Metal complexes and solvent extraction properties of isonitrosoacetophenone 2-aminobenzoylhydrazone

Article abstract of DOI:10.1016/j.saa.2006.01.004

Three types of copper complexes as well as an oximate-bridged nickel complex with isonitrosoacetophenone 2-aminobenzoylhydrazone (H₂L) have been prepared in ethanolic solution and characterized by elemental analyses, IR, ¹H NMR, UV-vis and magnetic susceptibility measurement. IR spectra show the ligand coordinates as a neutral, monoanionic and dianionic O,N,N-tridentate acylhydrazoneoxime ligand depending reaction conditions and metal salts employed. The elemental analyses results, spectroscopic and magnetic data are consistent with the formation of mononuclear copper complexes and binuclear complexes with both copper and nickel. The effects of varying pH and solvent on the absorption behavior of both ligand and complexes have been investigated. The extraction ability of acylhydrazoneoxime ligand has been examined by the liquid-liquid extraction of selected transition metal [Cu²⁺, Ni²⁺, Co²⁺, Cr³⁺, Hg²⁺, Zn²⁺, Cd²⁺ and Mn²⁺] cations. The ligand shows strong binding ability toward copper(II) ion.

Full text of DOI:10.1016/j.saa.2006.01.004

Spectrochimica Acta Part A 65 (2006) 719–726
Metal complexes and solvent extraction properties of
isonitrosoacetophenone 2-aminobenzoylhydrazone
Ramazan Gupa,∗, Emrah Giziroglu
b
˘
a Department of Chemistry, Mugla University, Kotekli, 48000 Mugla, Turkey
b Department of Chemistry, Adnan Menderes University, Kampus, Aydın, Turkey
Received 16 November 2005; received in revised form 5 January 2006; accepted 8 January 2006
Abstract
Three types of copper complexes as well as an oximate-bridged nickel complex with isonitrosoacetophenone 2-aminobenzoylhydrazone (H2L)
have been prepared in ethanolic solution and characterized by elemental analyses, IR, 1H NMR, UV–vis and magnetic susceptibility measurement.
IR spectra show the ligand coordinates as a neutral, monoanionic and dianionic O,N,N-tridentate acylhydrazoneoxime ligand depending reaction
conditions and metal salts employed. The elemental analyses results, spectroscopic and magnetic data are consistent with the formation of
mononuclear copper complexes and binuclear complexes with both copper and nickel. The effects of varying pH and solvent on the absorption
behavior of both ligand and complexes have been investigated. The extraction ability of acylhydrazoneoxime ligand has been examined by the
liquid–liquid extraction of selected transition metal [Cu2+, Ni2+, Co2+, Cr3+, Hg2+, Zn2+, Cd2+ and Mn2+] cations. The ligand shows strong binding
ability toward copper(II) ion.
© 2006 Elsevier B.V. All rights reserved.
Keywords: Hydrazoneoxime ligands; Transition metal cations; Complexes; IR and electronic spectra; Solvent extraction
1. Introduction
expanded the use of solvent extraction for metal recovery and
purification. Oximes have been widely used as extractants for
metal ions in solvent extraction.
In this paper, we report the synthesis and spectroscopic inves-
tigation of mono- and dinuclear complexes of hydrazoneoxime
ligand, isonitrosoacetophenoneanthranoylhydrazone(H2L). We
also investigate the possible utilization of this compound in
metal extractions from aqueous solutions into organic solvents.
Oximes and hydrazones are the two important classes of com-
pounds owing to their wide applications in industry, medicine,
detection and determination of various metal ions [1–9]. These
compounds have a number of potential bonding sites such as
carbonyl oxygen, azomethine and imine nitrogens. Therefore,
hydrazone and oximes as well as their coordination compounds
have been studied extensively [10–15].
2. Experimental
Hydrazoneoximes can react with copper(II) and nickel(II)
salts to produce either mono- or binuclear complexes. The keto
hydrazone moiety may coordinate to metals in the ketoamide or
deprotonated enolimine form. Such compounds containing both
oxime and hydrazone groups typically act as tridentate, mono-
or biprotic ligands coordinating through the amide oxygen,
imine and oxime nitrogens depending on the reaction conditions
[11–17].
2.1. Reagents
All the reagents and solvents were of reagent-grade quality
andpurchasedfromcommercialsuppliers. Allaqueoussolutions
were prepared with deionized water, which had been passed
through a Millipore Milli-Q Plus water purification system.
