Synthesis, crystal structure, theoretical study and application of 1-(4-methylphenyl)-3-(2- (trifluoromethyl)phenyl)triaz-1-ene 1-oxide in the extraction of Ni ions: Synthesis of a new triazene 1-oxide derivative, X-ray crystal structure and its theoretical studies

Article abstract of DOI:10.1007/s13738-020-02132-5

The crystal structure of 1-(4-methylphenyl)-3-(2-(trifluoromethyl)phenyl)triaz-1-ene 1-oxide (L) is monoclinic and has a space group of P2₁/c with a = 8.066(2) ?, b = 16.740(5) ?, c = 11.730(4) ?, β = 117.76(3)° and Z = 4. In this study, direct procedures were used to solve the crystalline structure of this complex and refine it by full-matrix least-squares to ultimate values of R1 = 0.0610 and wR2 = 0.1661 with 1474 reflections (I > 2σ(I)). The molecule is included in inter-hydrogen bonding with C₅–H₅ acting as donors and O atoms of N-oxide groups as acceptors (O₁······H₅) with a distance of 2.638 ?. These results were also confirmed by theoretical studies. The spectrophotometric titrations of the synthesized L with metal ions showed a substantially greater stability constant for its nickel ion complex with a mole ratio equal to 1. Consequently, the ligand was used for the selective extraction and spectrophotometric determining the Ni²⁺ ion in natural water. Under optimized conditions, the calibrating curve was linear over a nickel concentration range of 9.2 × 10^?7–8.4 × 10^?3 M. The detecting limit of this method was 6.0 × 10^?7 M Ni²⁺. No considerable interference was found from at least 100 times concentrations of a number of possibly interfering ions.

Full text of DOI:10.1007/s13738-020-02132-5

Journal of the Iranian Chemical Society
https://doi.org/10.1007/s13738-020-02132-5
ORIGINAL PAPER
Synthesis, crystal structure, theoretical study and application
of 1‑(4‑methylphenyl)‑3‑(2‑ (triꢀuoromethyl)phenyl)triaz‑1‑ene
1‑oxide in the extraction of Ni ions
Synthesis of a new triazene 1‑oxide derivative, X‑ray crystal structure and its theoretical
studies
Behrooz Rezaei1 · Mehrnoosh Fazlollahi1
Received: 3 January 2020 / Accepted: 29 November 2020
©
Iranian Chemical Society 2021
Abstract
The crystal structure of 1-(4-methylphenyl)-3-(2-(triꢀuoromethyl)phenyl)triaz-1-ene 1-oxide (L) is monoclinic and has a
space group of P2 /c with a=8.066(2) Å, b=16.740(5) Å, c=11.730(4) Å, β=117.76(3)° and Z=4. In this study, direct
1
procedures were used to solve the crystalline structure of this complex and reꢁne it by full-matrix least-squares to ultimate
values of R1=0.0610 and wR2=0.1661 with 1474 reꢀections (I>2σ(I)). The molecule is included in inter-hydrogen bond-
ing with C –H acting as donors and O atoms of N-oxide groups as acceptors (O ······H ) with a distance of 2.638 Å. These
5
5
1
5
results were also conꢁrmed by theoretical studies. The spectrophotometric titrations of the synthesized L with metal ions
showed a substantially greater stability constant for its nickel ion complex with a mole ratio equal to 1. Consequently, the
2
+
ligand was used for the selective extraction and spectrophotometric determining the Ni ion in natural water. Under opti-
−7
−3
mized conditions, the calibrating curve was linear over a nickel concentration range of 9.2×10 –8.4×10 M. The detecting
−
7
2+
limit of this method was 6.0×10 M Ni . No considerable interference was found from at least 100 times concentrations
of a number of possibly interfering ions.
Keywords Triazenes · X-ray structure · Hydrogen bond · Solution studies · Extraction · Ni2+
Introduction
conꢁguration in the ground mode [3]. Hydroxytriazenes as
the single crystal are transformed into N-oxide form and
represent the structure’s tautomeric form. Kuroda [4] syn-
thesized 3-(4-carbamoylphenyl)-1- methyltriazene 1-oxide
and reported anti-tumor activity of this group of compounds
in hydroxyl and N-oxide forms. The N-oxide instead of
N–hydroxyl form is adopted by the molecule consistent with
the X-ray and spectroscopic evidence.
Over the last 130 years, numerous compounds such as
1
,2,3-triazene moieties have been studied for their interest-
ing structural, biological, pharmacological, and reactivity
features. These compounds are utilized in combinatorial
chemistry, medicinal, organometallic ligands, and in natural
synthesis [1]. Meldola (1887) performed the ꢁrst compre-
hensive study on a triazene derivative’s coordination chem-
istry (1,3-diphenyltriazene) [2].
This study is the continuation of our previous works
on the synthesis, complexation, and theoretical studies of
a new triazene derivative—i.e., 1-(4-methylphenyl)-3-(2-
(trifluoromethyl)phenyl)triaz-1-ene 1-oxide (Scheme 1)
The main characteristic of the triazene compounds is hav-
ing a diazoamino group (–N = NN) normally with a trans
[
5–7]. Similar to the speciꢁc complexing ability of triazene
derivatives toward transition metal ions, it was found that the
*
Behrooz Rezaei
absorbance of the title compound (L) leads to a consider-
2
+
rezaei128@yahoo.com; rezaei_b@lu.ac.ir
able decrease upon addition of Ni ion in a selective man-
ner. Thus, the analytical application of ligand L is studied
1
Department of Chemistry, Lorestan University,
Khorramabad, Iran
Vol.:(0
1
123456789)
3

