Binuclear Cu(II) and Ni(II) Complexes with Schiff Bases - The Products of Condensation of Amino Alcohols with 2-Phenylhydrazone 1-Phenylbutane-1,2,3- Trione: Synthesis and Magnetic Properties

Article abstract of DOI:10.1023/A:1025611727728

The binuclear complexes of Cu²⁺ and Ni²⁺ with a new ligand system obtained through condensation of amino alcohols with 2-phenylhydrazone 1-phenylbutane-1,2,3-trione were synthesized. The compositions and structures of ligands and complexes were determined using elemental analysis, IR and NMR spectroscopy and magnetochemistry. The nickel complexes were found to be diamagnetic; in the copper complexes, substantial antiferromagnetic exchange interaction was observed (for Cu²⁺ complexes with n = 2 and 3, 2J is equal to -396 and -393 cm^-1, respectively). The structure of the exchange fragment (Equation Presented) is discussed.

Full text of DOI:10.1023/A:1025611727728

Russian Journal of Coordination Chemistry, Vol. 29, No. 9, 2003, pp. 639–642. Translated from Koordinatsionnaya Khimiya, Vol. 29, No. 9, 2003, pp. 689–692.
Original Russian Text Copyright © 2003 by Dontsova, Lukov, Kogan, Popov.
Binuclear Cu(II) and Ni(II) Complexes with Schiff
Bases—the Products of Condensation of Amino Alcohols
with 2-Phenylhydrazone 1-Phenylbutane-1,2,3-Trione:
Synthesis and Magnetic Properties
E. V. Dontsova, V. V. Lukov, V. A. Kogan, and L. D. Popov
Rostov State University, pr. Stachki 194/3, Rostov-on-Don, 344104 Russia
Received September 3, 2002
Abstract—The binuclear complexes of Cu2+ and Ni2+ with a new ligand system obtained through condensation
of amino alcohols with 2-phenylhydrazone 1-phenylbutane-1,2,3-trione were synthesized. The compositions
and structures of ligands and complexes were determined using elemental analysis, IR and NMR spectroscopy
and magnetochemistry. The nickel complexes were found to be diamagnetic; in the copper complexes, substantial
antiferromagnetic exchange interaction was observed (for Cu2+ complexes with n = 2 and 3, 2J is equal to –396
O
and –393 cm–1, respectively). The structure of the exchange fragment
is discussed.
Cu
Cu
O
The β-diketones are known to enter rather easily the plexes with similar ligands through introduction of
azo coupling reaction with aryldiazonium salts to yield additional chelatophore groups in arylhydrazones (I),
hydrazones, which are potential N,N,N- and N,N,O- which are the products of azo coupling of aryldiazo-
donor ligands [1–3]. However, all compounds contain- nium salts with β-dicarbonyl compounds. We intended
ing these ligands are merely mononuclear metal che- to synthesize these complexes by the following reac-
lates. It was of interest to synthesize polynuclear com- tions:
CH3
CH2
CH3
O + Cl–[N2]+–Ph
O
–HCl
Ph
Ph
(1)
(2)
O
O
N NH
(I)
Ph
NH
Ar
O
H3C
CH3
O
N
O
Ph
Ph
+
NH2 NH C Ar
O
N NH
O
N NH
Ph
Ph
However, as follows from further investigations, no basic nitrogen atom of aromatic or aliphatic amines pro-
condensation occurs between the carbonyl oxygen atom ceeds almost quantitatively. On the other hand, conden-
of hydrazones I and aromatic hydrazides by reaction (2). sation between hydrazones I and amino alcohols (etha-
This was rather surprising, since in the above-cited nol- and propanolamine) proceeds smoothly, which
works, the condensation of the carbonyl group with less made it possible to synthesize ligand systems (II):
H3C
CH3
(CH2)n OH
N
O
Ph
Ph
+ H2N–(CH2)n–OH
(3)
O
N NH
O
N NH
Ph
Ph
(II, H2L) n = 2, 3
1070-3284/03/2909-0639$25.00 © 2003 åÄIä “Nauka /Interperiodica”

