Synthesis, spectral, magnetic, and thermal properties of Ge(IV) tetrachlorocobaltates complexes with 2-hydroxyarylaldehydes pyridinoyl(aminobenzoyl) hydrazones

Article abstract of DOI:10.1134/S1070363217010170

The interaction in the GeCl₄–nicotinoyl(isonicotinoyl, 2-, or 4-aminobenzoyl) hydrazone of 2-hydroxybenz(2-hydroxy-1-naphth)aldehyde (H₂L)–CoCl₂–methanol systems has resulted in the formation of [Ge(L·H)₂][CoCl<

Full text of DOI:10.1134/S1070363217010170

ISSN 1070-3632, Russian Journal of General Chemistry, 2017, Vol. 87, No. 1, pp. 107–116. © Pleiades Publishing, Ltd., 2017.
Original Russian Text © N.V. Shmatkova, I.I. Seifullina, V.G. Vlasenko, A.L. Trigub, S.I. Levchenkov, N.V. Khitrich, 2017, published in Zhurnal Obshchei
Khimii, 2017, Vol. 87, No. 1, pp. 113–122.
Synthesis, Spectral, Magnetic, and Thermal Properties
of Ge(IV) Tetrachlorocobaltates Complexes
with 2-Hydroxyarylaldehydes Pyridinoyl(aminobenzoyl) Hydrazones
N. V. Shmatkovaa*, I. I. Seifullinaa, V. G. Vlasenkob,
A. L. Trigubc, S. I. Levchenkovd, and N. V. Khitricha
a Mechnikov Odessa National University, ul. Dvoryanskaya 2, Odessa, 65082 Ukraine
*е-mail: nshmatkova@ukr.net
b Research Institute of Physics, Southern Federal University, Rostov-on-Don, Russia
c National Research Center “Kurchatov Institute,” Moscow, Russia
d Southern Scientific Center, Russian Academy of Sciences, Rostov-on-Don, Russia
Received March 3, 2016
Abstract—The interaction in the GeCl4–nicotinoyl(isonicotinoyl, 2-, or 4-aminobenzoyl) hydrazone of 2-hyd-
roxybenz(2-hydroxy-1-naphth)aldehyde (H2L)–CoCl2–methanol systems has resulted in the formation of
[Ge(L·H)2][CoCl4]·nCH3OH complexes with germanium chelates [Ge(L·H)2]2+ protonated at the exo chelate
nitrogen atom (NPy or NH2) as the cation. The type of electrolytic dissociation and character of thermolysis of
the complexes have been revealed. Spectral, thermal, and magnetic properties of the complexes have been studied.
Keywords: germanium(IV) complex, nicotinoyl hydrazone, pyridinoyl hydrazone, cobalt coordination compound
DOI: 10.1134/S1070363217010170
Heteronuclear complexes of metals possess a variety
of structures as well as utilitarian magnetic, catalytic,
and spectral properties [1]. Methods of their prepara-
tion are based on targeted molecular design (using
mononuclear complexes with vacant donor atoms capable
of binding with other metals and acting as bridging
ligand as building blocks), or self-assembly processes.
of physical and chemical methods including X-ray
diffraction analysis. The mentioned ligands are bound
with germanium in the hydrochloride form, revealing
tridentate cyclic coordination via OC–O, NCH=N, and OPh
atoms. This form is obtained due to the protonation of
vacant exo chelate nitrogen atoms NPy and NH2 groups
of hydrazide part of the hydrazones.
Regardless of the synthesis method, the ligands should
contain enough donor atoms to bind at least two
different metals and should be able to trigger the
specific ionic forms of mononuclear complexes and
form stable cationic-anionic structures with different
metals on their basis.
Hydrogen and metal atoms in a solution generally
compete for the binding with the donor atoms. There-
fore, we have suggested to use the above-mentioned
compounds as a basis for preparation of complexes
with different metals, in particular with cobalt(II).
