New binuclear metal chelate complexes of copper(II) chloride and acetate with bis(hetarylhydrazones) obtained by condensation of 2,6-diformyl-4-R-phenols with 2-hydrazinoquinoline

Article abstract of DOI:10.1007/s11173-005-0012-7

Bis(hetarylhydrazones) synthesized for the first time were used as ligands to obtain a number of binuclear copper(II) chelates from copper acetate and chloride. The physicochemical and, first of all, magnetic properties of the resulting complexes were studied. Analysis of the calculated exchange parameters showed that they differ significantly from those obtained previously for analogous binuclear metal chelates containing the identical set of donor atoms. Possible reasons for the differences in the magnetochemical behavior of the binuclear complexes obtained are discussed.

Full text of DOI:10.1007/s11173-005-0012-7

Russian Journal of Coordination Chemistry, Vol. 31, No. 2, 2005, pp. 146–149. Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 2, 2005, pp. 157–160.
Original Russian Text Copyright © 2005 by Lukov, Gevorkyan, Dontsova, Kogan, Popov, Dykov.
New Binuclear Metal Chelate Complexes of Copper(II) Chloride
and Acetate with Bis(hetarylhydrazones) Obtained
by Condensation of 2,6-Diformyl-4-R-Phenols
with 2-Hydrazinoquinoline
V. V. Lukov, I. E. Gevorkyan, E. V. Dontsova, V. A. Kogan, L. D. Popov, and V. V. Dykov
Rostov State University, ul. Zorge 7, Rostov-on-Don, 344104 Russia
Received February 19, 2004
Abstract—Bis(hetarylhydrazones) synthesized for the first time were used as ligands to obtain a number of
binuclear copper(II) chelates from copper acetate and chloride. The physicochemical and, first of all, magnetic
properties of the resulting complexes were studied. Analysis of the calculated exchange parameters showed that
they differ significantly from those obtained previously for analogous binuclear metal chelates containing the
identical set of donor atoms. Possible reasons for the differences in the magnetochemical behavior of the binu-
clear complexes obtained are discussed.
In continuation of the study of the complexing ability (II and III, respectively). The compositions and struc-
of bis(hetarylhydrazones) of 2,6-diformyl-4-R-phenols tures of the compounds obtained were confirmed by
[1–4], we synthesized a number of new ligands I and elemental analysis (Table 1), IR spectroscopy, magne-
their complexes with copper(II) acetate and chloride tochemistry, and conductometry.
R
N
O
N
N
N
R
Cu Cu
N
N
O
CH3
Cu(OAc)2
N
OH N
(II)
NH
NH
R
N
N
CuCl2
(I)
N
O
N
Cl
Cu Cu
N Cl
R = CH3, C(CH3)3, CH2Ph, C2H5
HN
NH
N
Cl
(III)
The IR spectra of complexes II contain no ν(OH) fragment of the quinoline residue, while the IR spectra
(phenol) or ν(N–H) absorption bands for the hydrazine of ligands I show the respective bands at 3350 and
1070-3284/05/3102-0146 © 2005 Pleiades Publishing, Inc.

