Coordination compounds of cobalt, nickel, and copper with isonitrosoacetone benzoylhydrazone

Article abstract of DOI:10.1023/A:1015490022087

Benzoylhydrazine and isonitrosoacetone react in ethanol with cobalt, nickel, and copper halides and acetates to give the coordination compounds MX₂(HL)·nH₂O, MX₂(HL) ₂·nH₂O, and ML₂·nH₂O [M = Co, Ni, Cu; X = Cl, Br; HL = C₆H₅C(O)NHNC(CH ₃)CHNOH; n = 1-4]. The same reactions performed in the presence of sodium acetate and pyridine (pH 7-8) yield the complexes MLCl·nH ₂O and MPy₂LCl·nH₂O (n = 1-4). All the complexes have a pseudooctahedral coordination geometry. The hydrazone HL behaves as a tridentate O,N,N-donor ligand. Thermolysis of the substances involves dehydration (70-90°C), deaquation (155-170°C) or deamination (175-195°C), and complete thermal decomposition (285-360°C).

Full text of DOI:10.1023/A:1015490022087

Russian Journal of General Chemistry, Vol. 72, No. 2, 2002, pp. 276 279. Translated from Zhurnal Obshchei Khimii, Vol. 72, No. 2, 2002,
pp. 299 303.
Original Russian Text Copyright
2002 by Tsapkov.
Coordination Compounds of Cobalt, Nickel, and Copper
with Isonitrosoacetone Benzoylhydrazone
V. I. Tsapkov
Moldova State University, Chisinau, Moldova
Received March 6, 2000
Abstract Benzoylhydrazine and isonitrosoacetone react in ethanol with cobalt, nickel, and copper halides and
acetates to give the coordination compounds MX2(HL) nH2O, MX2(HL)2 nH2O, and ML2 nH2O [M = Co,
Ni, Cu; X = Cl, Br; HL = C6H5C(O)NHNC(CH3)CHNOH; n = 1 4]. The same reactions performed in the
presence of sodium acetate and pyridine (pH 7 8) yield the complexes MLCl nH2O and MPy2LCl nH2O
(n = 1 4). All the complexes have a pseudooctahedral coordination geometry. The hydrazone HL behaves
as a tridentate O,N,N-donor ligand. Thermolysis of the substances involves dehydration (70 90 C), deaquation
(155 170 C) or deamination (175 195 C), and complete thermal decomposition (285 360 C).
Benzoylhydrazones of aliphatic and aromatic alde-
hydes or ketones contain a set of different donor
atoms and form with transition metal ions various
coordination compounds differing in the composition,
structure, and properties [1 4]. Many of these sub-
stances exhibit biological activity [5, 6], which makes
them promising as biochemical agents and pharma-
ceuticals. In this connection, synthesis and study of
new coordination compounds of biometals with ben-
zoylhydrazones is of both scientific and practical
interest.