Solvent extraction is one of the most versatile procedures
among the separation techniques used for the removal and sep-
aration of metals. The development of selective extractants has
2.2. Apparatus
1H NMR spectra were recorded on a Bruker 200 MHz spec-
trometer in DMSO d6 with TMS as the internal standard. IR
spectra were recorded on a Perkin-Elmer 1605 FTIR spec-
trometer as KBr pellets. UV–vis spectra were obtained on a
∗
Corresponding author. Tel.: +90 252 2111496; fax: +90 252 2238656.
E-mail address: rgup@mu.edu.tr (R. Gup).
1386-1425/$ – see front matter © 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.saa.2006.01.004

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Scheme 1. (i) NH2NH2·H2O, reflux 2 h; (ii) isonitrosoacetophenone, EtOH, CH3COOH, reflux 4 h.
Shimadzu 1601 UV–vis spectrophotometer. Atomic absorption
spectrophotometer used to determine metal ion concentration in
the aqueous phase was DV 2000 Perkin Elber ICP-AES. Melt-
ing points were determined on an Electrothermal IA 9100 digital
melting point apparatus and are uncorrected. pH measurements
were made on a Hanna Instruments HI 8314 pH meter with a
combined glass electrode.
Isonitrosoacetophenone was synthesized as described in pre-
viously reported method [7,18,19]. Anthranoylhydrazine was
prepared by refluxing ethyl anthranilate (10 mmol, 1.48 mL)
with hydrazine hydrate (2.5 mL) for 4 h, respectively. The com-
pound separated on standing over night, filtered and washed with
distilled water. The pure hydrazine was obtained by recrystal-
liztion from hot ethanol. Scheme 1 illustrates the synthesis of
H2L. The ligand and its complexes were synthesized as follows.
in warm absolute EtOH (20 mL). The resulting green reaction
mixture was stirred at room temperature for 3 h. The precip-
itated complex was filtered off, washed with absolute ethanol
and diethyl ether, and then dried in vacuum.
2.4.2. [Cu(HL)(NO3)(H2O)]
A solution of Cu(NO3)2·3H2O (0.242 g, 1 mmol) in 10 mL of
absolute EtOH was added to a warm solution of H2L (0.282 g,
1 mmol) in absolute EtOH (20 mL) with stirring. The reaction
mixture was refluxed 1 h after adding an equivalent amount of
ethanolic solution of triethylamine (0.1 M). The resulting green
precipitate was filtered off, washed with absolute ethanol and
diethyl ether, and then dried in vacuum.
2.4.3. [{M(L)}2] (M = Ni or Cu)
A solution of Ni(AcO)2·4H2O (0.249 g, 1 mmol) or
Cu(AcO)2·H2O (0.20 g, 1 mmol) in EtOH (10 mL) was added
to a hot solution containing H2L (0.282 g, 1 mmol) and KOH
(0.112 g, 2 mmol) in EtOH (40 mL) with stirring. The reaction
mixture was refluxed for 3 h and then the volume was reduced to
∼15 mL volume under reduced pressure. The precipitated com-
plexes were filtered off, washed with small amount of cold water,
hot methanol and diethyl ether and dried in vacuum.
2.3. Isonitrosoacetophenone anthranoylhydrazone (H2L)
To a solution of anthranoylhydrazine (10 mmol, 1.51 g) in
ethanol (50 mL) was added isonitrosoacetophenone (10 mmol,
1.49 g) and two drops of glacial acetic acid. The reaction mix-
ture was stirred while refluxing for 4 h. On standing over night,
the yellow crystalline product separated, collected by filtration,
washed with small quantities of cold ethanol and diethyl ether
1
and then dried in vacuum. H NMR (DMSO d6): δ 6.91 s, 2
2.5. Solvent extraction
H ( NH2); 6.76–8.14 m, 9 H (Ar–H); 8.74 s, 1 H (C H N);
12.62 s, 1 H (NHamide); 13.10 s 1 H (O Hoxime).
The compound is soluble in DMSO, DMF, THF, acetone,
MeOH, CHCl3, CH2Cl2, slightly soluble in diethyl ether and
ethyl acetate and insoluble in water, benzene.