NEW BINUCLEAR METAL CHELATE COMPLEXES
Table 1. Elemental analysis data for complexes II and III
147
Content (found/calculated), %
Type of the
complex
R
Empirical formula
ë
H
N
Cu
II
CH3
C28H22N6O2Cu2
C29H24N6O2Cu2
C30H28N6O2Cu2
C34H26N6O2Cu2
C27H21N6OCl3Cu2
C28H23N6OCl3Cu2
C29H27N6OCl3Cu2
C33H25N6OCl3Cu2
55.5/55.8
56.9/56.5
57.3/57.0
60.0/60.2
47.5/47.7
48.3/48.5
49.4/49.0
52.0/52.4
3.3/3.7
3.5/3.9
4.6/4.4
3.7/3.8
3.4/3.1
3.5/3.3
3.3/3.8
3.1/3.3
13.6/13.9
13.3/13.6
13.9/13.3
12.0/12.4
12.0/12.4
12.3/12.1
11.6/11.8
11.6/11.1
21.5/21.3
20.4/20.6
20.3/20.1
18.5/18.7
18.6/18.8
18.0/18.3
18.4/18.0
18.9/18.6
II
C2H5
II
C(CH3)3
CH2Ph
CH3
II
III
III
III
III
C2H5
C(CH3)3
CH2Ph
3190 cm–1 [5]. The ν(N–H) absorption band is retained
in the IR spectra of complexes III.
O
O
Cu
Cu less planar, with the respective reduction of
The molar conductivities λ of complexes III in
the contribution from the antiferromagnetic constituent
DMF (Table 2) suggest their insignificant dissociation to the resultant exchange interaction [8, 9]. Obviously,
with release of one Cl atom [6]. Apparently, in binu- replacement of one of the bridging O atoms by a Cl
clear complexes III based on 2-hydrazinoquinoline, in atom and, as noted above, axial coordination of the two
contrast to analogous systems containing 2-hydrazi- other Cl atoms will further distort the exchanged frag-
ment with the corresponding weakening of antiferro-
magnetism, which is really observed (Table 3).
nobenzoimidazole [3, 4], both Cl atoms are axially
coordinated by copper atoms. The latter circumstance
seems to account for some differences in magne-
tochemical behavior between these complexes and
those of copper(II) chloride with ligands I, which were
described in [2, 4].
The totality of our experimental data allows one to
state that for the complexes under discussion (obtained
from both copper(II) acetate and copper(II) chloride),
the geometrical factors determining the structural fea-
tures of the exchanged fragments have a decisive effect
on the character and strength of exchange interactions
since there is no noticeable correlation between 2J val-
ues and the electronic nature of a substituent in the phe-
nol fragment of ligands I. Previously, a satisfactory cor-
relation of this type was obtained only for copper(II)
complexes with bis(acylhydrazone) derivatives of 2,6-
diformyl-4-R-phenols [10, 11].
According to the temperature dependence of the
magnetic susceptibility of complexes III, complexes
with R = CH3 and C2H5 are trivial paramagnetics, while
complexes with R = CH2Ph and C(CH3)3 are character-
ized by antiferromagnetic exchange interactions (2J =
−61.6 and –145.2 cm–1, respectively) (Table 3). The
antiferromagnetism of complexes II is more pro-
nounced than that of complexes III (Table 3); this is not
surprising because the structural distortion in the
O
EXPERIMENTAL
exchanged fragment Cu
Cu is smaller than in
O
Ligands I were synthesized by refluxing a corre-
sponding 2,6-diformyl-4-R-phenol (0.001 mol) with
2-hydrazinoquinoline (0.002 mol) in 10 ml of ethanol
O
Cu
Cu [7].
Cl
However, it should be noted that the exchange
parameters 2J of binuclear metal chelates II (Table 3)
are, on average, half the absolute values obtained ear-
lier for binuclear copper(II) acetate complexes with 2-
hydrazinobenzoimidazole [1]. Apparently, their
reduced antiferromagnetism is mainly due to more con-
siderable steric hindrances in structure II than in ben-
zoimidazole derivatives because of repulsion of the
fused aromatic rings of the quinoline fragment. The lat-
ter circumstance should make the exchanged fragment
Table 2. Molar conductivities of complexes III in DMF
R
λ, cm2 Ω–1 mol–1
CH3
4.7
10.8
12.0
12.7
C2H5
C(CH3)3
CH2Ph
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 31 No. 2 2005