XIII) are formed, where M2+ = Co (VIII, XI), Ni (IX,
XII), Cu (X, XIII); n = 0 (XIII), 1 (XI, XII), 3 (X),
4 (VIII, IX).
Cobalt and nickel acetates react in ethanol with
benzoylhydrazine and isonitrosoacetone (molar ratio
1 : 2 : 2) to form coordination compounds XIV and
XV of the composition ML2 nH2O (XIV, XV), where
M2+ = Co (XIV), Ni (XV); n = 2 (XV), 3 (XIV).
Compounds I XV are insoluble in ether, sparingly
soluble in water and alcohols, and readily soluble in
dimethylformamide and dimethyl sulfoxide. Their
yields and physicochemical characteristics are listed
in Table 1.
The goal of this work was to find optimal synthe-
sis conditions, determine the composition and proba-
ble structure, and study physicochemical properties of
cobalt, nickel, and copper complexes with isonitroso-
acetone benzoylhydrazone HL.
The analytical data for I XV (Table 1) suggest
that, similar to the reactions described in [7 9], tem-
plate condensation of benzoylhydrazine with isonitro-
soacetone occurs on the Co2+, Ni2+, or Cu2+ matrix
with formation of the Schiff base HL forming with the
metal ions coordination compounds I XV.
C NH N=C CH3
O HO N=C H
HL
Determination of the molar electrolytic conductiv-
ity of the complexes in DMF showed that compounds
I V and VIII XV are nonelectrolytes, whereas com-
pounds VI and VII are 1 2 electrolytes [ (VI) 149,
Experiment showed that reactions of ethanolic
solutions of benzoylhydrazine and isonitrosoacetone
with Co, Ni, and Cu chlorides or bromides (molar
ratio 1 : 1 : 1 and 2 : 2 : 1) yield finely crystalline sub-
stances identified by elemental analysis (Table 1) as
MX2(HL) nH2O (I V) and MCl2(HL)2 nH2O (VI,
1
3
(VII) 160
1 cm2 mol , 20 C, 10 M].
Magnetochemical study showed (Table 1) that the
cobalt ion in I, II, VI, VII, XI, and XIV occurs in the
oxidation state 2+ (electronic state t52g eg2). The nickel
compounds III, VII, IX, XI, and XV are paramag-
netic and, as judged from the effective magnetic mo-
ments, have the pseudooctahedral structure of the co-
ordination core (electronic state of the central atom
t62g eg2). All the copper complexes are monomeric, as
VII), where M2+ = Co (I, II, VI), Ni (III, VII), Cu
(IV, V); X = Cl (I, III, IV), Br (II, V); n = 1 (VII),
2 (II, VI), 3 (I, III, V), 4 (IV).
When the reaction is performed in the presence of
sodium acetate or pyridine (pH 7 8), the complexes
MLCl nH2O (VIII X) and MPy2LCl nH2O (XI
1070-3632/02/7202-0276$27.00 2002 MAIK Nauka/Interperiodica

