Coordination germanium(IV) compounds with nitrosubstituted benzoylhydrazones of salicylaldehyde

Article abstract of DOI:10.1023/A:1013755502556

New germanium(IV) complexes with N-[X-benzoyl]hydrazones of salicylaldehyde (X-H₂L, where X = 2-, 3-, and 4-NO₂; H₂L = C₆H₄-CO-NH-NCH-C₆H ₄OH) with the compositions [Ge(2-NO

Full text of DOI:10.1023/A:1013755502556

Russian Journal of Coordination Chemistry, Vol. 28, No. 1, 2002, pp. 15–18. Translated from Koordinatsionnaya Khimiya, Vol. 28, No. 1, 2002, pp. 17–20.
Original Russian Text Copyright © 2002 by Seifullina, Shmatkova, Mazepa.
Coordination Germanium(IV) Compounds with Nitrosubstituted
Benzoylhydrazones of Salicylaldehyde
I. I. Seifullina, N. V. Shmatkova, and A. V. Mazepa
Mechnikov University, ul. Petra Velikogo 2, Odessa, 270100 Ukraine
Bogatskii Physicochemical Institute, National Academy of Sciences of Ukraine,
Chernomorskaya doroga 86, Odessa, 270080 Ukraine
Received December 13, 2000
Abstract—New germanium(IV) complexes with N-[X-benzoyl]hydrazones of salicylaldehyde (X-H2L, where
X = 2-, 3-, and 4-NO2; H2L = C6H4–CO–NH–NCH–C6H4OH) with the compositions [Ge(2-NO2–L)2], [Ge(3-
NO2–L)2], and [Ge(4-NO2–L)2] were synthesized. The data of IR, UV, and 1H, 13C NMR spectroscopy showed
that the complexes had an octahedral structure and ligand coordination through the nitrogen atom of the azome-
thine group and two oxygen atoms of the doubly deprotonated form of the ligand. The thermal stability of the
complexes was studied. The specific features of the mass spectrometric behavior of the substances in the gas
phase under electron impact were considered.
INTRODUCTION
corresponding nitrobenzoic chlorides [4], and salicyl-
aldehyde (high-purity grade) were used. Organic sol-
vents (methanol, diethyl ether, DMF, and acetone) were
dehydrated in accordance with known procedures [5].
Hydrazones were prepared through condensation of
salicylaldehyde with the above-mentioned hydrazides
in methanol using the general procedure from [6] in 60–
80% yields. Salicylalhydrazones were identified using
elemental analysis data, the presence of a peak in the
mass spectra with m/z = 285 [M]+, and the melting
points of 190, 200, and 260°C for 2-, 3-, and 4-NO2–
H2L, respectively.
In order to establish the regularities that govern the
correlation between the physicochemical properties
and structure, researchers usually study coordination
compounds of a complex-forming agent with certain
organic molecules which have different substituents or
arrangements of these substituents. This is of particular
urgence in biologically active substances because it is
important to extend this series of compounds and estab-
lish the correlation between the properties and biologi-
cal activity.
In this work, we chose germanium tetrachloride
(GeCl4) and three benzoylhydrazones of salicylalde-
hyde (H2L = C6H4–CO–NH–NCH–C6H4OH) with the
nitro group in different (2-, 3-, 4-) positions of the ben-
zene ring (X-H2L, where X = 2-, 3-, 4-NO2) as the
objects of study for the following reason. Researchers’
interest in the diverse biological activity exhibited by
both germanium-containing compounds [1] and ben-
zoylhydrazones and their complexes with various met-
als [2, 3] has increased in recent years.
For C14H11N3O4
anal. calcd. (%):
C 58.95
H 3.86
N 14.74
Found (%):
2-NO2–H2L
3-NO2–H2L
4-NO2–H2L
C 58.80
C 58.87
C 59.10
H 3.84
H 3.89
H 3.87
N 14.68
N 14.81
N 14.79
The complexes [Ge(2-NO2–L)2] (I), [Ge(3-NO2–
L)2] (II), and [Ge(4-NO2–L)2] (III) were synthesized
according to the following procedure. GeCl4 (0.0025 mol)
was added with continuous stirring to a hot saturated
solution of 2-NO2–H2L (3-NO2–H2L)(0.005 mol) or a
suspension of 4-NO2–H2L (0.005 mol) in methanol
(200 ml). The resulting solutions of I and II were boiled
with a reflux condenser for 1 and 0.5 h, respectively,
until crystallization began followed by distillation of
methanol to V = 30 ml. Then, II was left to stand for a
day for further crystallization. The mixture obtained
from the synthesis of III was stirred at T = 50–60°C
The task of the present study was to develop proce-
dures for the synthesis of new coordination compounds
of germanium(IV), to perform a comprehensive study
of them using mass spectrometry and UV, IR, and 1H,
13C spectroscopy, and to establish the influence of the
nitro group position on the ligand coordination and
some physicochemical properties of the complexes
formed.
EXPERIMENTAL
GeCl4 (special purity grade), hydrazides of 2-, 3-, until the white color of the precipitate changed to yel-
and 4-nitrosubstituted benzoic acid prepared according low (0.5 h). All products of the synthesis were sepa-
to the general procedure through hydrazinolysis of the rated on a Schott filter. Compounds I and II were
1070-3284/02/2801-0015$27.00 © 2002 åÄIä “Nauka /Interperiodica”