We attempted two methods of the complexes
synthesis: the interaction of previously prepared above-
listed germanium(IV) complexes with cobalt chloride
in methanol and chemical self-assembly in the GeCl4–
hydrazone–CoCl2–methanol system. We established
the structure of the products and studied their magnetic,
thermal, and spectral properties.
We have earlier prepared germanium(IV) com-
plexes with β-, γ-pyridinoyl, and 2-aminobenzoyl hyd-
razones of 2-hydroxybenzaldehyde (β-H2Ns, γ-H2Is,
and 2-NH2-H2Bs, respectively) and 2-hydroxy-
naphthalene-1-carbaldehyde (β-H2Nnf, γ-H2Inf, and 2-
NH2-H2Bnf, respectively): [Ge(Ns·HCl)2], [Ge(Is·HCl)2]
[2, 3], [Ge(2-NH2-Bs·HCl)2] [4, 5], [Ge(Nnf·HCl)2],
[Ge(Inf·HCl)2] [6], [Ge(2-NH2-Bnf·HCl)2] [7]. and
comprehensively characterized them by means of a set
Using the first approach, we failed to isolate the
heterometal complexes regardless of the synthesis
107

108
SHMATKOVA et al.
Scheme 1.
O
C
O
C
O
+H+
Y
N
NH2
C
+
_H2O
C
N
N
X
Y
X
H
H
H
H
HO
X =
;
.
N
, H2N
Y =
,
,
,
N
NH2
HO
conditions [bubbling of gaseous hydrogen chloride,
varying of the Ge(IV) complex with hydrazone–СоCl2
molar ratio between 4 : 1 and 1 : 4, and altering the
solvent volume, temperature, and the nature of the exo
chelate atom of the ligand (Npy, NH2)]. That could be
likely due to the steric hindrance impeding the forma-
tion of the heterometal (Ge, Co) complexes via the
bridging by nitrogen atoms of bulky mononuclear
germanium(IV) complexes.
were isolated in quantitative yield after treatment of
complexes 1–6 with aqueous methanol at heating.
Products of stage-by-stage thermolysis of com-
plexes 1–6 were identified by means of thermal gravi-
metry (TG), differential thermal gravimetry (DTG),
and differential thermal analysis (DTA). The first stage
of complexes 1–6 thermolysis was marked by
endothermal effect at 80–160°С and was accompanied
by a mass loss corresponding to elimination of one (1–
4) or two (5, 6) moles of СН3ОН (Table 1). The
desolvation was further confirmed by isothermal
treatment of the complexes at 120 (2, 4) or 90°С (1, 5).
The residue contained 18.80 (1), 18.79 (2), 16.65 (4),
and 18.20 (5) wt % of chlorine, corresponding to
desolvated complexes 1 (2), 4, and 5 (calculated Cl, %:
18.82, 16.62, and 18.16%, respectively).
The second synthetic route afforded complexes 1–6
in high yields from the GeCl4–pyridinoyl (or amino-
benzoyl) hydrazone of 2-hydroxybenzaldehyde (or 2-
hydroxy-1-naphthaldehyde)–CoCl2–CH3OH systems,
if the conditions (see above) were properly chosen,
especially when the solvent volume was sufficient to
avoid intermediate crystallization of germanium(IV)
complexes. The elemental analysis data showed that
the Ge : Co : hydrazone : Cl molar ratio equaled 1 : 1 : 2 : 4
in the products irrespectively of composition of hyd-
razide and aldehyde parts of the hydrazone.
Analysis of the TG, DTG, and DTA data revealed
that thermal decomposition of the complexes occurred
in four stages (Table 1). The onset temperature of the
first stage was determined by the composition of the
hydrazide fragment of the ligand. For nicotinoyl
hydrazone, a single endothermal effect was observed
with a maximum at 290°С (1, 3), whereas for iso-
nicotinoyl and aminobenzoyl hydrazones two
endothermal effects were observed at 220–260 and
300–330°С (2, 4–6).