A 10 mL aqueous solution containing 1 × 10−4 M metal
nitrateandanappropriatebufferwascontactedwithanequalvol-
ume of the chloroform solution containing [H2L] (1 × 10−3 M)
by shaking in a mechanical shaker at 25 ◦C. The ionic strength
of the aqueous phase was kept μ = 0, 1 by adding appropriate
amount of KNO3. In the case of copper extraction, the equilib-
rium was attained in almost 10 min and a shaking time of 30 min
wassufficienttoobtainreproducibleresults. Theotherextraction
mixtures were shaked for 2 h at 25 ◦C. The extractabilities were
not affected by further shaking indicating that the distribution
2.4. Preparation of the complexes
2.4.1. [Cu(H2L)Cl2]
A solution of CuCl2·2H2O (0.171 g, 1 mmol) in 10 mL of
absolute EtOH was added to a solution of H2L (0.282 g, 1 mmol)

R. Gup, E. Gizirog˘lu / Spectrochimica Acta Part A 65 (2006) 719–726
721
Reflux
equilibrium was attained within 2 h and finally left standing for
phase separation for 10 min at room temperatures. After phase
separation, metal ions remaining in the aqueous phase were then
determined from the decrease in the metal concentration in the
aqueous phase by ICP-AES.
H2L+ Cu(NO3)2 −Et−ha−n−ol−, −b→ase Cu(HL)(NO3)(H2O)+HNO3 (3)
The 1:1 molar ratio reaction, as in Eq. (1), of H2L with
CuCl2·2H2O in absolute ethanol affords the complex (1) where
the coordination takes place in the keto form and H2L refers to
the neutral acylhydrazoneoxime ligand. The reactions (Eq. (2))
of copper(II) and nickel(II) acetates, on the other hand, with the
ligand in the presence of strong base result in precipitation of the
dimeric complexes, [{M(L)}2], (3) and (4) where both the oxime
and enolimine protons are deprotonated. The refluxing of H2L
with copper(II) nitrate in the presence of an equivalent amount
of base in EtOH, as in Eq. (3), yields green complex with stio-
chiometry [Cu(HL)(NO3)(H2O)], (2). The acylhydrazoneoxime
ligand converts to enol form in the solution and the coordination
takes place in the enolate form by deprotonating amidic pro-
ton. Attempts to isolate crystals suitable for X-ray diffraction
were unsuccessful. Therefore, UV–vis, elemental analysis and
magnetic susceptibility techniques were employed in order to
determine the structural characteristics of the complexes. The
analytical and physical data for the ligand and its complexes are
given in Table 1.
3. Results and discussion
3.1. Synthesis
The acylhydrazoneoxime ligand was synthesized by reflux-
ing anthranoylhydrazide with isonitrosoacetophenone in the
presence of glacial acetic acid in absolute ethanol. The reaction
proceeded smoothly producing the corresponding ligands in
good yields. The ligand is soluble in organic solvent such as
MeOH, DMSO, CHCl3, DMF, etc. and in hot ethanol, but
insoluble in water, Et2O and in hydrocarbon solvents. The
solvent extraction property of acylhydrazoneoxime ligand is
also examined.
Hydrazones such as synthesized in this work may exit in
the keto(I) or in the enol(II) tautomeric form in the solid state
(Fig. 1). The observation of strong ν(C O) absorption band
around 1647 cm−1 in the infrared spectra of the ligand sug-
gests that the acylhydrazoneoxime is in the keto form in the
solid state [16,17,20]. The tautomeric keto form of compound
was also indicated by 1H NMR spectroscopy since OH signal of
enol form of ligands was not observed, while amide NH signal
of keto form appeared at 2.62 ppm.
3.2. IR and 1H NMR spectra for ligand
1
In the H NMR spectra of the acylhydrazoneoxime com-
pound the resonance of the NH proton appears as a singlet at
12.62 ppm. The characteristic oxime OH proton is observed at
13.10 ppm. These chemical shifts are characteristic value for
hydrazones and oximes [3,10,21,22]. The other obtained values
Ethanol
H2L + CuCl2 −R−oo−m−−te−m−p−er−at→ure Cu(H2L)Cl2
(1)
1
for H NMR chemical shifts of hydrazone compound: NH2 at
Reflux
6.91 ppm, Ar–H at 6.76–8.14 ppm and CH at 8.74 ppm. These
data are in agreement with previously reported for similar com-
pounds [3,6,21–23].
H2L + M(AcO)2 + 2KOH −−−→ M2L2+2H2O + 2AcOK
Ethanol
(M=Ni2+or Cu2+
)
(2)
Fig. 1. Tautomeric forms of the ligand.
