Cobalt(II) and nickel(II) complexes with 1-amino-8-hydroxynaphthalene-2,4- disulfonic acid in condensation reactions with aromatic carbonyl derivatives

Article abstract of DOI:10.1134/S1070328407020108

The condensation reaction of cobalt(II) and nickel(II) complexes with 1-amino-8-hydroxynaphthalene-2,4-disulfonic acid and aromatic carbonyl compounds (benzoin and 2-hydroxy-1-naphthaldehyde) was carried out. Four new complexes (I-IV) were synthesized. Th

Full text of DOI:10.1134/S1070328407020108

ISSN 1070-3284, Russian Journal of Coordination Chemistry, 2007, Vol. 33, No. 2, pp. 130–135. © Pleiades Publishing, Ltd., 2007.
Original Russian Text © L.S. Skorokhod, I.I. Seifullina, V.G. Vlasenko, I.V. Pirog, 2007, published in Koordinatsionnaya Khimiya, 2007, Vol. 33, No. 2, pp. 135–140.
Cobalt(II) and Nickel(II) Complexes with 1-Amino-8-
Hydroxynaphthalene-2,4-Disulfonic Acid in Condensation
Reactions with Aromatic Carbonyl Derivatives
L. S. Skorokhoda, I. I. Seifullinaa, V. G. Vlasenkob, and I. V. Pirogb
a Mechnikov University, ul. Petra Velikogo 2, Odessa, 270100 Ukraine
b Research Institute of Physics, Rostov State University, pr. Stachki 194, Rostov-on-Don, 344104 Russia
Received February 20, 2006
Abstract—The condensation reaction of cobalt(II) and nickel(II) complexes with 1-amino-8-hydroxynaphtha-
lene-2,4-disulfonic acid and aromatic carbonyl compounds (benzoin and 2-hydroxy-1-naphthaldehyde) was
carried out. Four new complexes (I–IV) were synthesized. The compounds were identified by elemental anal-
ysis, powder X-ray diffraction, thermogravimetry, magnetic susceptibility, IR and diffuse reflection spectros-
copy, and EXAFS. The spatial arrangement of the donor centers of the ligands in the coordination units (tetra-
hedral for I, octahedral for II and III, and square planar for IV) was determined.
DOI: 10.1134/S1070328407020108
It is known that complexes in which ligands are
coordinated to the metal through nitrogen of the pri-
mary amino group can be used as the starting com-
pounds in condensation reactions. It has been shown
[1–5] that these reactions may give rise to metal che-
lates with various structures and properties.
Previously [6], Co(II) and Ni(II) complexes with
1-amino-8-hydroxynaphthalene-2,4-disulfonic acid
were synthesized and studied by a number of physico-
chemical methods; structures of these complexes were
proposed (A, B, and C)
EXPERIMENTAL
Compounds A, B, and C synthesized by a known
procedure [6] and reagent grade benzoin
(C6H5CH(OH)C(O)C6H5) and 2-hydroxy-1-naphthal-
dehyde were used.
Hot saturated aqueous solutions of complexes A, B,
and C (0.005 mol in 100 ml) were mixed with ethanol
solutions of BENZ or HNA. The mixtures (A +
0.001 mole of BENZ in 50 ml (I), B + 0.005 moles of
BENZ in 30 ml (II), A + 0.01 moles of HNA in 70 ml
(IV), C + 0.005 moles HNA in 35 ml (III)) were
refluxed on a water bath for 2 h. After cooling, the
resulting precipitates I–IV were filtered off, washed
with ethanol and ether, and dried over anhydrous CaCl2
to a constant weight.
H O
Ni/
2
2
HO
H N
2
O
Co/
2
SO
3
KO S
NH
2
3
Analysis for cobalt and nickel was carried out by
X-ray fluorescence spectroscopy on a Spark-1 spec-
trometer with a copper radiation (12 kV, 10 mA) at a
counting rate of 400 pulses per second.
SO K
3
SO K
3
(A)
(B)
OH
X-Ray diffraction patterns were measured on a
DRON-05 diffractometer on an iron anticathode. The
interplanar spacing were determined from tables [7].
H O
2
2
O
Co/
2
CH COO
Thermogravimetric analysis was carried out on a
Paulik–Paulik–Erdey Q-derivatograph in a static air
atmosphere in the temperature range of 20–500°ë; the
heating rate was 10 K/min and α-Al2O3 was used as the
standard.
3
KO S
NH
2
3
H O
2
SO K
3
(C)
IR spectra were recorded in the 400–4000 cm−1
range on a Specord 75IR instrument (KBr pellets). The
diffuse reflection spectra (DRS) were recorded on a
To continue these works, here we studied the behav-
ior of complexes A, B, and C in the condensation reac-
tions with α-hydroxy-α-phenylacetophenone (benzoin,
BENZ) and 2-hydroxy-1-naphthaldehyde (HNA). The Specord M40 spectrometer in the 12000–30000 cm–1
products formed in these reactions are examined.
range with MgO as the standard.
130