Nicotinoyl and isonicotinoyl hydrazones of 2-hyd-
roxybenzaldehyde (H2Ns, H2Is) and 2-hydroxy-
naphthalene-1-carbaldehyde (H2Nnf, H2Inf) as well as
2- and 4-aminobenzoyl hydrazones of 2-hydroxy-
benzaldehyde (2-NH2-, 4-NH2-H2Bs) were prepared as
described elsewhere [5, 6, 8] according to Scheme 1.
The Ge–Co–hydrazone–Cl molar ratio of 1 : 1 : 2 : 2
was found for the products of isothermal treatment of
the complexes at 220°С. Since Δm ≈ Δm(TG) ≈ Δmtheor
(–2НCl), that stage was assigned to elimination of two
moles of НCl, as confirmed by the reactions of the
evolving gas with AgNO3 solution (presence of
chloride) and KI solution (absence of Cl2).
Compounds 1–6 were crystalline substances,
readily soluble in DMF and DMSO (decomposing
within 24 h), moderately soluble in methanol (decom-
posing) and acetonitrile, and insoluble in acetone,
nitrobenzene, and chloroform. The measurement of elec-
troconductivity of freshly prepared solutions of com-
plexes 1–6 in DMF revealed that they were electrolytes
consisting of two ions (λ 60–75 Ω–1 cm2 mol–1) [9].
The complexes decomposed gradually with crystalliza-
tion of germanium(IV) compounds: [Ge(Ns)2], [Ge(Is)2],
[Ge(Nnf)2], [Ge(Inf)2] [5], [Ge(2-NH2-Bs)2], [Ge(4-
NH2-Bs)2] [4]. The same compounds (non-electrolytes)
At further heating, the complexes were stable up to
480–500°С (1–4) or 390–400°С (5, 6), their deeper
thermolysis (up to 740–890°С) being accompanied by
exothermal effects assigned to decomposition and
oxidation of organic part of the molecule (stages 2–4).
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SYNTHESIS, SPECTRAL, MAGNETIC, AND THERMAL PROPERTIES
Table 1. Study of thermal stability of complexes 1–6
109
Comp. no.
Temperature range (TG)
80–120
(tmax, °С)↑↓ (DTA)
100↓
Δm (TG), %
5.0
Δmcalc, %
4.07
Assignment
1
–СН3ОН
–2НCl
220–320
500–520
520–590
590–750
100–130
160–340
480–540
540–770
770–870
80–130
290↓
7.5
7.28
520↑
37.5
12.5
7.5
570↑
740↑
2
3
4
5
6
120↓
5.5
4.07
7.28
–СН3ОН
–2НCl
250↓; 330↓
520↑; 540↑
610↑
8.2
28.0
18.0
12.0
3.5
840↑
120↓
3.6
–СН3ОН
–2НCl
130–320
480–520
520–600
600–840
80–160
290↓
8.3
8.23
470↑; 520↑
560↑; 580↑
810↑
33.3
13.3
8.3
150↓
4.0
3.6
–СН3ОН
–2НCl
220–310
480–550
550–640
640–790
70–110
260↓; 300↓
520↑
8.0
8.23
42.0
16.0
8.0
560↑
770↑
90↓
8.3
7.57
8.62
–2СН3ОН
–2НCl
140–310
390–670
670–860
860–970
70–110
220↓; 310↓
650↑
7.5
31.7
35.0
8.3
800↑; 840↑
890↑
90↓
6.6
7.57
8.62
–2СН3ОН
–2НCl
210–340
400–550
550–710
710–910
250↓; 310↓
500↑
10.0
28.3
26.7
15.0
580↑
840↑
In view of the elemental analysis, electroconduc-
tivity, and thermogravimetry data, the following
formulas were suggested for the prepared complexes:
[Ge(Ns·H)2][CoCl4]·CH3OH (1), [Ge(Is·H)2][CoCl4]·
CH3OH (2), [Ge(Nnf·H)2][CoCl4]·CH3OH (3),
[Ge(Inf·H)2][CoCl4]·CH3OH (4), [Ge(NH2-Bs·H)2]·
[CoCl4]·2CH3OH, where 2-NH2- (5), 4-NH2- (6).