Table 1
Elemental analytical results and some properties of the ligands and complexes
Compound
m.p. (◦C)a
Yield (%)
B.M. (μeff
)
Elemental analyses (%) (calcd./found)
C
H
N
M
C
15H14N4O2 (H2L)
209
221
249
>300
>300
84
64
71
82
79
–
63.83/64.10
43.22/43.45
40.68/40.32
51.06/50.89
51.77/52.02
4.96/4.69
3.36/3.22
3.84/4.03
3.40/3.23
3.45/3.26
19.86/19.55
13.45/13.13
25.31/24.90
15.89/16.22
16.11/16.40
–
C15H14N4O2Cl2Cu (1)
C15H15N5O6Cu·H2O (2)
C30H24N8O4Cu2·H2O (3)
1.66
1.78
0.86
Dia.
15.25/15.09
14.35/14.71
18.01/18.30
16.22/15.92
C30H24N8O4Ni2·H2O (4)
a
Decomposition.

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R. Gup, E. Gizirog˘lu / Spectrochimica Acta Part A 65 (2006) 719–726
Table 2
IR Spectral data of the complexes (cm−1
)
Compound
ν(NH2)
ν(O H)
ν(N H)
ν(C O)
ν(ꢀC
N
N
Cꢁ)
ν(C N)
ν(C N)
ν(C O)
ν(N O)
Other
H2L
(1)
(2)
(3)
(4)
3466, 3356
3250 br
3414
3405
–
1647
1625
–
1615, 1577
1593, 1564
1554
1560
1562
1329
1347
1342
1371
1367
–
–
1179
1176
1159
1097
1087
1085
1071
1066
3202
–
1617
1618
1610
3473
3471, 3389
3468, 3381
–
–
–
–
–
–
1489, 1378, 1283
–
Fig. 2. Intramolecular hydrogen bonding of H2L.
In the IR spectra of ligand, the characteristic amide I band
appears at 1647 cm−1. The stretching vibration of the C Nimine
and C Noxime are observed at 1615 and 1577 cm−1, respec-
tively. The broad medium intensity band appearing ∼3250 cm−1
is assigned to the characteristic OHoxime absorption. The other
bands observed in the IR spectra of the ligand are given in
Table 2. These values are in accord with the previously reported
hydrazone and oxime derivatives [3,10–15,21–23].
lower field (12.62 ppm) cannot be explained by the intramolec-
ular hydrogen bonding but may be explained by the inter-
molecular hydrogen bonding since the amide and carbonyl
groups of H2L can bond by intermolecular hydrogen bond-
ing to produce dimmer with an s-cis conformation (Fig. 3)
[24,25].
The IR spectra of isonitrosoacetophenone anthranoyl-
hydrazone exhibits a very broad medium intensity peak
3300–2600 cm−1 region, which are assigned to the intramolec-
ular H-bonding vibration (O–H · · · N) [21,22,24]. Also the
amide NH stretching band of H2L was not observed in the
IR spectra probably due to overlapping with the intermolecu-
lar hydrogen-bonded OH stretching frequency. In the 1H NMR
spectra of H2L, two absorption bands, which are assigned the
oxime OH and amide NH protons, appear at lower field, at
12.62 and 13.10 ppm due to hydrogen bonding. Several isomers
which have intramolecular hydrogen bonding can be possi-
ble for the synthesized acylhydrazoneoxime compound (H2L)
in this study (Fig. 2). According to IR and 1H NMR data,
isomer B is more suitable owing to the position of strong
intramolecular hydrogen bonding (O–H · · · N); therefore, we
attributed the peaks appearing at 13.10 and 12.62 ppm for
oxime OH proton and amide NH proton, respectively. How-
ever, the shift of the amide NH proton absorption to relatively
Fig. 3. s-cis Conformation of H2L.

R. Gup, E. Gizirog˘lu / Spectrochimica Acta Part A 65 (2006) 719–726
723
Fig. 4. Suggested structures for the monomeric copper complexes.
of three strong bands at 1489, 1378 and 1283 cm−1 correspond-
ing to ν1, ν−2 and ν4 of nitrato group indicates the participa-
tion of NO3 group in complexation [21,29]. According to IR
data and the elemental analysis result, the structures proposed
for dimeric copper (3) and nickel (4) complexes are given in
Fig. 5.