COBALT(II) AND NICKEL(II) COMPLEXES
131
Table 1. Results of elemental analysis and some characteristics of complexes I–IV
Content (found/calculated)
Molar
Com-
electrical con-
ductivity.
Color Molecular formula
pound
C
H
N
S
M (II)
H2O
Ω
–1 cm2 mol–1
I
Dark C34H24N2O14S4Ni
brown
46.06/46.84 2.69/2.76 3.30/3.22 14.83/14.70 6.92/6.77
12.3
II*
III
IV
Dark C34H26N2O16S4K2Co 41.13/41.51 2.53/2.64 2.71/2.85 13.18/13.02 5.84/6.00 3.74/3.66
violet
128.8
10.7
14.2
Pale C21H18NO11S2Co
green
43.61/43.22 3.00/3.09 2.19/2.40 10.71/10.97 10.04/10.12 9.12/9.26
45.84/46.07 2.49/2.56 2.43/2.56 11.54/11.70 10.58/10.79 3.43/3.29
Bright C21H14NO9S2Ni
green
* K (found/calculated): 7.78/7.94 %.
The molar electrical conductivity was calculated by as r = R – α, where α is the linear section of the phase
measuring the active resistivity of the millimolar solu- shift. The amplitudes of the FTM peaks are propor-
tions of I–IV in DMF by an E 7–8 digital meter within tional to the coordination numbers. The precise param-
0–10 mΩ in an Arrhenius vessel. The magnetic suscep- eters for the structure of the local environment of the
tibility was determined by the Gouy method at 293 K. metal atoms were determined by non-linear fitting of
Hg[Co(NCS)4] was used as the standard for calibration. the parameters of the corresponding coordination
spheres via comparison of the simulated EXAFS signal
Cobalt K-edge X-ray absorption spectra were
and the FTM isolated from the full EXAFS spectrum by
obtained in the transmission mode on EXAFS spec-
Fourier filtration. This non-linear fitting was carried out
trometer at the Siberian Synchrotron Center (Novosi-
using the IFFEFIT-1.2.5 program package [9]. The
birsk). The energy of the electron beam used as the
phases and amplitudes of the photoelectron wave scat-
source of X-ray synchrotron radiation was 2 GeV at an
tering were calculated using the FEFF7 program [10].
average current of 80 mA. The X-radiation was mono-
Complexes of the same metals with a similar structure
chromatized using a two-crystal Si(III) monochroma-
and with known X-ray diffraction data were used as
tor. The intensities of the incident and transmitted
model species.
X-radiation were recorded by argon-filled ionization
chambers.
The fitting quality function (Q) which was mini-
mized to find parameters of the structure of the nearest
environment was calculated from the formula
Samples for recording the EXAFS spectra were
thoroughly mixed with Apiezon and placed between
thin Dacron films. The sample thickness was selected in
such a way that the intensity of the transmitted X-rays
decreased 2.5–3.0-fold. After standard background
subtraction, normalization to the ä-edge jump, and
atomic absorption µ0 subtraction [8], fourier transform
of the resulting EXAFS (χ)-spectra was carried out in
the range of the wave vectors of photoelectrons k from
2.6 to 13.3 Å–1 with the weight function k2. The thresh-
old ionization energy Ö0 was chosen from the maxi-
mum of the first derivative of the ä-edge and was fur-
ther varied during the fitting.
[kχexp(k) – kχth(k)]2
∑
---------------------------------------------------------
Q(%) =
100,
[kχexp(k)]2
∑
where k is the wave vector of photoelectrons, χexp is the
experimental EXAFS function isolated from the
absorption spectrum, χth is the theoretical EXAFS func-
tion calculated by varying the structural parameters of
the local atomic environment of the absorbing atom.
The Fourier transform modulus (FTM) obtained
after the Fourier transform of the EXAFS spectrum
reflects the radial distribution function of the neighbor-
RESULTS AND DISCUSSION
Complexes I–IV (Table 1) were synthesized by the
ing atoms around the absorbing metal atom. The reaction of benzoin and 2-hydroxy-1-naphthaldehyde
x-coordinates of the FTM peaks (r) are related to the with Ni(II) (A) and Co(II) (B, C) complexes synthe-
radii (R) of the coordination spheres of the metal atoms sized previously [6].
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 33 No. 2 2007