Further comprehensive studies confirmed their validity.
IR spectra of complexes 1–6 were assigned by analogy
with those of the corresponding germanium(IV)
complexes, [Ge(Inf·HCl)2] and [Ge(2-NH2-Bs·HCl)2];
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 87 No. 1 2017

110
SHMATKOVA et al.
Table 2. IR spectroscopy data (cm–1) of mononuclear complexes of germanium(IV) and compounds 1–6
ν(>C=N–
N=C<)
1604
δ(PyH)
[δ(NH3+]
418, 1020
Compound
ν(С=С)ring
δ(NCО)
ν(N–N)
ν(Ge–O) ν(Ge←N)
[Ge(Inf·HCl)2]
1583
1549
1548
1547
1549
1548
1551
1550
1551
1035
1034
1033
1034
1074
1035
1033
1033
658
674
683
683
679
688
686
687
616
616
614
615
617
620
619
620
1
1608
1607
415, 998
417, 1003
420, 1010
420, 1004
[1623]
2
3
1606
1603
1602
1608
1610
1600
1597
1580
1580
1581
4
[Ge(2-NH2-Bs·HCl)2]
5
6
[1620]
[1623]
structures of the latter have been earlier elucidated by
X-ray diffraction analysis [5, 6] (Table 2). Coor-
dination unit of germanium typical of mononuclear
Ge(IV) compounds was retained in complexes 1–6, as
indicated by the absence of the ν(ОН), ν(NH), and
ν(С=О) bands (observed in the spectra of starting
hydrazones at 3430–3420, 3260–3190, and 1680–
1665 cm–1); the presence of the band of oxyazine
(N=С–О) group stretching vibrations at 1547–1550 cm–1
[10] instead of the δ(NН) band in the spectra of
hydrazones (1570–1560 cm–1); and the appearance of
the ν(Ge–O) and ν(Ge<N) bands at ~680 and 620 cm–1
evidencing the ligands coordination via nitrogen atoms
of azomethine group and oxygen atoms of oxyazine
and hydroxy groups [3–6].
practically identical to that of the parent hydrazones
(1027–1030 cm–1) thus confirming the localization of
the N–N bond found by means of X-ray diffraction
analysis for [Ge(Inf·НCl)] and [Ge(2-NH2-Bs·НCl)2].
The coordination polyhedrons of cobalt(II) in
complexes 1–4 were determined using diffuse reflec-
tance spectroscopy and effective magnetic moment
(μeff) data (Table 3). Visible and near-IR regions of the
diffuse reflectance spectra of the complexes contained
two broad bands with the multiplet structure and
energy independent of the hydrazone composition
4
4
(Table 3). The А2g→4T1g(F) and А2g→4T1g(P) elec-
tron transitions evidenced the tetrahedral structure of
the [CoCl4]2– polyhedron [12, 13]. That was also
confirmed by the μeff values (4.01–4.38 µB at room
temperature, Table 3) corresponding to the high-spin
state of cobalt(II). The measured μeff values exceeded
those for the purely spin character (3.87 µB). That was
due to the spin-orbital interaction leading to the mixing
of the ground state 4А2 with the excited magnetic state,
the latter being relatively low in energy for tetrahedral
Со(II) complexes [14].
At the same time, the spectra of compounds 1–4
contained a strong band of skeletal vibrations of the
>C=N–N=C< fragment at 1603–1608 cm–1, pointing at
delocalization of the С=N bonds, similarly to
[Ge(Inf·НCl)2] [6] owing to the formation of enol form
of the ligand. Frequencies of the pyridine ring
vibrations in those compounds were by 10–12 cm–1
higher than those in the corresponding hydrazones
(400 and 997–1000 cm–1) confirming the protonation
of the exo chelate nitrogen atoms [3, 6, 8].
The similar nearest surrounding of germanium and
cobalt ions in complexes 1–6 was confirmed by
analysis of XANES spectra of K-edges of Co and Ge.
