measurement was car-
ried put on a DRON 3M instrument using a CoKα radi-
ation in the 2θ range of 5°–60°. The single-phase nature
of the obtained samples was confirmed by similarity of
the experimental X-ray diffraction patterns and theoret-
ical ones calculated from single crystal X-ray diffrac-
tion data.
The yellow VO(NO3)3 sample was identified by
comparing its IR spectrum with published data. For
recording the IR spectrum, a drop of liquid VO(NO3)3
in a dry box was placed into a polyethylene bag and
tightly sealed. The spectrum was recorded in the range
of 4000–400 cm–1 on a PE-1600 FTIR spectrometer.
The spectrum of VO(NO3)3 and band assignment are
summarized in Table 1.
Anhydrous nitric acid was synthesized by a reported
procedure [8]. For preparing nitrosonium salts and
anhydrous d-metal oxonitrates NO[Cu(NO3)3],
(NO2)[Fe(NO3)4], (NO)3/4(NO2)1/4[Zr(NO3)5], and
MoO2(NO3)2, saturated solutions of the nitrate hydrates
Cu(NO3)2 · 3H2O, Fe(NO3)3 · 9H2O, and ZrO(NO3)2 ·
2H2O and α-molybdic acid in anhydrous nitric acid
were prepared. For VO(NO3)3 preparation, vanadium
metal was dissolved in anhydrous nitric acid. The
resulting nitric acid solutions were placed in an evacu-
ated dessicator over P2O5. Under these conditions,
nitric acid vapor reacts with P2O5 to give N2O5, which
readily passes to the gas phase and partially decom-
poses to N2O4 (NO2) and O2. Nitrogen oxides are taken
by the starting nitric acid solution and irreversibly bind
water. Over a period of 7–15 days, the liquid phase is
gradually removed to give crystalline products. This
synthetic method is described in detail in the literature
[6, 7, 9].
The bands corresponding to C–C and C–H vibra-
tions of the polyethylene film are not superimposed on
the vanadyl nitrate molecule vibrations and are not
given in Table 1. The obtained IR spectrum fully corre-
sponds to published data [10].
No crystalline products were formed in the synthe-
sis of VO(NO3)3 but after 10 days, the solution sepa-
rated into two phases, the heavier phase colored light
yellow and the lighter phase colored light brown. Dur-
ing the subsequent 5 days, the ligher liquid completely
evaporated. The further analysis showed that the
remaining viscous yellow liquid was VO(NO3)3 with
HNO3 and nitrogen oxide impurities. These were
removed by the following procedure: high cooling in
liquid nitrogen vapor resulted in separation, from the
yellow thick liquid, of several drops of a lighter brown-
ish liquid not miscible with the yellow liquid. These
drops were removed by a pipette in a dry box.
Structure Determination for VO(NO3)3
in the Crystalline and Liquid Phases
To carry out single crystal X-ray diffraction, a liquid
VO(NO3)3 sample was placed in a thin-walled glass
capillary, which was then sealed. The X-ray diffraction
experiment was carried out on a IPDS (STOE) instru-
ment (MoKα radiation, λ = 0.71073 Å, graphite mono-
chromator). By multiple repeating of cooling (freez-
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 54 No. 12 2009

1904
MOROZOV et al.
Table 2. Crystal data, X-ray diffraction experiment param-
they were processed to isolate the most intense compo-
nent; as a result, the group of reflections caused by dif-
fraction from one crystal was distinguished and reflec-
tions from other (three or four) components were dis-
carded. The crystal data, X-ray diffraction experiment
parameters, and structure refinement details for
VO(NO3)3 are summarized in Table 2, and selected
bond lengths and bond angles are in Table 3. The full
set of crystal data is deposited with the Inorganic Crys-
tal Structure Database (FIZ, Karlsruhe and NIST,
Gaithersburg) with the registration number ICSD
420596. Note that the accuracy of determination of the
geometric structure of VO(NO3)3 is not very high, due
to the inevitable presence of accidental components
from other crystals in the X-ray diffraction pattern. The
error in V–O bond length determination was 0.012–
0.015 Å, and the size of OVO angles was determined to
an accuracy of 0.7°–0.8°. Nevertheless, the absolute
values for the bond lengths and angles are in quite sat-
isfactory agreement with the results of gas-electron dif-
fraction study of VO(NO3)3 [11] (Table 3).