132
Table 2. X-Ray diffraction patterns of complexes I–IV
II
SKOROKHOD et al.
I
III
IV
d, Å
I/I0, %
d, Å
I/I0, %
d, Å
I/I0, %
d, Å
I/I0, %
9.93
8.96
4.96
4.50
3.92
3.31
98
98
3.51
3.99
4.09
4.48
89
56
18.3
5.97
5.06
4.61
3.61
100
32
43
39
23
6.01
5.12
4.61
3.61
2.84
41
100
86
66
100
71
98
42
100
39
16
Table 3. Assignment of the key vibration frequencies (cm–1) in the IR spectra of complexes A, B, and C and I–IV
Com-
pound*
ν(OH) + ν(NH2) ν(C=N)
δ(NH2)
δ(H2O)
ν(SO2)
ν(C–O)
ν(M–N)
ν(M–O)
A
3500, 3300
1605
1230, 1080, 1060
1230, 1080, 1060
1230, 1080, 1060
1270, 1160, 1030
1270, 1160, 1030
1270, 1160, 1030
1270, 1160, 1030
590
620
640
595
620
590
650
520
520
520
525
525
520
514
I**
IV
3300
3600–3400, 3300
3600–3340
3600–3400
3600–3400
3600–3400
1580
1541
1644
1610
1630
1630
1187
B
1570
1570
II**
C***
III
1540
1540
1644
1184
–1
–1
* ν(C=O) = 1680 (BENZ); 1690 cm (HNA); ν(C–O) = 1210 cm (BENZ, HNA).
–1
** ν(N–H) = 3350; δ(NH) = 1485; ν(C–N) = 1250 cm .
*** ν (COO ) = 1580 cm ; ν (COO ) = 1415 cm .
–
–1
–
–1
as
s
Powder X-ray diffraction confirmed the individ- spectra of I–IV do not contain bands typical of NH2 and
ual character of the compounds (Table 2). Com-
plexes I–IV are stable in air, soluble in DMF and
DMSO, and insoluble in water. The electrical con-
ductivity (Table 1) of the complexes indicates that I,
III, and IV are nonelectrolytes, while II is a three-
ion electrolyte (this is due to the presence of two
potassium cations in the complex).
C=O vibrations but contain a new band corresponding
to stretching vibrations of the azomethine group. Thus,
the condensation involves the coordinated amino group
of the acid and the carbonyl fragment of BENZ or HNA
without cleavage of the M
N coordination bond, as
the ν(M−N) absorption band is retained (Table 3).
In the case of complexes I and II, binding of the
complexing metal to the azomethine nitrogen seems to
have promoted an additional condensation of the ben-
zoin hydroxy group and the amino group of the second
ligand in A and B. This conclusion was drawn from the
fact that the lack of the benzoin ν(C=O) and ν(C–O)
bands in the IR spectra of complexes I and II is accom-
panied by the appearance of a new absorption band typ-
ical of a secondary amino group (Table 3). In com-
The data of elemental analysis and thermogravime-
try show that compounds II, III, and IV contain 2, 3,
and 1 water molecules, respectively, which are elimi-
nated at 150, 170, and 150°C. This attests to their inner-
sphere position and is in line with IR data (Table 3).
Complexes I–IV melt with decomposition in a temper-
ature range of 250–330°ë.
A comparison of the IR spectra of initial A with I
and IV, B with II, and C with III has shown that the IR plexes I and II, the bonds with the oxygen atoms (from
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 33 No. 2 2007