Indeed, as shown in Fig. 1, the shape and parameters
of XANES of K-edges of Co and Ge as well as their
first derivatives were close for the studied compounds.
The spectra of complexes 5, 6 additionally
contained a δ(NH3+) band [4, 11] at 1608–1623 cm–1,
evidencing the protonation of the amino group of the
hydrazide fragment. That was also confirmed by the
appearance of the νas/s(NH) bands of the NH3+ group at
3054–3050 cm–1 [4, 11].
The shape of the K-edge of Ge was determined by
the dipole electron transition 1s→4p corresponding to
the main maximum С of the absorption spectrum.
Maxima D and E were determined by the nearest
surrounding of the absorbing germanium atom. The
The ν(N–N) band at ≈1035 cm–1 in the spectra of
the prepared complexes (except for compound 4) was
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SYNTHESIS, SPECTRAL, MAGNETIC, AND THERMAL PROPERTIES
(a)
111
(b)
μ, a.u.
μ, a.u.
Е, eV
Е, eV
Fig. 1. XANES spectra of K-edges of absorption of Ge for complexes 1, 2, 4–6 (a) and the corresponding first derivatives of the
edges (b).
presence of a narrow strong peak C of the K-edge of
Ge and a single narrow maximum of the first
derivative of the edge pointed at the highly sym-
metrical octahedral surrounding of germanium atoms
in the studied compounds. Since the 3d atomic orbital
of Ge was fully occupied, a noticeable hybridization in
those compounds was impossible, as confirmed by the
absence of the pre-edge structure.
EXAFS of both edges in the studied complexes, and
parameters of the nearest surrounding of the metal ions
are collected in Tables 4 and 5.
From the data in Fig. 3 it is seen that FTM of
EXAFS of K-edges of Ge for the studied samples
contained a major peak, r 1.45–1.48 Å, and the peaks
with lower magnitude at larger r. The major peak for
the studied samples corresponded to the scattering of
photoelectron wave at the six nearest atoms of nitrogen
and oxygen of the ligands, constituting the first
coordination sphere. The first coordination sphere was
fitted by two spheres; since the difference in the
scattering amplitudes of nitrogen and oxygen was
similar, it was impossible to separate their contribu-
tions. The thus obtained parameters of the first
In contrast to K-edge of Ge, XANES of K-edges of
Co (Fig. 2) contained strong pre-edge peaks A at
7711.5 eV, corresponding to the 1s→4d electron
transitions. These transitions were restricted by the
selection rules; therefore, the transition probability was
mainly determined by the p–d-hybridization of the
metal atomic orbitals. The latter was most efficient for
the complexes containing no inversion center with
respect to the metal. The presence of strong pre-edge
structure A in XANES of K-edges of the Co
complexes and additional maxima B at the edge as
well as splitting of the first derivative was typical of
tetrahedral surrounding of cobalt ions.
Table 3. Electron transitions energy and effective magnetic
moments of complexes 1–4
Electron transition, cm–1
ν2 – 4А2g→4T1g(F) ν3 – 4А2g→4T1g(P)
Comp.
no.
μef, µB
Parameters of local atomic surrounding of
germanium and cobalt ions in the complexes were
elucidated by analysis of EXAFS of Cо and Ge K-
edges of X-ray absorption spectra. Figures 3 and 4
display the Fourier transform magnitudes (FTM) of
1
2
3
4
6095–4937
6096–4889
6098–4902
6096–4866
15954–14384
15895–14289
15896–14400
15890–14471
4.38
4.24
4.14
4.01
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112
SHMATKOVA et al.
FTM, a. u.
(a)
μ, a.u.
1
r, Å
2
4
Е, eV
(b)
μ, a.u.
r, Å
r, Å
5
6
Е, eV
Fig. 2. XANES spectra of K-edges of absorption of Со for
complexes 1, 2, 4–6 (a) and the corresponding first
derivatives of the edges (b).
r, Å
coordination sphere for the studied samples were close.