eters, and structure refinement details for VO(NO3)3
System
Space group
a, Å
Monoclinic
P21/c
10.079(3)
13.203(4)
5.686(2)
102.47(2)
738.8(4)
4
b, Å
c, Å
β, deg
V, Å3
Z
dcalcd, g/cm3
μ, mm–1
Crystal size, mm
T, K
2.274
1.399
0.5 × 0.3 × 0.3
200(2)
θ
max, deg
23.8
The number of reflections, measured/inde- 3475/1132
pendent
The number of reflections with F2 > 2σ(F2)
495
The structure of VO(NO3)3 in the liquid phase was
determined by an ab initio quantum chemical calcula-
tion of the equilibrium geometry of this molecule. As
the starting geometry, the geometry of gaseous vanadyl
nitrate determined previously [11] from gas-electron
diffraction data was used. The calculation was carried
out using the PC GAMESS program package [12] by
restricted Hartree–Fock method in the self-consistent
field approximation, SCF/RHF. A polarized basis set
comprising heavy effective potentials for the inner
shells was used for the V atom and correlation-consis-
tent polarized valence double-zeta basis sets were used
for all other atoms. First, the structure of the VO(NO3)3
molecule in the gas phase was calculated. The reliabil-
ity of this calculation was confirmed by good agree-
ment between the geometry found for an isolated
VO(NO3)3 molecule with gas-electron diffraction data
(Table 3). For determining the vanadyl nitrate structure
in the liquid phase, a continual model was used [13];
the dielectric constant was taken to be 80 and the solva-
tion shell radius was assumed to be 4 Å.
The number of reflections/least square re-
finement parameters
1121/127
R1
0.140
0.284
wR2
Table 3. Interatomic distances (Å) and bond angles in the
VO(NO3)3 molecule in the gas, liquid, and crystalline phases
Physical state of VO(NO3)3
Bond
gas
liquid
calculation
crystal
[11]
V–O(10)
V–O(1)
V–O(2)
V–O(4)
V–O(5)
V–O(7)
V–O(8)
Angle
1.607(7)
2.154(9)
1.971(5)
2.154(9)
1.971(5)
1.483
2.041
1.984
2.041
1.984
1.482
2.037
1.980
2.037
1.980
2.284
1.931
1.573(15)
2.084(13)
2.014(12)
2.085(13)
1.989(15)
2.229(15)
1.975(13)
Using the equilibrium geometry of the vanadyl
nitrate thus obtained, the vibrational spectrum of this
molecule was calculated. It has thirty-six principal
vibrations of which twenty vibrations are in the IR
range. All of the found vibration frequencies are real,
which indicates that the stationary state is true. In Table
1, the frequencies of the strongest vibrations present in
the experimental IR spectrum of liquid vanadyl trini-
trate are compared with theoretical vibration frequen-
cies multiplied by the scaling factor of 0.9. The assign-
ment of vibration frequencies of the experimental IR
spectrum corresponds to that predicted by quantum
chemical calculation. The satisfactory agreement
between the theoretical and experimental IR spectra
indicates that the found configuration coincides with
2.258(20) 2.253
1.915(7) 1.919
O(10)VO(8) 94.5(13) 100.7
O(10)VO(2) 96.3(9) 102.5
100.7
102.7
100.7(8)
100.6(7)
ing)–heating (partial melting) cycles for a sample in a
capillary under a stream of the X-ray diffraction unit
cooling gas, VO(NO3)3 was crystallized as crystal clots
rather than as a powder formed upon the primary cool-
ing. After X-ray diffraction data had been collected, the real one.
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 54 No. 12 2009

OXONITRATES VO(NO3)3 AND MoO2(NO3)2 AND NITRONIUM
Table 4. Reactant ratio and composition of the products of toluene nitration
1905
Product composition, mol %
Run
no.
Nitrating agent
(NA)
T, °C
ν(T) : ν(NA)
ENA*
o-/p-**
T
o-MNT p-MNT 2,4-DNT 2,6-DNT
1
2
3
4
5
6
0
VO(NO3)3
4 : 1
2 : 1
4 : 1
3 : 1
4 : 1
4 : 1
50
54
52
30
53
25
27
21
23
33
20
21
23
25
25
37
23
23
0
0
2.0
0.92
1.9
2.1
2.0
4.2
1.2
MoO2(NO3)2
(NO2)[Fe(NO3)4]
NO[Cu(NO3)3]
MoO2(NO3)2
(NO2)[Fe(NO3)4]
0
0
0.84
0.92
0.89
0.87
0.91
0
0
0
0
50
3.4
0.6
6
25
ν(NO2–)
ν(NA)
----------------------
is the efficiency of nitrating agent.