COBALT(II) AND NICKEL(II) COMPLEXES
133
the sulfo group in I and the deprotonated hydroxy
I, arb. u.
group in II) are retained, as indicated by invariable
positions of the respective stretching bands in the IR
spectra.
Complex I is paramagnetic. The effective magnetic
moment (Table 4) suggests its tetrahedral structure. The
DRS of this complex is also well interpreted in terms of
a tetrahedral symmetry (Table 4) [11]. Complex II has
an octahedral structure (relying on the magnitude of its
magnetic moment and the DRS) (Table 4) [12].
On the basis of the foregoing and in view of the
energetic favorability of the formation of three conju-
gated metal rings in I and II, the most probable struc-
tural formulas of these compounds were proposed:
1.2
1.0
0.8
0.6
0.4
0.2
0
–0.2
–0.4
7600
7700
7800
7900
E, eV
HO
Fig. 1. Near-edge X-ray absorption fine structure (XANES)
of the cobalt K-edge spectrum of complex III (solid line)
and the first derivative of the edge (dashed line).
C H
6
5
HC
SO H
HN
3
C H
6
5
C
Ni
SO
In complex III, as in II, the metal coordination poly-
hedron is an octahedron. The inner sphere of the com-
plexing metal retains three coordinated water mole-
cules present in the initial complex C. The Co(II) coor-
dination number is supplemented to six due to the
tridentate coordination of the condensation product
through the azomethine nitrogen and two oxygen atoms
of the deprotonated hydroxy groups of the aldehyde
and acid fragments. This conclusion was drawn from
the whole set of data from elemental analysis, thermo-
gravimetry (Table 1), IR spectroscopy (Table 3), DRS,
and magnetic susceptibility measurements (Table 4).
3
OH
N
SO
3
(I)
HO S
3
C6H5
SO3K
H5C6
KO3S
OH2
Co
HO3S
N
HN
SO3H
The spatial arrangement of the electron-donor cen-
ters in III was established in the EXAFS study.
Figure 1 shows the fine X-ray absorption near-edge
structure (XANES) of the cobalt ä-edge spectrum and
O
O
OH2
(II)
Table 4. Electron transition energies and effective magnetic moments for complexes I–IV
Electron transition, cm–1
Compound
µeff, µB (T = 293 K)
ν1
ν2
ν3
Inactive
3T1(F)
8620
4T1g(F)
3A2
3T1(F)
3T1(P)
I
15873
3.76
4T1g(F)
4T2g(F)
4A2g
4T1g(F)
4T1g(P)
II
8695
8241
18094
18118
20031
20000
5.11
5.32
III
1A1g
1A2g
1A1g
1B2g
1A1g
23000
Eg
IV
17600
20140
0
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 33 No. 2 2007

134
SKOROKHOD et al.
FTM, arb. u.
1.6
Thus, complex III has the following structure:
1.4
1.2
1.0
0.8
0.6
0.4
0.2
HC
OH
HO S
N
2
3
O
Co
O
OH
2
OH
2
SO H
3
It is noteworthy that complex IV, unlike I, is dia-
magnetic; its square planar structure is confirmed by
DRS data (Table 4). During the thermal decomposition
of IV, the first endotherm is accompanied by a mass
loss corresponding to elimination of one coordinated
water molecule (Table 1) whose inner-sphere position
was confirmed by the IR spectrum (Table 3). The data
of the IR spectrum of IV, which exhibits bands for
azomethine, hydroxy group (aldehyde and acidic com-
ponents), and sulfo group vibrations (Table 3) attested
to a tridentate coordination of the ligand closing two
conjugated metal rings, a five- and a six-membered
ones. The following structure was proposed for IV:
0
2
4
6
8
Fig. 2. FTM of cobalt K-edge EXAFS for complex III,
experimental data (solid line) and the calculation results
(circles).l
the corresponding first derivative. A special feature of
the XANES first derivative for complex III is the pres-
ence of one major peak (~7708 eV), which is typical of
an octahedral geometry of the coordination unit and is
related to degeneracy of the vacant -orbitals of cobalt.
This is confirmed by the structural parameters found by
the non-linear fitting of the cobalt ä-edge EXAFS
function of complex III. Figure 2 shows the experimen-
tal and calculated FTM of cobalt K-edge EXAFS for
complex III, and Table 5 lists the structural character-
istics for the first coordination sphere of cobalt. Fitting
of the structural parameters was carried out using the
theoretical scattering phases and amplitudes calculated
for the nitriletriacetatotriaquacobalt(II) monohydrate,
C6H13CoNO9 · H2O [13] with a similar structure of the
coordination core.
OH
H
C
N
Ni
O
SO
3
H O
2
Thus, this study demonstrated that owing to the pro-
ton mobility, coordinated amino group readily under-
goes condensation, which is not accompanied by cleav-
age of the bonds in the coordination units of the initial
complexesA, B, and C. The nature of the aromatic alco-
hol affects the structure and composition of the result-
ing complexes. A specific behavior of benzoin is that
the ligand in I and II is the product formed upon double
condensation and bound to the metal in the tridentate
mode with closure of three conjugated rings (two six-
membered and one five-membered rings).
Table 5. Structural data for compound III obtained from
EXAFS data fitting
Composition
of the coordi-
nation sphere
N
R, Å
σ2, Å2
Q, %
O
2
1
3
2.02
2.09
2.12
0.0035
0.0041
0.0045
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