COORDINATION COMPOUNDS OF COBALT, NICKEL, AND COPPER
277
Table 1. Physicochemical characteristics of cobalt, nickel, and copper coordination compounds with isonitrosoacetone
benzoylhydrazone
Found, %
M
Calculated, %
M
Comp. Yield,
eff, BM
(294 K)
Formula
no.
%
Cl (Br)
N
Cl (Br)
N
I
II
III
IV
V
VI
VII
VIII
IX
X
XI
XII
XIII
XIV
XV
78
86
81
72
83
69
65
79
76
75
86
82
83
78
79
4.89
5.02
2.87
1.79
1.76
5.01
2.91
5.11
2.94
1.78
4.93
3.09
1.87
4.94
2.99
18.01
(34.47)
18.14
16.94
(32.87)
12.09
12.48
9.29
9.37
9.64
7.24
7.30
14.96
12.64
15.25
15.41
12.96
11.96
10.30
15.69
15.74
17.71
12.26
12.20
13.81
11.09
11.49
10.57
8.90
10.61
9.88
C10H17Cl2CoN3O5
C10H15Br2CoN3O4
C10H17Cl2N3NiO5
C10H19Cl2CuN3O6
C10H17Br2CuN3O5
C20H26Cl2CoN6O6
C20H24Cl2N6NiO5
C10H18ClCoN3O6
C10H18ClN3NiO6
C10H16ClCuN3O5
C20H22ClCoN5O3
C20H22ClN5NiO3
C20H20ClCuN5O2
C20H26CoN6O7
18.25
(34.78)
18.25
17.23
(33.13)
12.33
12.72
9.58
9.58
9.93
7.48
7.48
15.17
12.83
15.17
15.53
13.25
10.24
10.57
15.92
15.92
17.90
12.43
12.43
13.87
11.32
11.73
10.80
9.13
10.80
10.19
8.70
14.58
15.05
11.34
11.34
11.75
14.75
14.75
15.17
16.12
16.70
8.54
14.31
14.76
11.06
11.20
11.62
14.60
14.53
14.86
15.87
16.53
7.45
7.69
C20H24N6NiO6
Table 2. Results of thermal analysis of Co, Ni, and Cu coordination compounds with isonitrosoacetone benzoylhydrazone
Number of
Comp. endoeffect
Weight loss
Kinetic parameters
of the processes
Temperature
of complete
decomposition,
C
T,
C
no.
in the DTA
curve
found,
%
calculated,
%
corresponds
to loss of
1
Ea, kJ mol
log Z
I
1
2
1
2
1
2
1
2
1
2
1
1
1
2
1
2
1
2
1
2
1
2
1
1
1
75
175
80
165
70
170
75
160
70
150
90
85
85
180
70
160
75
145
65
195
80
180
165
70
9.0
4.5
4.0
4.3
9.5
4.3
13.0
4.5
7.5
4.0
6.5
3.0
9.5
9.5
10.0
9.5
5.2
9.6
4.0
9.2
4.6
3.9
3.9
9.2
4.6
13.2
4.4
7.4
3.7
6.3
3.2
9.7
9.7
9.7
9.7
5.0
10.0
3.8
2H2O
H2O
H2O
H2O
2H2O
H2O
3H2O
H2O
2H2O
H2O
2H2O
H2O
2H2O
2H2O
2H2O
2H2O
H2O
2H2O
H2O
2C5H5N
H2O
2C5H5N
2C5H5N
3H2O
2H2O
38.9
56.4
33.2
52.1
36.6
54.9
31.6
49.9
34.1
47.8
39.2
34.5
41.1
75.2
42.9
74.1
35.8
65.6
40.1
96.3
35.3
95.0
82.4
38.7
40.4
7.8
9.6
7.3
8.9
7.6
9.2
6.8
8.7
7.1
8.7
8.6
7.5
8.2
10.4
8.6
10.3
7.5
9.6
8.8
12.0
7.5
11.8
11.2
8.5
8.7
390
370
390
355
340
II
III
IV
V
VI
VII
VIII
435
430
420
IX
X
410
375
450
445
XI
XII
33.0
3.5
33.1
35.5
10.5
7.0
33.3
3.1
33.3
34.2
10.4
7.2
XIII
XIV
XV
410
485
480
80
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 72 No. 2 2002