3.3. IR spectra for complexes
To determine the mode of the ligand coordination with metal
ions, we compared the IR spectra of the metal free acylhydrazo-
neoxime ligand with that of the complexes. The infrared absorp-
tion bands of the complexes are given and assigned in Table 2. A
series of bands assigned to ν(C O), ν(C N)imine, ν(C N)oxime
,
ν(N H), ν(O H), ν(C N) and ν(N O) are observed in the IR
spectra of the dichloro complex [Cu(H2L)Cl2] (1). Comparing
these data with those of the free ligand it is obviously seen that
amide I [ν(C O)], ν(C N)imine, ␯(C N)oxime and ν(N O) bonds
shifted to lower frequencies, whereas ν(C N) absorptions are
moved to higher frequencies. The amide NH stretching vibration
which is not clearly seen in the IR spectra of the metal free ligand
appears as a medium band at 3202 cm−1. The oxime OH absorp-
tion band in the IR spectra of the dichloro complex becomes
narrow and shifts to higher frequency suggesting disappearance
ofintramolecularhydrogenbondingandnon-involvementofthis
group in coordination. According to IR data and stoichiometry
of this complex, the ligand acts as a neutral O,N,N-tridentate
ligand (Fig. 4).
The IR spectra of the complexes (2), (3) and (4) lack absorp-
tions due to amide I [ν(C O)], ν(C Nimine) and ν(N H), but
show two new bands at ∼1617 and ∼1163 cm−1 probably due
to ꢀC N N Cꢁ and C O stretching, respectively, suggesting
that the NH proton is likely lost via deprotonation induced
by the metal and the resulting enolic oxygen and the azome-
thine nitrogen take place in coordination [16,21,22,26,27]. The
band at ∼1617 cm−1 is intense and broad and can be attributed
to overlapping of ꢀC Nimine band stretch of the free ligand
with the newly formed N Cꢁ bond stretching during com-
plexation. The absence of OH stretching vibration for dimeric
complexes [(3) and (4)] indicates the deprotonation of the
oxime OH and participation in coordination by resulting oxy-
gen atom to produce dimeric structure. Upon coordination of
metal ion, stretching vibration of the oxime C N is shifted to
lower frequency relative to that of the metal free ligand indi-
cating the coordination of the oxime C N group to a metal
ion. The IR spectrum of the nitrate complex (2) displays a
broad band at 3405 cm−1 probably due to stretching vibration
of free oxime OH group [16,28]. Furthermore, the observation
3.4. Magnetic susceptibility
The magnetic moment data of the solid-state complexes at
room temperature are reported in Table 3. Magnetic suscepti-
bility value for dimeric nickel complex [{Ni(L)}2] is consistent
with diamagnetic structure given to the low spin d8 complex.
However, the room temperature magnetic moment of the dimeric
copper(II) complex [{Cu(L)}2] is much lower than expected for
spin-only value. This can be explained by the strong antiferro-
magnetic interaction between the two copper(II) centers in the
dimeric structure as expected for all the dicopper(II) oximato
complexes [14,16,17]. Dichloro copper (1) and nitrate copper
(2) complexes, however, are mononuclear since their effective
magnetic moments correspond to the spin value for one unpaired
electron [16,17,22].
Fig. 5. Suggested structures for the dimeric complexes, [{M(L)}2].

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Table 3
Electronic spectral data (nm) of H2L and its complexes
Compound
MeOH
EtOH
CH2Cl2
CHCl3
DMF
H2L
(1)
(2)
(3)
(4)
374, 331, 234
372, 334, 237
365, 336, 238
365, 335, 244
457 sh, 387, 247
Insoluble
Insoluble
483 sh, 422, 344, 245
375, 337, 266, 237
461 sh, 381, 287, 269, 237
457 sh, 389, 255, 244
476 sh, 389, 289, 245
462 sh, 416, 318 sh, 270
sh, shoulder.
3.5. Electronic absorption spectra
of the compound. The observation of the isosbestic point can be
another evidence for the formation of cationic from in the acidic
media.