The second peak in FTM was assigned to the distance
to the second coordination sphere constituted by carbon
atoms of the ligand.
r, Å
The FTM of EXAFS of K-edges of Со contained a
single main peak, r 1.79–1.83 Å, its magnitude being
close for the studied samples (Fig. 4). The local atomic
surrounding coincided well with the model assuming
surrounding of cobalt by four chlorine atoms. The
Co···Cl distance was identical for the studied samples
(within the determination accuracy 0.02 Å).
Fig. 3. FTM of EXAFS of K-edges of absorption of Ge for
complexes 1, 2, 4–6 [(circles) for theory, (solid line) for
experiment].
rounding of the metal atoms in compounds 1–6
(Scheme 2).
In summary, the conditions of self-assembly of the
reactants in the presence of sufficient amount of
hydrogen chloride formed in the reaction favored the
The results of EXAFS analysis were in good
correspondence with XANES data for those com-
pounds and confirmed the stated identical local sur-
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SYNTHESIS, SPECTRAL, MAGNETIC, AND THERMAL PROPERTIES
formation of tetrachlorocobaltates(II) containing the
113
FTM, a. u.
corresponding mononuclear germanium complexes
with the ligand protonated at the exo chelate nitrogen
atom (NPy- or NH2) as the cation.
1
2
EXPERIMENTAL
Diffuse reflectance spectra were registered using a
Lambda-9 spectrophotometer (Perkin-Elmer), using
MgO (βMgO 100%) as the reference. IR absorption
spectra (4000–400 cm–1, KBr pellets) of the ligands
and the complexes were recorded using a Shimadzu
FTIR-8400S spectrometer.
r, Å
Cobalt content was determined by complexometric
titration [15]; germanium content was determined by
potentiometric titration [16] and atomic emission
spectroscopy with inductively coupled plasma (a
Perkin Elmer Optima 2000 DV instrument). Carbon,
hydrogen, and nitrogen content was determined using a
Flash EA 1112 CHN-analyzer; chlorine content was
determined using Schöniger method [17].
r, Å
4
Thermogravimetric studies were performed using a
Q-derivatograph of the Paulik–Paulik–Erdey system
(heating in air, 20–1000°С at 10 deg/min rate, spe-
cimen mass 100 mg, open platinum crucible, annealed
alumina as a reference). The solvate composition of
the complexes was determined by isothermal treatment
of the specimens at temperature corresponding to onset
of the respective stage found by means of DTA (TG)
analysis, followed by elemental analysis of the
thermolysis products.
Specific resistance of 10–3 mol/L solutions of com-
pounds in DMF was determined using an Ekonomiks–
ekspert digital device, the electrolyte type was deter-
mined from the reference tables [9].
r, Å
5
r, Å
6
Specific magnetic susceptibility of complexes 1–4
in the solid state at room temperature was determined
by relative Faraday method in 9 kOe magnetic field
with Hg[Co(CNS)4] as the reference. The molar mag-
netic susceptibility (χМ) was determined correcting for
the atoms diamagnetism via the additive Pascal
scheme [18]. Effective magnetic moment was cal-
culated using the following equation:
r, Å
Fig. 4. FTM of EXAFS of K-edges of Со absorption for
complexes 1, 2, 4–6 [(circles) for theory, (solid line) for
experiment].
X-ray K-edges of absorption of solid Ge and Co
complexes were obtained in the transmission mode of
EXAFS spectrometer (“Structural Material Science”
station, Kurchatov Synchrotron Center, Moscow).
Energy of the electron beam (source of X-ray
synchrotron radiation) was 2.5 GeV at a current of 80–
3k
N
µeff
=
—–µB χT ≈ √8χT,
(1)
√
with k, the Boltzmann constant; N, the Avogadro
number; μВ, Bohr’s magneton.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 87 No. 1 2017

114
SHMATKOVA et al.
Table 4. Parameters of local atomic surrounding of germanium
atoms in complexes 1, 2, 4–6 determined by multisphere
fitting of EXAFS data of K-edges of Ge absorptiona
Table 5. Parameters of local atomic surrounding of cobalt
ions in complexes 1, 2, 4–6 determined by multisphere
fitting of EXAFS data of K-edges of Со absorptiona
Comp.
no.