148
LUKOV et al.
Table 3. Magnetic properties of binuclear copper complexes II and III
Complex II: R = CH3, 2J = –334 cm–1, g = 2.13, f* = 0.07, r = 1.25%
T, K
292
251
225
158
110
83
exp
eff
1.34
1.22
1.16
0.95
0.79
0.70
**
µ
, µB
calc
eff
1.34
1.24
1.16
0.88
0.63
0.53
µ
, µB
Complex II: R = C2H5, 2J = –330 cm–1, g = 2.16, f = 0.07, r = 0.5%
T, K
297
275
252
250
240
215
178
157
138
118
102
86
exp
eff
1.37
1.33
1.27
1.26
1.23
1.15
1.00
0.90
0.79
0.69
0.61
0.55
µ
, µB
, µB
calc
eff
1.37
1.33
1.27
1.26
1.23
1.15
1.00
0.90
0.80
0.68
0.60
0.54
µ
Complex II: R = C(CH3)3, 2J = –309.2 cm–1, g = 2.04, f = 0.06, r = 0.46%
T, K
298
273
250
240
215
180
161
135
120
102
86
exp
eff
1.33
1.28
1.22
1.20
1.12
0.99
0.90
0.77
0.67
0.67
0.58
0.50
0.50
µ
, µB
, µB
calc
eff
1.33
1.28
1.23
1.20
1.12
0.99
0.90
0.77
0.58
µ
Complex II: R = CH2Ph, 2J = –278.8 cm–1, g = 2.20, f = 0.1, r = 0.45%
T, K
293
274
251
235
207
192
166
145
126
110
88
82
exp
eff
1.50
1.47
1.42
1.38
1.30
1.24
1.14
1.03
0.92
0.83
0.71
0.68
µ
, µB
, µB
calc
eff
1.50
1.47
1.42
1.38
1.30
1.24
1.14
1.03
0.92
0.83
0.71
0.68
µ
Complex III: R = CH3
T, K
290
1.79
243
185
126
99
83
1.78
exp
1.77
1.79
1.73
1.73
µ
, µB
eff
Complex III: R = C2H5
T, K
294
274
1.81
263
1.80
227
195
179
148
123
1.77
103
91
82
exp
1.81
1.79
1.79
1.78
1.77
1.77
1.77
1.76
µ
, µB
eff
Complex III: R = C(CH3)3, 2J = –145.2 cm–1, g = 2.20, r = 0.38%
T, K
294
263
246
205
188
173
150
123
110
94
82
exp
eff
1.70
1.67
1.65
1.59
1.55
1.51
1.44
1.31
1.23
1.10
0.97
µ
, µB
, µB
calc
eff
1.70
1.67
1.65
1.59
1.55
1.51
1.44
1.31
1.23
1.10
0.97
µ
Complex III: R = CH2Ph, 2J = –61,6 cm–1, g = 2.12, r = 0.27%
T, K
295
272
254
231
209
180
150
125
99
91
82
exp
eff
1.76
1.76
1.75
1.74
1.73
1.71
1.67
1.64
1.58
1.55
1.51
µ
, µB
, µB
calc
eff
1.76
1.75
1.75
1.74
1.73
1.71
1.68
1.64
1.58
1.55
1.51
µ
* f is the fraction of the paramagnetic admixture in the binuclear sample.
**All the µ values were calculated per copper atom in the binuclear molecule.
eff
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 31 No. 2 2005

NEW BINUCLEAR METAL CHELATE COMPLEXES
149
where χi and χ0i are the experimental and theoretical
molar magnetic susceptibilities at the ith point, respec-
tively; n is the number of points.
for 3 h. The resulting precipitate was filtered off,
washed with hot ethanol, and dried in air.
Complexes II and III were synthesized as follows.
A suspension of ligand I (0.001 mol) in methanol was
mixed with a hot solution of copper(II) chloride or ace-
tate (0.002 mol) in methanol. The mixture was refluxed
for 6 h and then cooled. The resulting precipitate was
filtered off, washed with hot methanol, and dried in air.
Elemental analysis data for all compounds obtained are
given in Table 1.
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--
n




r =
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--
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

∑
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1
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