The electronic spectra for acylhydrazoneoxime ligand
recorded in various solvents are given in Table 3. The band of
shortest wavelength appearing at ∼240 nm may be attributed
␲ → ␲* transition of benzenoid moiety of the ligand. The other
two bands observed at ∼335 and ∼370 nm for H2L are attributed
On the other hand, the electronic spectra of H2L in both
neutral alcoholic and highly basic solutions show considerable
different absorption pattern (Fig. 7). The λmax of the acylhydra-
zoneoxime shows a slight blue shift at high pH values (>11.45),
while the band which appears at 333 nm in neutral and slightly
basic solutions disappears at pH 9.62 and higher values probably
owing to the deprotonation of the acylhydrazone part. Further-
more, a new band which is absent in the base free solutions is
observed at ∼281 nm in the basic solutions. As the pH values
of solutions increase, the intensity of this band increases. This
band may indicate that the acylhydrazoneoxime ligand exists
in the anionic form in basic solutions probably due to oxime
(C N OH) group.
*
n → ␲ electronic transitions.
3.5.1. Solvent and pH effects on the electronic spectra of
H2L
The effect of varying solvent for absorption spectra of H2L
was studied in organic solvents of various polarities EtOH,
MeOH, CHCl3, CH2Cl2 and DMF. It is observed that the absorp-
tion spectra of acylhydrazoneoxime are considerably influenced
by changing the solvent. The λmax of H2L shows regular red
shift with change in the polarities of solvents; λmax is 365 nm in
CHCl3 and CH2Cl2, 372 nm in CH3CH2OH, 354 nm in CH3OH
and 375 nm in DMF.
The effect of pH change for absorption spectra of H2L was
also performed by adding HCl or KOH in EtOH solution (Fig. 6).
The λmax of the ligand acquires a blue shift while the intensity of
the band appearing at 333 nm increases at low pH values relative
to its position in neutral and slightly acidic solutions. The band
observed at 372 nm in neutral media finally disappears at very
low pH values (<1.23). This phenomenon can be explained that
the acylhydrazoneoxime ligand exists in the cationic form in the
highly acidic media due to protonation on probably amino side
3.5.2. Electronic absorption spectra of the complexes
Electronic absorption spectra of the complexes were recorded
in DMF solution (Table 3) (Fig. 8). By comparison of the elec-
tronic absorption spectra of the free ligand and its complexes, it
is observed that the band appearing at 375 nm in DMF solution
of the metal free ligand shows a red shift and appears around
390 nm. However, the band appearing at 337 nm in the free lig-
and disappears or is observed as a shoulder with a blue shift.
Furthermore, in the electronic spectra of all complexes there is
a band in the visible region, which is usually a shoulder. This
band can be attributed to LMCT transition. Unfortunately the
Fig. 6. Absorption spectra of H2L in acidic solutions (EtOH): (1) pH 7.11; (2)
pH 5.05; (3) pH 4.13; (4) pH 2.93; (5) pH 2.11; (6) pH 1.80; (7) pH 1.40; (8)
pH 1.23; (9) pH 1.07; and (10) pH 0.97.
Fig. 7. Absorption spectra of H2L in basic solutions (EtOH): (1) pH 7.11; (2)
pH 7.90; (3) pH 8.47; (4) pH 9.04; (5) pH 9.62; (6) pH 10.38; (7) pH 11.45; (8)
pH 12.00; (9) pH 12.93; and (10) pH 13.11.

R. Gup, E. Gizirog˘lu / Spectrochimica Acta Part A 65 (2006) 719–726
725
Fig. 9. The effect of pH on the extraction of copper(II) by H2L [pH
2.2 (NaNO3/HNO3); pH 3.8, 4.5 and 5.4 (CH3COONa/CH3COOH); pH
5
(CH3COONa/HCl); pH 6.4 and 7.4 (NaH2PO4/Na2HPO4); pH 8.5
Fig. 8. Electronic absorption spectra of the complexes in DMF: (a)
[Cu(H2L)Cl2]; (b) [(CuL)2]; (c) [(NiL)2]; and (d) [Cu(HL)(NO3)H2O].
(NaHCO3/Na2CO3) and pH 9.5 (NH3/NH4Cl)].
group is a soft base owing to its contribution to cation-п interac-
tion;therefore, showsahighaffinitytowardsoftacidiccopper(II)
cation [8,9,30–33].
expected weak d–d transition in the visible region for all com-
plexes cannot be detected even with concentrated solution. It
may be lost in the low energy tail of the charge transfer transi-
tion [21,22].