Comp.
no.
N
4
r, Å
2.27
2.26
2.26
2.25
2.23
σ2, Å2
0.0042
0.0040
0.0042
0.0055
0.0055
Atom Qb, %
N
r, Å
σ2, Å2
Atom
Qb, %
Cl
Cl
Cl
Cl
Cl
0.07
0.04
0.2
1
1
4
2
2
1.88
1.94
2.70
0.0033
0.0033
0.0033
O/N
O/N
C
0.5
4
2
4
5
6
4
2
4
5
6
4
2
2
1.88
1.96
2.70
0.0028
0.0028
0.0028
O/N
O/N
C
0.4
1.6
0.5
2.2
4
0.04
2.2
3.2
4
2
2
1.87
1.93
2.69
0.0028
0.0028
0.0028
O/N
O/N
C
a
r, interatomic distance; N, coordination number; σ, Debye–
Waller factor; Q, goodness of fit function. b Δr = 1.194–2.1384 Å.
4
2
2
1.88
1.94
2.70
0.0033
0.0033
0.0033
O/N
O/N
C
and atomic coordinates for the structurally similar com-
pounds elucidated by X-ray diffraction [5, 6].
Number of the parameters varied during the multi-
sphere fitting never exceeded the number of inde-
pendent parameters Nind that could be reliably deter-
mined from the experimental EXAFS spectrum within
the given Δk and Δr ranges:
4
2
2
1.86
2.01
2.68
0.0028
0.0028
0.0028
O/N
O/N
C
a
r, interatomic distance; N, coordination number; σ2, Debye–
Waller factor, Q, goodness of fit function. b Δr = 1.032–1.874 Å.
Nind = (2ΔrΔk/π) + 1,
(2)
100 mA. The X-ray radiation was monochromatized
using a double-crystal Si(111) monochromator. A solid
specimen of the complex was placed between thin
Lavsan films. X-ray absorption spectra were processed
via conventional procedures [19] including back-
ground correction, normalization by the K-edge jump,
separation of atomic absorption µ0, and Fourier trans-
formation of the obtained EXAFS (χ)-spectra in the
photoelectrons wave vector range of k 3.0 to 13.0 Å–1
with cubic weight function k3. The so determined
Fourier transform magnitudes (FTM) were pseudo
radial functions of atoms distribution around the
absorbing atoms (cobalt and germanium) accounting to
the phase corrections. The threshold ionization energy
E0 was chosen from the maximum of the first
derivative of the K-edge and then varied during fitting.
with Δk, analyzed range of EXAFS spectrum in the
photoelectron wave vector space; Δr, region of the
R-space taken for Fourier filtration.
The fitting procedure presumed minimization of the
goodness of fit function Q:
Σ[kχexp(k) – kχth(k)]2
Q(%) = —————————×100%.
(3)
Σ[kχexp(k)]2
Germanium(IV) chloride (specially pure grade,
d 1.89 g/cm3) and organic solvents of (specially pure
grade) were used. Cobalt(II) chloride was obtained via
dehydration of the crystal hydrate CoCl2·6H2O (spe-
cially pure grade) at 140°С.
Purity of nicotinoyl and isonicotinoyl hydrazones
of 2-hydroxybenzaldehyde (H2Ns, H2Is) and 2-hyd-
roxynaphthalene-1-carbaldehyde (H2Nnf, H2Inf) as
well as 2- and 4-aminobenzoyl hydrazones of 2-hyd-
roxybenzaldehyde (2-NH2-, 4-NH2-H2Bs) was moni-
tored by TLC on Silufol UV-254 plates using 1 : 10
chloroform–acetone (H2Ns, H2Is, 2-NH2-H2Bs) and
20 : 1 chloroform–methanol (H2Nnf, H2Inf, 4-NH2-
H2Bs) mixtures as eluents. The prepared compounds
were identified by their melting points.