Notes: * E
=
NA
ν(o-MNT)
--------------------------
ν(n-MNT)
** o-/p- –
.
Toluene and Naphthalene Nitration
quantified using the triplet at 7.82 ppm, and for mono-
nitronaphthalene, a doublet at 8.56 ppm was used.
For nitration, suspensions of inorganic nitrate (10 wt %)
in dichloromethane pre-distilled over P2O5 were pre-
pared. For this purpose, dichloromethane was added to
a weighed portion of the nitrate and the mixture was
magnetically stirred in a tightly closed vessel for
10 min. In the case of vanadyl nitrate, a true solution
formed, which is consistent with published data [2].
The resulting suspension of a nitrating agent (NA) was
added dropwise to a stirred 10% dichloromethane solu-
tion of toluene (T) or naphthalene (N) kept at a constant
temperature. The temperature of the reaction medium
was maintained constant using a water bath or a cooling
ice–salt mixture. The reaction was carried out for
30 min, then excess water was added, and the organic
fraction was separated, washed with water to pH 7, and
dried over anhydrous Na2SO4. The solvent was
removed on a rotary evaporator and the organic prod-
ucts were analyzed in the reaction mixture by 1H NMR
The weights of reactant samples were 0.1 to 1 g in
most of experiments, which corresponds to 1 to
50 mmol. Since the nitrating agents used are hygro-
scopic, all operations with these compounds (weighing,
preparation of the starting suspensions or solutions)
were carried out in a dry box under nitrogen, while the
proper nitration reactions were carried out under condi-
tions excluding a contact with air moisture. Toluene
was nitrated at 0 and 50°ë, and naphthalene was
nitrated at –5°C. The starting reactant ratio and the
composition of the nitration products are presented in
Table 4 for toluene (runs 1–6) and in Table 5 for naph-
thalene (runs 7–12).
RESULTS AND DISCUSSION
It follows from Table 3 that going from the crystal-
line phase to liquid or gas phase is not accompanied by
pronounced changes in the geometry of the VO(NO3)3.
The somewhat underestimated V–O distance for the
vanadyl group in the liquid and gas phases can be attrib-
uted to the lack of electron correlation corrections in the
1
spectroscopy. The H NMR spectra were recorded on
an Avance Bruker spectrometer operating at 400 Hz at
28°ë in CDCl3. The proton signals were assigned rely-
ing on published data [14].
The composition of the toluene nitration products self-consistent field method.
was determined from the integral intensity ratio of the
In the VO(NO3)3 molecule, the vanadium atom has
signals for aromatic protons in the 1H NMR spectra of
reaction mixtures. The 2,4-dinitrotoluene (DNT) con-
tent was determined using the HC(3) proton signal
manifested as a doublet with the spin–spin coupling
constant J = 2.0 Hz at about 8.80 ppm; 2,6-DNT was
determined based on the doublet at 7.98 ppm, J =
8.1 Hz; para-mononitrotoluene (MNT) was deter-
mined using the doublet at 8.08 ppm, J = 8.6 Hz; and
ortho-MNT was determined using the doublet at
7.93 ppm, J = 8.1 Hz.
an unusually high C.N. = 7 (Fig. 1). The vanadium
coordination polyhedron is a distorted pentagonal
bipyramid where one axial vertex is occupied by the
terminal O(10) atom, which forms the shortest V–O
distance (1.573(15) Å) and the other axial vertex is
occupied by the O atom of the asymmetric bidentate
nitrate group, this bond being the longest (V–O(7),
2.229(15) Å) (the indicated distances correspond to
crystalline VO(NO3)3 (Table 3)). The equatorial plane is
formed by the second O atom of this nitrate group and
four more O atoms of two symmetrical bidentate NO3
The relative content of 1,8-dinitronaphthalene
(1,8-DNN) in the naphthalene nitration products was groups located atV–O distances of 1.975(13)–2(085) Å
found based on the triplet at 7.75 ppm; 1,5-DNN was (cf. 2.03 Å). The distortion of the pentagonal bipyramid
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 54 No. 12 2009

1906
MOROZOV et al.