4. Conclusion
3.6. Extraction ability of the ligand
In this work the synthesis and characterization of the
mononuclear copper(II) and nickel(II) complexes as well
as binuclear copper(II) and nickel(II) complexes derived
from acylhydrazoneoxime ligand, isonitrosoacetophenone 2-
aminobenzoylhydrazone. The reaction of isonitrosoacetophe-
none 2-aminobenzoylhydrazone (H2L) with CuCl2·H2O yields
the complex [Cu(H2L)Cl2] where the ligand acts as a neu-
tral O,N,N-tridentate and the coordination takes place in the
keto form. On the other hand, when the reaction is performed
between the ligand and Cu(NO3)2·3H2O in the presence of
an equivalent amount of base, the complex with stiochiometry
[Cu(HL)(NO3)(H2O)] is synthesized where the ligand acts as a
monobasic O,N,N-tridentate and the coordination takes place in
the enol form. The acylhydrazoneoxime ligand reacts with cop-
per(II) and nickel(II) acetates in the presence of the strong base
to produce common bimetal(II) oximato complexes, [{M(L)2}]
in which two copper(II) or nickel(II) atoms are bridged through
two N O bridges of the oximato ligand to afford a binuclear
structure. The absorption spectrum of the acylhydrazoneoxime
ligand is influenced by varying both pH and solvent.
The results of the liquid–liquid extraction study towards
selected transition metal (Cu2+, Ni2+, Co2+, Cr3+, Hg2+,
Zn2+, Cd2+ and Mn2+) presented in this work show that the
acylhdrazoneoxime ligand has strong affinity towards cop-
per(II) ion whereas the ligand is very poor extractant for
the other transition metals. This can make this ligand suit-
able selectively separating Cu(II) ion. However, the low sol-
ubility of this compound especially in the kerosene type of
diluents may be disadvantage, therefore, it may be needed
some modifications in order to enhance solubility. It is also
believed that the affinity and selectivity of isonitrosoacetophe-
none 2-aminobenzoylhydrazone towards copper(II) ion can be
increased by the investigation and changing the extraction con-
ditions such as ionic strength, foreign ion effect, ligand concen-
tration and solubility, temperature, solvent effect, etc.
Solvent extraction of copper has become an important pro-
cess. Several commercial reagents some of which are phenolic
oximes derived from salicylaldehyde or ketophenols have been
used for copper recovery from sulphate, chloride, nitrate or
ammonia media [1,2,4,8,9,25]. In order to confirm whether this
compound can be used for extraction reagent, we studied the
complexation ability of the synthesized acylhydrazoneoxime
compound by the liquid–liquid extraction of selected transition
metal (Ni2+, Cu2+, Co2+, Cd2+, Zn2+, Mn2+, Hg2+ and Cr3+)
cations. The results are given in Table 4. Due to the insolubility
of the ligand in kerosene-type diluents, these data were obtained
by using CHCl3 solutions of the ligand to extract metal nitrates
from aqueous solution. The concentration of metals remaining
in the aqueous phase was then determined by ICP-AES.
The effect of the pH on the percentage extraction of cop-
per(II) by H2L in chloroform was studied in the range of 2.5–9.5
under the optimum extraction conditions. As shown in Fig. 9, the
highest extraction percentage of Cu(II) was observed at pH 5.
Therefore, the experiments were carried out at this pH by using
suitable buffer solutions with 0.1 M KNO3 ionic strength.
It is observed from Table 4 that the acylhydrazoneoxime lig-
and shows selectivity toward Cu2+ cation. This result can be
explained by the hard soft acid–base principle. The C N OH
Table 4
Extraction of metal nitrates with the synthesized compounda
Compound The extracted metal cations (%)
Cu2+ Ni2+ Co2+ Cd2+ Mn2+ Zn2+ Hg2+ Cr3+
H2L
98.6
1.8
1.2
1.3
<1
<1
2.0
8.3
a
Aqueous phase; [metal nitrate] = 1 × 10−4 M; organic phase; chloroform
[ligand] = 1 × 10−3 M; at 25 ◦C for 10 min for Cu(II) extraction and 2 h the other
extractions.

726
R. Gup, E. Gizirog˘lu / Spectrochimica Acta Part A 65 (2006) 719–726
[15] S.P. Wan, H. Kuma, S. Yamada, Synth. React. Inorg. Met. -Org. Chem. 16
Acknowledgement
(1986) 1273.
[16] M.F. Iskander, L.E. Sayed, N.M.H. Salem, R. Werner, W. Haase, J. Coord.
Chem. 56 (2003) 1075.