Precise structural parameters of nearest surrounding
of cobalt and germanium atoms in compounds 1, 2, 4–
6 were determined by means of nonlinear fitting of the
respective coordination spheres parameters until
coincidence of the calculated EXAFS signal and that
extracted from the full EXAFS spectrum by Fourier
filtration, as implemented in IFFEFIT-1.2.11 software
package [20]. Phases and amplitudes of the photo-
electron wave required for calculation of the model
spectrum were determined using FEFF7 software [21]
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 87 No. 1 2017

SYNTHESIS, SPECTRAL, MAGNETIC, AND THERMAL PROPERTIES
115
Scheme 2.
O
O
Cl
Co
Cl
O
O
N
N
Ge
O
N
N
Co
Ge
O
N
N
Cl
Cl
Cl
Cl
Cl
N
Cl
N
O
O
HN
HN
NH
NH
1, 2
3, 4
O
Cl
Co
O
N
Ge
O
N
N
Cl
Cl
Cl
N
O
HN
NH
5, 6
β-NH+ (1), γ-NH+ (2), β-NH+ (3), γ-NH+ (4), 2-NH3+ (5), 4-NH3+ (6).
Preparation of complexes 1–6 (general procedure).
To a hot solution of 2×10–3 mol of a ligand in 15 (2-
NH2-H2Bs, 4-NH2-H2Bs, H2Ns), 75 (H2Nnf, H2Inf), or
20 mL (H2Is) of methanol was added at stirring
0.24 mL of GeCl4. The obtained solution was kept
during 10 min at 50°С, and then a solution of 2×
10–3 mol of cobalt(II) chloride in methanol was added.
In the case of complexes 3 and 4, the formed
precipitate was separated after cooling the mixture to
ambient temperature. For isolation of other complexes,
the solution was additionally kept at about 50°С during
10 min and left for crystallization. The precipitate was
separated, washed with anhydrous methanol (2×5 mL),
and dried at 80°С to a constant mass. Yield 73–85%.
41.11; Н 3.04; Со 7.62; Сl 18.08; Ge 9.24; N 10.69. М
788.
Complexes 3, 4. Found, %: С 47.45, 47.35; Н 3.18,
3.19; Со 6.61, 6.70; СI 16.05, 16.04; Ge 8.20, 8.19; N
9.44, 9.52. C35H28Cl4CoGeN6O5. Calculated, %: С
47.40; Н 3.16; Со 6.65; СI 16.04; Ge 8.20; N 9.49. М
886.
Complexes 5, 6. Found, %: C 42.58, 42.57; Н 3.80,
3.78; Со 6.72, 6.99; Сl 16.80, 16.79; Ge 8.60, 8.56; N
9.95, 9.97. C30H32Cl4CoGeN6O6. Calculated, %: С
42.55; Н 3.78; Со 7.09; Сl 16.79; Ge 8.59; N 9.93. М
846.
ACKNOWLEDGMENTS
Complexes 1, 2. Found, %: С 41.14, 41.17; Н 3.06,
3.08; Со 7.54, 7.49; Сl 18.10, 18.07; Ge 9.20, 9.21; N
10.71, 10.74. C27H24Cl4CoGeN6O5. Calculated, %: С
This work was performed using the equipment of
Unique Science Installation “Kurchatov Source of
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 87 No. 1 2017

116
SHMATKOVA et al.
Chem., 1981, vol. 20, p. 2794. doi 10.1021/ic50223a012
Synchrotron Radiation” financed by Ministry of Educa-
tion and Science of Russian Federation (project
identifier RFMEFI61914X0002) and was financially
supported by Southern Federal University (project
no. 213.01-07-2014/11PChVG “Peculiarities of electronic
structure of elements with vacant shells”).
11. Nakamoto, K., Infra-Red Spectra of Inorganic and
Coordination Compounds, New York: John Willey and
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1976, vol. 21, no. 8, p. 2003.
14. Drago, R., Fizicheskie metody v khimii (Methods in
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