16
SEIFULLINA et al.
Data from the mass spectrometric study of complexes I–III
II III
Mass spectra were obtained on an MX-1320 instru-
ment by directly injecting a sample into the ionization
region at an ionizing voltage of 70 eV.
I
m/z
I, %
m/z
I, %
m/z
I, %
Diffraction patterns of the compounds were
obtained on a DRON-3 diffractometer with CoKα radi-
ation and an Fe filter.
NMR spectra of solutions of the complexes in
DMSO-d6 were recorded on a VXR-300 spectrometer
(Varian) with frequencies of 300 and 75.4 MHz for 1H
and 13C, respectively. Chemical shifts of signals were
recalculated relative to TMS.
76
77
17.1
26.4
22.0
17.4
11.4
20.6
20.6
37.2
60.8
18.6
72.1
50.2
100.0
27.4
32.3
76
77
17.9
19.8
30.0
58.5
10.0
13.5
17.2
21.2
52.8
22.3
73.7
51.8
100.0
33.8
23.4
76
77
28.6
18.0
69.7
96.1
10.2
19.3
31.7
36.6
50.8
22.0
81.7
55.8
100.0
33.6
25.9
104
150
179
191
193
195
636
637
638
639
640
641
642
104
150
179
191
193
195
636
637
638
639
640
641
642
104
150
179
191
193
195
636
637
638
639
640
641
642
RESULTS AND DISCUSSION
The molar ratio Ge : L = 1 : 2 corresponds to the
found empirical formula of complexes I–III. Taking
into account the data on electroconductivity (λ, Ohm–1
cm2 mol–1: I, 8.3; II, 12.9; and III, 9.5) and mass spec-
trometry (m/z 640[Ge(X–L)2]), these compounds are
nonelectrolytes with the composition [Ge(X–L)2].
X-ray powder diffraction analysis confirmed that
compounds I–III were individual and pure. Their X-ray
diffraction diagrams are characterized by an intrinsic
set of interplanar distances, which excludes admixtures
of the initial ligands.
washed with ether, III was washed with hot acetone,
and all products were dried above CaCl2. The yields
were 85, 80, and 70%, for I, II, and III, respectively.
Complexes I–III are crystalline yellow substances
soluble in DMF and nitrobenzene and insoluble in other
organic solvents.
Elemental analysis of the products obtained was
performed on a semiautomatic CHN-analyzer. Chlorine
was determined mercurometrically [7], and germanium
was determined through potentiometric titration of
tripyrocatechol-germanic acid on an Ionomer EV-74
instrument [8].
Comparing the thermogravimetric patterns of
hydrazones and the complexes, we found that the ther-
molysis of the latter was not accompanied by ligand
elimination. This was indicated by the absence of
ligand melting effects in the thermogravimetric patterns
of complexes I–III. Complexes I–III are characterized
by a high thermal stability: at first, melting takes place
at 300, 310, and 420°C, respectively, and then the exo-
thermic process of thermodecomposition occurs to
form GeO2.
Detailed analysis of the mass spectra of I–III (table)
showed the presence of a group of peaks of molecular
ions, whose mass corresponded to the complex species
GeL2 mainly containing the most abundant germanium
isotope 74Ge. The main course of fragmentation under
electron impact results in the formation of fission ger-
manium-containing ions, which is characteristic of sta-
ble complexes of the chelate type:
For C26H18N6O8Ge C 52.62 H 2.82 N 13.15 Ge 11.37
anal. calcd. (%):
Found (%):
I
C 52.60 H 2.81 N 13.17 Ge 11.10
C 52.00 H 2.82 N 13.14 Ge 11.30
C 52.40 H 2.82 N 13.13 Ge 11.34
II
III
IR absorption spectra (400–4000 cm–1) were
recorded on a Specord 75 IR spectrophotometer accord-
ing to the procedure of molding samples with KBr.
UV spectra of solutions of the complexes in DMF
were recorded on a Specord UV-VIS spectrophotome-
ter.
M+
[GeO2C7H6]+, m/z 195.
The intensity of this process is determined by the
ligand structure and increases with an increase in the
distance between the nitro group and germanium ion.
The intensity of the peak of ions m/z 195 for com-
pounds I–III is equal to 19.4, 21.2, and 36.6%, respec-
The molar electroconductivity of 10–3 M solutions
of the complexes in DMF was measured using a
C.L.R.E. 7-8 conductometer.
Thermogravimetric studies were performed on a tively. This correlates with an increase in the thermal
Q derivatograph (Paulik-Paulik-Erdey system). The stability of complexes I–III and values of the energy of
samples were heated in air from 20 to 1000°C at a rate formation calculated for them using the HyperChem
of 10 K/min.
5.02 program according to the AM-1 molecular
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 28 No. 1 2002