[17] M.M. Aly, N.I. Al-Shatti, Transition Met. Chem. 23 (1998) 361.
[18] H.I. Ucan, R. Mirzaoglu, Synth. Rect. Inorg. Met. -Org. Chem. 20 (1990)
437.
[19] J.J. Norman, R.M. Heggie, J.B. Larose, Can. J. Chem. 40 (1962)
1547.
[20] R.A. Lal, M.L. Pal, S. Adhikari, S. Synth. React. Inorg. Met. -Org. Chem.
26 (1996) 997.
[21] R. Gup, Russ. J. Coord. Chem. 32 (2) (2005) 1.
[22] R. Gup, B. Kırkan, Spectrochim. Acta A 62 (4–5) (2005) 1188.
[23] L.L. Koh, O.L. Kon, Y.C. Loh, J.D. Ranford, A.L.C. Tan, Y.Y. Tjan, J.
Inorg. Biochem. 72 (1998) 155.
[24] F.V. Bagrov, T.V. Vasil’eva, Russ. J. Org. Chem. 38 (2002) 1364.
[25] S.N. Shetti, A.S.R. Nurty, G.L. Tembe, Indian J. Chem. 32A (1993)
511.
[26] R. Dinda, P. Sengupta, S. Ghash, T.C.M. Mak, Inorg. Chem. 41 (2002)
1684.
[27] A. Sreekanth, C.R. Nayar, M.R.P. Kurup, Polyhedron 23 (2004)
41.
This work was supported by the Research Fund of Mugla
University, Mugla, Turkey.
References
[1] L. Calligaro, A. Mantovani, U. Belluco, M. Acampora, Polyhedron2(1983)
1189.
[2] A.W. Ashbrook, Coord. Chem. Rev. 16 (1975) 285.
[3] K.H. Reddy, N.B.L. Prasod, T.S. Reddy, Talanta 59 (2003) 425–433.
[4] L.C. Emeleus, D.C. Cupertino, S.G. Harris, S. Owens, S. Parsons, R.M.
Swart, P.A. Tasker, D.J. White, J. Chem. Soc., Dalton Trans. (2001) 1239.
[5] L.L. Koh, O.L. Kon, Y.C. Loh, J.D. Ranford, A.L.C. Tan, Y.Y. Tjan, J.
Inorg. Biochem. 72 (1998) 155.
[6] A.M. Khambekar, A.D. Sawant, Indian J. Chem. 36A (1997) 459.
[7] V.S. Misra, S.R. Varma, J. Indian Chem. Soc. 39 (1962) 763.
¨
[8] O. Dalman, M. Tu¨fekc¸i, S. Nohut, S. Gu¨ner, S. Karabo¨cek, J. Pharm.
Biomed. Anal. 27 (2002) 183.
¨
[9] S. Karabo¨cek, S. Nohut, O. Dalman, S. Gu¨ner, Anal. Chim. Acta. 408
(2000) 163.
[28] J.A. Bertrand, J.H. Smith, P.G. Van Derveer, Inorg. Chem. 16 (1997)
1477.
[10] W. Kaminsky, J.P. Jasonsli, R. Woudenberg, K.I. Goldberg, D.J. West, Mol.
Struct. 608 (2002) 135.
[29] A.H. Al-Kubaisi, Bull. Korean Chem. Soc. 25 (2004) 37.
[30] F.J. Alguacil, A. Coba, M. Alonso, J. Chem. Eng. 85 (2002) 259.
[31] R. Gup, H.K. Alpoguz, A.D. Beduk, Collect. Czech. Chem. Commun. 67
(2002) 209.
[32] K. Srinivasa Rao, N.N. Devi, B.R. Reddy, Hydrometallurgy 57 (2000) 269.
[33] H. Deligo¨z, M. Yılmaz, Solvent Extr. Ion Exch. 13 (1995) 19.
[11] J.A. Bertrand, J.H. Smith, P.G. Eller, Inorg. Chem. 13 (1974) 1649.
[12] R.J. Butcher, C.J. O’Connor, E. Sinn, Inorg. Chem. 18 (1979) 1913.
[13] F. Abraham, J.M. Capon, G. Nowogrocki, S. Sueur, Polyhedron 4 (1985)
761.
[14] M. Maekawa, S. Kitagawa, Y. Nakao, S. Sakamoto, A. Yatani, W. Mori, S.
Kashino, M.S. Munakata, Inorg. Chim. Acta. 293 (1999) 20.