1
812
EMEL’YANOV, FEDOTOV
The present work deals with the study of the ruthe-
nium state in nitric acid solutions treated with sodium solutions, including ruthenium- and zinc-containing
nitrite (so-called nitration).
solutions, was carried out by the following procedure:
-mL portions of 2–3 M HNO were placed in 25-mL
The interaction of sodium nitrite with 2–3 M HNO3
5
3
volumetric flasks, 0–0.2 mL of solution I was added,
EXPERIMENTAL
and a zinc nitrate sample (0–6.25 mmol) was dis-
The complex Na [RuNO(NO ) OH] · 2H Owas solved. To the resulting solution, a required volume of
2
2 4
2
synthesized from pure grade (Russian State Standard) 8.33 M NaNO solution was added portionwise at room
2
ruthenium trichloride by a routine procedure [12]. The temperature, and the resulting solution was heated for
X-ray powder diffraction pattern of the synthesized 30–40 min at 80°ë. The residual acidity of the solution
compound coincided with the pattern calculated from was determined by titration of a 0.1-mL sample
X-ray crystallography data [13], and the IR spectrum diluted 100-fold with a standard alkali solution in the
was consistent with the spectrum described in [14]. The presence of Methyl Orange. The final solutions con-
–
2
other reactants were no worse than chemically pure.
tained (0 –1.2) ×10 mol/L of ruthenium and 0–1.25
mol/L of zinc nitrate.
An initial solution for nitration was prepared by dis-
solving 3 mmol of Na [RuNO(NO ) OH] · 2H O in a
2
2 4
2
1
: 1 HNO (conc) + H O mixture. The solution was
3 2
RESULTS AND DISCUSSION
The 14N NMR spectrum of solution I shows the
heated in a water bath for 16 h and then evaporated to a
minimum volume (wet salts). Then, 10 mL of water was
added, and the solution was evaporated once more. The strong signal due the free nitrate ion (δ = –1.5 ppm), the
residue was dissolved in 5 mL of 3 M HNO on heating signal due to the coordinated nitrate ion (δ =
3
−
10.5 ppm), initially described in [4], and the broad
signal due to the coordinated nitroso group (δ ~
and kept in a water bath for 1 h. After that, the solution
was transferred to a 10-mL volumetric flask, and the
–
2
volume was completed to the mark with 3 M HNO . The
3
−18 ppm) [5–9]. No signal of coordinated NO is
resulting 0.3 M ruthenium solution in ~3 å HNO3
99
observed. The Ru NMR spectrum of this solution is
(solution I) was used in experiments.
almost featureless. This can be caused by the presence
Nitrated nitric acid solutions of ruthenium for NMR of several complex species in this solution, the concen-
were prepared as follows. To solution I (3 mL), water tration of each of them being below the detection limit
1
7
enriched in é(0.2 mL) was added, and nitration was of the spectrometer, as well as by polymerization of
1
5
carried out by adding solid Na NO at room tempera- complex particles, which strongly broadens spectral
2
lines. Thus, ruthenium in this solution can be in the
form of several nitroso nitrato aqua complexes, which
are, most likely, not only monomeric.
ture and heating the resulting solutions for 30 min at
8
0°ë in a sealed system. Solution II was obtained by
1
5
the interaction of solution I with 0.216 g of Na NO ;
2
1
4
solution III, by the interaction of II with 1.118 g of
Na NO ; solution IV, by the interaction of III with Na
Figure 1 shows the N NMR spectrum of a 0.33 M
[RuNO(NO OH] · 2H O solution in 3 M HNO
1
5
)
2
2
2
4
2
3
1
5
kept for one day at room temperature. In addition to the
line of the free nitrate ion (δ = –1.3 ppm), the spectrum
shows the lines of coordinated nitrite ions (δ ~ 70 ppm,
0
.418 g of Na NO ; solution V, by keeping solution IV
2
for 25 days at room temperature; and solutionVI, by the
interaction of solution V kept for nine months with
0
spectra were recorded. A total of five series of spectra
were recorded for solutions with concentrations of
H 2.7 (solution II), 1.5 (III), 0.06 (IV), 0.2 (V), and
1
5
the range of the H O–Ru–NO trans coordinates),
2 2
.034 g of Na NO . After cooling the solutions, NMR
2
nitrate ions (δ = –9.8 ppm), and nitroso group (δ ~ –18
ppm, the H O–Ru–NO coordinate) with an intensity
2
+
ratio close to 2 : 1 : 1 if the weakening of the lines of
coord
0
0
.12 mol/L (VI). To estimate the acidity of solutions, coordinated nitrite ions (NO2
) is taken into account
.1 mL was sampled and diluted 100-fold, and the pH
[
5]. This means that, in 3 M HNO , two of the four
3
was measured on an Anion 4100 ionometer.
coordinated nitro groups of the initial complex
99
14
15
17
2–
The Ru, N, N, and ONMR spectra of aqueous [RuNO(NO ) OH] are destroyed within one day,
2
4
solutions were recorded on a Bruker MSL-400 spec- which is consistent with the conclusions [15–19] that
trometer operating at the frequencies 18.42, 28.9,
0.56, and 54.2 MHz, respectively. Chemical shifts
δ scale, ppm) were measured with respect to the signals
coord
NO2
in this complex exhibits a strong trans influ-
4
ence and that cis-dinitronitrosoruthenium compounds are
(
99
stable. The Ru NMR spectrum of this solution (T = 323 K)
is represented by one strong line (δ = 3993 ppm, the width
W1/2 ~ 1600 Hz), which retains its characteristics in the
1
4
15
of external references: 1 M NaNO ( N) or K NO
3
3
1
5
17
(
N), water ( O), and 0.5 M ä [Ru(CN) ]solution
4 6
9
9
(
Ru). The error of determination of δ depended on the
spectrum recorded 40 days later (δ = 3987 ppm, W1/2
~
1
5
line width and was no more than 0.1 ppm for N, no
1600 Hz). Taking into account the presence of the sig-
14
17
more than 2 ppm for N and O, and no more than nal due to the coordinated nitrate ion, we may assume
99
20 ppm for Ru.
that the predominant ruthenium form is the complex
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 51 No. 11 2006