640
DONTSOVA et al.
Table 1. Results of elemental analysis of ligands II and complexes III and IV
Composition (found/calcd), %
Compound
n*
Empirical formula
C
H
N
M
II
2
3
2
3
2
3
C18H19N3O2
70.1/69.9
70.4/70.6
57.8/58.1
58.8/59.0
58.6/58.9
60.1/60.4
5.9/6.1
6.6/6.5
4.6/4.8
5.4/5.2
4.9/5.1
5.2/5.0
13.9/13.6
12.8/13.0
11.1/11.3
10.7/10.9
11.6/11.4
10.9/11.1
II
C19H21N3O2
III
III
IV
IV
C36H36N6O4Cu2
C38H40N6O4Cu2
C36H36N6O4Ni2
C38H40N6O4Ni2
17.4/17.2
16.8/16.6
16.5/16.1
15.6/15.4
* n is the number of (CH ) groups.
2
The formulas of these ligands evidence that they can be binuclear complexes of transition metals in the first period
considered as tridentate dibasic systems similar to those that of the Periodic Table. We obtained a series of new Cu2+ and
were described in [4–6] and were used to synthesize the Ni2+ complexes (III, IV) with ligands II.
Ph
(CH2)n
H3C
H3C
(CH2)n OH
N
N N
N
O
N
Ph
O
Cu
Ph
Cu
+ Cu(OAc)2
+ Ni(OAc)2
(4)
(5)
O
Ph
O
N N
O
N NH
CH3
(CH2)n
Ph
Ph
(III), n = 2, 3
Ph
(CH2)n
H3C
H3C
(CH2)n OH
N
N N
N
O
N
Ph
O
Ni
Ph
Ni
O
Ph
O
N N
O
N NH
CH3
(CH2)n
Ph
Ph
(IV), n = 2, 3
The composition and structure of all ligands and respectively, disappeared from the spectra. The effec-
tive magnetic moments of copper chelates (per one cop-
per atom) even at room temperature were noticeably
smaller than a purely spin value (1.73 µB, Table 2).
When the temperature was lowered to liquid nitrogen
complexes were determined using elemental analysis,
IR and NMR spectroscopy and magnetochemistry. The
NMR spectra of ligands II (n = 2, 3) exhibited signals
with integrated intensities corresponding to the total
number of their protons: a singlet at 2.5 ppm (3H) from temperature, the effective magnetic moment (µeff) fur-
the methyl group protons, singlet signals at 3.6 (2H) and
3.8 ppm (3H) from two (n = 2) or three (n = 3) methylene
group protons, respectively, a singlet at 5 ppm (1H) from
the NH proton of the hydrazine group, a multiplet signal
at 7–8 ppm from the protons of two benzene rings, and a
singlet at 15 ppm (1H) from the hydroxyl proton.
ther lowered, thus suggesting a strong antiferromag-
netic exchange interaction between two copper atoms
in dimeric complex III. The magnetic properties of
complex III were explained in terms of the isotropic
Heiselberg–Dirac–van Vleck model using a modified
Bleaney–Bowers equation, which accounts for a small
amount of paramagnetic impurities in the dimeric sample
[9]. The calculated exchange parameters (2J) (Table 2)
are in good agreement with the exchange parameters of
the binuclear copper(II) complexes with polydentate
ligands based on the products of condensation of ami-
noethanol and aminopropanol with substituted salicyl-
aldehyde derivatives [6]. Rather large (in absolute
Reactions of ligands II with copper(II) or nickel(II)
acetates (reactions (4) and (5), respectively) resulted in
ML complexes, where L2– is a doubly deprotonated
form of the ligand (Table 1). Coordination was con-
firmed by the fact that the alcohol OH and hydrazine
NH stretching vibration bands, which were observed in
the spectra of free ligands at 3400 and 3200 cm–1, value) parameters of antiferromagnetic exchange inter-
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 29 No. 9 2003