Table 5. Results of naphthalene nitration
Product composition, mol %
ν(NO2–)
----------------------
ν(NA)
ν(N)
Run
no.
----------------
Nitrating agent (NA)
VO(NO3)3
ENA
=
ν(NA)
N
MNN
1,5-DNN
1,8-DNN
7
8
4 : 1
3 : 1
4 : 1
1 : 3
1 : 3
1 : 3
42
50
77
0
58
50
23
0
0
0
0
0
2.3
(NO)3/4(NO2)1/4[Zr(NO3)5]
MoO2(NO3)2
2.0
9
0
0
0.92
0.67
0.43
0.38
10
11
12
VO(NO3)3
21
7
79
22.5
10
(NO)3/4(NO2)1/4[Zr(NO3)5]
MoO2(NO3)2
0
70.5
85
0
5
is due to the fact that the OVO bond angles involving nitration, which occurs by a homogeneous mechanism.
This is consistent with published data [2] and is con-
firmed by toluene and naphthalene nitration experi-
ments.
the same nitrate group range from 61° to 64°, which is
somewhat smaller than the perfect value (for example,
the angle involving axial oxygen atoms, O(10)VO(7), is
162.5(7)°). In addition, the vanadium atom is shifted
from the equatorial plane toward the terminal O(10)
atom: the O(10)VO(equat. plane) angles range from
94.1(7)° to 103.4(7)°. In the crystal structure of vanadyl
trinitrate, each VO(NO3)3 molecule is surrounded by
twelve other molecules and forms O···O contacts at
least 2.9–3.15 Å long; the molecules are more closely
packed in the (a0c) plane (four neighboringV atoms are
located at 4.8 to 5.7 Å distances, while along the b axis
two nearest V···V contacts are 6.8 Å) (Fig. 2).
Toluene nitration experiments were carried out with
deficiency of nitrating agents; as a result, no DNT was
formed at 0°ë (Table 4, runs 1–4); however, at 50°ë,
DNT was detected in the reaction products (Table 4,
runs 5 and 6).
Attention is attracted by unusually high content of
p-MNT in the toluene nitration products (Table 4, last
column). Indeed, when MoO2(NO3)2, NO[Cu(NO3)3], or
(NO2)[Fe(NO3)4] was used (Table 4, runs 2–6), the
Ó-MNT to p-MNT ratio in the reaction products was
0.84–0.92, whereas with conventional nitrating agents,
Due to its molecular structure, VO(NO3)3 is soluble
in organic solvents. This is favorable for high rates of ν(o-MNT)/ν(p-MNT) was 1.2 to 1.6 [15, 16].
O(10)
O(5)
O(6)
O(2)
O(1)
N(2)
V
O(3)
N(1)
O(4)
O(8)
O(7)
N(3)
O(9)
Fig. 1. Structure of the VO(NO ) molecule in the crystal structure of vanadyl trinitrate.
3 3
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 54 No. 12 2009

OXONITRATES VO(NO3)3 AND MoO2(NO3)2 AND NITRONIUM
1907
a
V
O
N
b
Fig. 2. Crystal structure of VO(NO ) projected along the c axis.
3 3
For stoichiometric description of the nitration, the As temperature increases (run 5, equation (5)), ENA
parameter ENA (the efficiency of a nitrating agent) char-
increases considerably compared to that in run 2 and
acterizing the average number of nitro groups intro- reaches the maximum possible value corresponding to
duced in the substrate per molecule of the nitrating the formation of molybdic acid:
agent was calculated. In the case of toluene (runs 1–6),
2í + MoO2(NO3)2
2NT + H2MÓO4.
(5)
the ENA value was found from the data of Table 4 using
the relation
This means that nitration occurs stepwise via a num-
ber of inorganic intermediates. In the case of VO(NO3)3
and nitration of toluene, ENA = 2 corresponds to the for-
mation of polymeric VO2(NO3) (reaction (1)), possibly
in the hydrated form, while in the case of naphthalene
nitration, this value increases, indicating involvement
of the last nitrate group in the nitration. According to
published data [2], nitration of toluene at room temper-
ature with a 10% solution of VO(NO3)3 in dichlo-
romethane at the molar ratio T : VO(NO3)3 = 1 : 1
affords a mixture of MNT and DNT, whereas the ratio
T : VO(NO3)3 = 3 : 2 gives only MNT. This may also
attest to the successive formation of several inorganic
intermediates, probably, with decreasing nitrating
capacity, during the process.