COORDINATION GERMANIUM(IV) COMPOUNDS
17
mechanics method (E, kcal/mol): –6979.2 (I), –7156.8 pared to the formation of the five-membered cycle in
(II), and –7257.2 (III).
complex I.
The comparison of the UV spectra of solutions of
the ligands and complexes in DMF shows that the
bands in the spectra of the ligands (ν, cm–1 (lnε):
2-NO2, 30569 (9.45); 3-NO2, 30000 (9.66); and 4-NO2,
29330 (9.76)) corresponding to the transitions of the
CONCLUSIONS
Thus, our studies suggest that, in complexes I–III,
the ligands manifest themselves as tridentate, their
coordination gives five- and six-membered conjugated
metallocycles, and a coordination number of 6 is real-
ized, which is characteristic of Ge(IV) [14].
π
π* azomethine bond [9] in the spectra of com-
plexes I and III undergo a hypsochromic shift; in the
spectrum of II, the shift is bathochromic (ν, cm–1 (lnε):
I, 31000 (10.47); II, 29800 (10.69); III, 29625 (10.57).
This indicates that the electron density redistribution in
molecules of I–III is caused by N-coordination at the
azomethine group.
R
CH
N
N
O
O
O
O
Ge
This is reflected in the IR spectra of I–III as the low-
frequency shift of the ν(C=N) band by 10–15 cm–1
compared to the spectra of the ligands and as the
appearance of a new band in the region of 610–620 cm–1
N
N
CH
R = 2-, 3-, 4-NO2
R
due to vibrations of the Ge
N bond [10, 11].
Compared to the spectra of the corresponding
ligands, the IR spectra of all complexes lack the bands
ν(OH) and ν(NH) in the region of 3220 to 3350 cm–1
and ν(C=O) at 1660 to 1680 cm–1. The bands due to the
ν(N–N) and ν(Ph–O) vibrations are shifted to the high-
frequency region by 20–30 cm–1 compared to similar
bands in the IR spectra of the ligands (970–980 and
1260–1270 cm–1, respectively) [12]. This indicates that
the ligands are present in the complexes in doubly
deprotonated form with formation of Ge–O bonds with
oxygen atoms of the oxyazine and deprotonated
hydroxo groups. The intense band at 670 cm–1 assigned
to stretching vibrations of the Ge–O bond appears
simultaneously in the IR spectra of the complexes [11].
Therefore, regardless of the position of the nitro
group in the molecules of the ligands, complexes with
the same structure are formed. The thermal stability and
intensity of the peak of germanium-containing ions in
the mass spectra of the complexes increase in the series
I–II–III.
REFERENCES
1. Lukevits, E.Ya., Biologicheskaya aktivnost’ soedinenii
germaniya (Biological Activity of Compounds of Ger-
manium), Riga: Zinatne, 1990, p. 129.
2. Johnson, D.K., Murphy, T.B., Rose, N.J., et al., Inorg.
Chim. Acta, 1982, vol. 67, no. 2, p. 159.
3. Pickart, L., Goodwin, W.H., Burgua, W., et al., Biochem.
Pharmacol., 1983, vol. 32, no. 24, p. 3868.
4. Smith, P.A.S., Organic Reactions, Adams, R., Ed., New
York: Wiley, 1947, vol. 3. Translated under the title
Organicheskie reaktsii, Moscow: Inostrannaya Lite-