BINUCLEAR Cu(II) AND Ni(II) COMPLEXES
Table 2. Magnetic properties of binuclear complexes III
641
T, K
289
258
238
218
197
163
142
121
100
82
n = 2, 2J = –396 cm–1, g = 2.00, f* = 0.11, r** = 1.74%
exp***
µeff
1.20
1.18
1.10
1.10
1.04
1.05
0.98
0.99
0.92
0.92
0.80
0.79
0.71
0.72
0.65
0.65
0.61
0.61
0.58
0.58
, µB
µceafflcd , µB
n = 3, 2J = –392 cm–1, g = 2.02, f = 0.08, r = 1.98%
exp
eff
1.17
1.17
1.10
1.11
1.04
1.05
0.98
0.99
0.82
0.83
0.75
0.75
0.67
0.66
0.60
0.59
0.54
0.53
0.50
0.51
µ
µ
, µB
calcd
eff
, µB
* f is a fraction of paramagnetic impurities.
** r is the root-mean-square error.
exp
eff
*** The µ
values were determined by the relative Faraday method (the µ values were calculated per one copper atom in binuclear
eff
calcd
eff
molecule); µ
were calculated within the framework of a modified Bleany–Bower equation using the determined exchanged
parameter 2J.
action apparently indicate that the structure of the (0.001 mol) in 15 ml methanol (or of nickel(II) acetate
O
α
O
in 5 ml methanol) was added to a solution of ligand
(0.001 mol) in 10 ml methanol and boiled for 10 min
with stirring. The precipitate that was formed after
cooling was filtered off and washed with hot methanol.
The results of elemental analysis of these complexes
are given in Table 1.
IR spectra were recorded on an UR-20 instrument
in the 700–4000 cm–1 range; the samples were prepared
in the form of suspensions in mineral oil.
1H NMR spectra were taken on a UNITY-300 spec-
trometer with DMSO-d6 as a solvent and tetramethylsi-
lane as a standard.
Magnetic susceptibility was determined by the rel-
ative Faraday method over the temperature range of 78–
300 K using a setup designed at the Chair of Physical
and Colloidal Chemistry, Rostov State University.
Hg[Co(CNS)4] was used as a standard for calibration.
The exchange parameters were calculated from the
temperature dependence of magnetic susceptibility
within the framework of the dimeric Heiselberg–Dirac–
van Vleck model using a modified Bleaney–Bowers
equation [9]; also, the program minimizing root-mean-
square error was used.
Cu
Cu
is close to planar and the
exchange fragment
bond angle α ≥ 100° [8]. Unfortunately, we had no pos-
sibility to carry out X-ray diffraction analysis of metal
chelates obtained, because their single crystals were not
available.
Ligands II react with nickel(II) acetate to give coor-
dination compounds NiL (Table 1). The IR spectra of
these complexes are similar to those of metal chelates
III. They are diamagnetic, which points to a planar
structure of their coordination cores and agrees well
with diamagnetism of nickel chelates containing the
ligands obtained through condensation of amino alco-
hols with N-tolylsubstituted derivatives of salicylalde-
hyde [5]. These data confirm that the nickel(II) com-
plexes synthesized have binuclear structure IV.
Thus, this study evidenced that the Schiff bases syn-
thesized in this work through the condensation of
monoethanol- and monopropanolamine with 2-phenyl-
hydrazon 1-phenylbutane-1,2,3-trione act as tridentate
dibasic ligands and form with Cu2+ and Ni2+ ions binu-
clear complexes with a planar coordination core N2O2.
EXPERIMENTAL
ACKNOWLEDGMENTS
2-Phenylhydrazone 1-phenylbutane-1,2,3-trione
(I) was synthesized using the known procedure [10].
This work was supported by the Russian Foundation
for Basic Research, project no. 01-03-32724.
Ligands II were obtained by boiling equimolar
mixture of hydrazone I and amino alcohol in methanol
for 2 h. The precipitate formed after cooling was further
filtered off, recrystallized from a heptane–ethylacetate
(2 : 1) mixture, and dried in air. The results of elemental
analysis are presented in Table 1.
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RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 29 No. 9 2003

642
DONTSOVA et al.
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