ENA = ν(NO2-)/ν(NA) = 0.01[χ(MNT)
+ 2χ(DNT)] · [ν0(T)/ν(NA)],
where ν0(T) and ν(NA) are the initial amounts of
toluene and the nitrating agent, ν(NO2-) is the total
number of nitro groups introduced in toluene, χ(MNT)
and χ(DNT) are the MNT and DNT contents in the
nitration products (mol %). In the naphthalene nitration
experiments, the ENA value was calculated in a similar
way from the data of Table 5.
The parameter ÖNA allows one to take into account
the stoichiometric ratio between the amount of con-
verted substrate and the nitrating agent and to compose
the scheme of nitration:
Naphthalene nitration experiments with excess
nitrating agent revealed the sequence of relative activi-
ties of nitrating agents in which the compounds can be
arranged: VO(NO3)3 > (NO)3/4(NO2)1/4[Zr(NO3)5] >
MoO2(NO3)2. The highest activity is observed for
vanadyl nitrate, which is soluble in organic solvents due
to its molecular structure; hence, nitration occurs as a
single-phase reaction in this case.
2T + VO(NO3)3
í + MoO2(NO3)2
2NT + VO2(NO3) + H2O, (1)
NT + MÓO2(OH)(NO3), (2)
2NT + Fe(NO3)3 · H2O, (3)
2í + (NO2)[Fe(NO3)4]
2í + NO[Cu(NO3)3] + 0.5 O2
2NT + Cu(NO3)2 · H2O.(4)
The above equations correspond to runs 1–4. The
molecular formulas of inorganic products are tentative;
however, in some cases, they may be close to the true
formulas. For example, in the case of MoO2(NO3)2, on
It is noteworthy that the use of acetonitrile as the sol-
vent considerably decreases the nitrating activity of
going to nitration of an excess of naphthalene, the ENA VO(NO3)3, which is in line with reported data [2]. Even
value remains invariable; this may be indicative of in the presence of a threefold molar excess of VO(NO3)3
existence of rather stable hydroxymolybdenyl nitrate
with the molecular formula close to MÓO2(OH)(NO3).
with respect to the substrate, most of naphthalene
remain unchanged in acetonitrile.
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 54 No. 12 2009

1908
MOROZOV et al.
5. B. A. Smart, H. E. Robertson, D. W. H. Rankin, et al.,
Our experiments on toluene and naphthalene nitra-
J. Chem. Soc., Dalton Trans., 473 (1999).
tion by a 10% solution of VO(NO3)3 in dichlo-
romethane confirmed the reported data about this com-
pound as a potent and convenient nitrating agent. In
addition, a series of nitronium and nitrosonium
nitratometallates, (NO2)[Fe(NO3)4], NO[Cu(NO3)3], and
(NO)3/4(NO2)1/4[Zr(NO3)5], and also molybdenyl nitrate
MoO2(NO3)2, were tested as nitrating agents. It was
shown that nitration of naphthalene and toluene occurs
rapidly, the resulting mixture of mononitrotoluenes
being enriched in the para-isomer. The nitro com-
pounds formed can be readily separated from the inor-
ganic side products by washing with water and contain
almost no oxidation products or other impurities.
6. K. O. Znamenkov, I. V. Morozov, and S. I. Troyanov,
Zh. Neorg. Khim. 49 (2), 172 (2004) [Russ. J. Inorg.
Chem. 49 (2), 172 (2004)].
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S. I. Troyanov, Izv. Akad. Nauk, Ser. Khim., No. 1, 92
(2005).
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by G. Brauer (Ferdinand Enke, Stuttgart, 1981; Mir,
Moscow, 1985), Vol. 1.
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ACKNOWLEDGMENTS
This work was supported by the Russian Foundation
for Basic Research, project no. 07-03-01142.
12. Alex A. Granovsky, PC GAMESS version 7.0 (Dragon)
(MSU, Moscow, 2006).
13. M. W. Wong, M. J. Frisch, and K. B. Wiberg, J. Am.
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