ratura, 1951, vol. 3, p. 322.
1
We used the H and 13C NMR spectra of the com-
plexes and ligands to confirm the data obtained from IR
1
and UV spectroscopy. The H NMR spectrum of
2-NO2–H2L contains, along with a multiplet in an inter-
val of 6.900–8.181 ppm with an intensity of 8H (aro-
matic protons of both cycles), singlet signals at 8.5 (H–
C=N), 12.247 (HN–C=O), and 10.954 ppm (Ar–OH)
[13]. It is noteworthy that in the spectrum of complex I,
the last signal disappears and the singlet of the azome-
thine proton is shifted to the low field to 9.365 ppm.
The 13C NMR spectrum of complex I exhibits down-
field shifts of the following singlet signals of carbon
atoms of 2-NO2–H2L (δ, ppm): 148.326 (H–C=N),
161.160 (N–C=O), and 156.505 (CAr–OH) to 161.755,
163.969, and 161.160 ppm, respectively.
5. Gordon, A.J. and Ford, R.A., The Chemist’s Companion:
A Handbook of Practical Data, Techniques and Refer-
ences, NewYork: Wiley, 1972. Translated under the title
Sputnik khimika, Moscow: Mir, 1976, p. 440.
6. Shul’gin, V.F., Doctoral (Chem.) Dissertation, Simfe-
ropol: Simferopol State Univ., 1994, p. 293.
7. Klyuchnikov, N.G., Rukovodstvo po neorganicheskomu
sintezu (Manual on Inorganic Synthesis), Moscow:
Khimiya, 1965, p. 104.
The possible involvement of the nitro group of
2-NO2−H2L into coordination was ruled out because
the signal of carbon of the CAr–NO2 group at
147.20 ppm remains virtually unchanged during com-
plexation and appears in the 13C NMR spectrum of
complex I at 148.84 ppm. The coordination of the NO2
group in complexes II and III is still more improbable
because, in these cases, the formation of six- and seven-
membered metallocycles is energetically hindered com-
8. Nazarenko, V.V., Analiticheskaya khimiya germaniya
(Analytical Chemistry of Germanium), Moscow: Nauka,
1973, p. 116.
9. Nath, N. and Sharma, N., Synth. React. Inorg. Met.–Org.
Chem., 1990, vol. 20, no. 5, p. 623.
10. K. Nakanishi, Infrared Absorption Spectroscopy: Prac-
tical, Tokyo: Holden Day, 1962. Translated under the
title Infrakrasnye spektry i stroenie organicheskikh
soedinenii, Moscow: Mir, 1965, p. 31.
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 28 No. 1 2002

18
SEIFULLINA et al.
11. Seifullina, I.I., Cand. Sci. (Chem.) Dissertation, Odessa:
chemical Properties and Structure), Moscow: Nauka,
1990, p. 20.
Odessa State Univ., 1970, p. 154.
13. Zelenin, K.N., Khorseeva, L.A., Toshev, M.T., et al.,
Zh. Obshch. Khim., 1990, vol. 60, no. 11, p. 2550.
14. Seifullina, I.I., Shmatkova, N.V., Starikova, Z.A., and
Yanovskii, A.I., Zh. Neorg. Khim., 2000, vol. 45, no. 2,
p. 355.
12. Kogan, V.A., Zelentsov, V.V., Larin, G.M., and Lukov, V.V.,
Kompleksy perekhodnykh metallov s gidrazonami: fi-
ziko-khimicheskie svoistva
i stroenie (Complexes
between Transition Metals and Hydrazones: Physico-
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 28 No. 1 2002