278
TSAPKOV
their effective magnetic moments at room temperature
correspond to the spin value for one unpaired electron.
The third endothermic effect in the DTA curves at
340 485 C corresponds to thermal oxidative degra-
dation of the coordinated hydrazone L. The tempera-
ture of the maximum of this effect depends on the
central atom and for compounds of similar composi-
tion decreases in the order Co > Ni > Cu. The temper-
ature of complete decomposition is also influenced by
the inner-sphere ligands: it increases on deprotonation
of hydrazone L and replacement of Br by Cl . Using
the Horowitz Metzger method [13] supplemented by
Topor [14], we estimated the kinetic parameters of
dehydration, deaquation, and deamination of I XV.
The results are listed in Table 2. It is seen that the
evaluated activation energies Ea and preexponential
terms Z are close to those reported in the literature for
similar topochemical processes [15 17]. Experiment
showed (Table 2) that the kinetic parameters of elimi-
nation of inner-sphere water and pyridine molecules
are affected by the nature of the central atom and
acido ligand; for the compounds of similar composi-
tion, these parameters decrease in the order Co > Ni >
Cu and Cl > Br. The nature of the leaving group also
affects the kinetic parameters: In going from aqua to
pyridine complexes Ea and log Z increase, which is
consistent with the increase in both -donor and -ac-
ceptor power of the ligand.
To determine the mode of the ligand coordination
with the central ions, we compared the IR spectra of
the initial substances and complexes I XV. The spec-
tra of the complexes contain no bands belonging to
(C=O) of isonitrosoacetone and (NH) of the amino
group in benzoylhydrazine, which proves formation of
hydrazone HL. In I XV it acts as a tridentate ligand
coordinating with the central atom via amide oxygen,
hydrazine nitrogen, and oxime nitrogen to form two
five-membered chelate rings. This assumption is sup-
ported by the fact that in the IR spectra of the com-
1
plexes the bands (C=O) at 1650 1640 cm and
1
(C=N) at 1605 1595 cm 1 are shifted by 25 30 cm
toward lower frequencies as compared to the corre-
sponding bands in the spectra of benzoylhydrazine,
isonitrosoacetone, and related Schiff bases described
in the literature [10 12]. Furthermore, it should be
noted that in VIII XV hydrazone occurs in the depro-
tonated (L) imidoalcoholic tautomeric form. This is
indicated by the disappearance of the (C=O) band at
1
1650 1640 cm from the IR spectra of these com-
pounds, splitting of the (C O) band in two (1295
1
1285 and 1280 1275 cm ), and also appearance of
1
the (>C=N N=C<) band at 1585 1575 cm . Partici-
pation of the other functional groups of L in coordina-
tion with the metal ions can be ruled out, because
their characteristic absorption bands are observed in
the same regions as in the spectra of the initial benzo-
ylhydrazine and isonitrosoacetone. The presence in
VIII XIII of coordinated water and pyridine mole-
cules is confirmed by the presence in their IR spectra
of the corresponding absorption bands: in the case of
aqua complexes VIII X, (H2O) 3590 3580, (H2O)
The physicochemical data obtained suggest for
I XV structures A (I V), B (VI, VII), C (VIII XIII),
and D (XIV, XV).
1
1595 1590, and (H2O) 925 920 cm ; in the case of
pyridine complexes XI XIII, (CC) + (CN) +
(CCH) 1640 1635, 1530 1525, (CN) 1310 1305,
(CCH) 1230 1225, (CCH) + (CC) + (CNC)
1060 1055, 1030 1025, (CCC) + (CNC) 730 725,
1
(CH) 830 825 cm .
Then, it was interesting to study the thermal behav-
ior of I XV and to examine the effect of the central
atom and ligand surrounding on the temperature of
possible phase transitions, and also to study the kinet-
ics of these processes. Experiment showed (Table 2)
that thermolysis of I XV involves a sequence of
stages. The endothermic effect observed in the DTA
curves at 70 90 C, i.e., at a relatively low tempera-
ture, apparently corresponds to dehydration. The
second endothermic effect is observed at higher tem-
peratures: 145 175 C for I V and VIII X and 165
195 C for XI XIII. As judged from the weight loss,
this effect corresponds to deaquation or deamination.
M = Co, Ni, Cu; X = Cl, Br; Y = H2O, C5H5N; n = 0 3.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 72 No. 2 2002

COORDINATION COMPOUNDS OF COBALT, NICKEL, AND COPPER
279
EXPERIMENTAL
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(mulls in mineral oil) after drying in an oven at 105 C
to constant weight. The effective magnetic moments
of I XV were determined by the Gouy method. The
molar magnetic susceptibility, corrected for diamag-
netism, was calculated using theoretical susceptibili-
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was performed with a Paulik Paulik Erdey derivato-
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balt(II) chloride hexahydrate. The mixture was con-
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Compounds II VII, XIV, and XV were prepared
similarly starting from benzoylhydrazine, isonitroso-
acetone, and hydrate of Co, Ni, or Cu chloride, bro-
mide, or acetate in the molar ratio of 1 : 1 : 1 or
2 : 2 : 1. Complexes VIII XIII were prepared by the
reaction of the above-mentioned compounds (molar
ratio 1 : 1 : 1) in the presence of sodium acetate or
pyridine (pH 8). The yields and some physicochem-
ical characteristics of the substances are listed in
Tables 1 and 2.
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1963, vol. 35, no. 10, pp. 1398 1403.
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RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 72 No. 2 2002