Journal of the Iranian Chemical Society
0
9 package [10]. The electronic density of state (DOS) for
the optimized structures of monomer and dimer was done
using GaussSum03. Gap energy (Eg) was calculated based
on DOS results:
Eg = ELUMO− EHOMO
where E
is the energy of highest occupied molecular
HOMO
orbital (HOMO), and E
is the energy of lowest unoc-
LUMO
cupied molecular orbital (LUMO). The NBO analysis was
done to estimate the natural charge distribution around the
dimer of molecule.
Scheme 1 Chemical structure of the title compound
regarding the selective extraction and spectrophotometric
2
+
determining of Ni ion in aqueous solutions.
Results and discussion
Synthesis of 1‑(4‑methylphenyl)‑3‑(2‑(triꢀuoromet
hyl) phenyl) triaz‑1‑ene 1‑oxide
Experimental
Reagent
The ligand L was synthesis with essentially the same method
reported elsewhere for the synthesis of its isomer, with some
modiꢁcations [7]. Zinc dust (35 g) and ammonium chloride
Analytical-grade reagents including n-Hexane, chloroform,
acetonitrile, ethanol, ether, carbon tetrachloride, and carbon
tetrachloride (from Merck or Aldrich) were used without
any further puriꢁcation. The materials for the synthesis
(
16.0 g) were used to reduce an aqueous-alcoholic (2:1)
solution with 0.2 M (26.47 g) of 4-nitrotoluene at 60–65 °C.
Zinc dust was completely added in around 1 h. Next, the
obtained N-hydroxy-4-methylaniline was combined with
the diazotized product of 2-aminobenzotriꢀuoride 0.1 M
(
4-nitro toluene and 2-aminobenzotriꢀuride) were bought
from Fluka and used as received. All bases and acids, which
had the maximum purity, were purchased from Merck and
utilized as received. Throughout the tests, deionized double-
distilled water was utilized. Nitrate salts of other cations
(
12.39 ml) at 0-5 °C. It led to a yellowish-brown precipitate
ꢁ
ltered under suction that was rinsed with ice-cold water.
Ethanol was used twice to recrystallize the crude product,
and yellow needles were attained (the yield of almost 60%).
The compound’s m.p. was 115 °C.
(
all from Merck) and analytical grade nickel(II) nitrate had
the maximum available purity and utilized without further
puriꢁcation, expect vacuum drying. The normal stock solu-
tion of Ni(II) was prepared by dissolving a proper quantity of
nickel(II) nitrate in 2 mL concentrated nitric acid and dilut-
ing it to 100 mL with water. The stock solution was diluted
appropriately to prepare working solutions.
To prepare appropriate single crystals, a branched tube
technique was used. The title compound (0.2 g) was located
in one arm of a branched tube and both arms were ꢁlled by
adding n-Hexane carefully. Then, the tube was sealed and
the arm comprising ligand was submerged in a bath at 50 °C,
while the other arm was maintained at ambient temperature.
The crystals were deposited in the cooler arm after 5 days
during which the arm was ꢁltered-oꢂ, rinsed with ether, and
dried in the air [5, 6].
Apparatus
A Shimadzu spectrophotometer with (Japan) model 1650PC
double-beam was utilized to run the electronic absorption
spectra. The pH modiꢁcations were performed using the
Jenway pH meter (model 3020) equipped with an integrated
glass-calomel electrode.
X‑ray crystallographic structure of 1‑(4‑methylphen
yl)‑3‑(2‑(triꢀuoromethyl)phenyl)triaz‑1‑ene 1‑oxide
Computational details
Crystallographic measurements were performed at 293(2)
K utilizing a Nonius kappa-CCD diffractometer. Using
direct approaches, the structure of 1-(4-methylphenyl)-3-
(2-(triꢀuoromethyl)phenyl)triaz-1-ene 1-oxide was solved
Structures of the title compound in two conformations and in
dimer form were optimized using B3LYP [8, 9] method and
also exchange and association functional with 6-311 g(d,p)
base set. The vibrational frequencies were done at the identi-
cal level of theory to conꢁrm all structures are in global min-
imum. All calculations were completed using the Gaussian
2
and reꢁned via full-matrix least-squares methods on F uti-
lizing SHELXTL. [11] The values of geometric parameters
of the title compound are in standard experimental errors
and ranges. The title compound’s geometric parameters are
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Journal of the Iranian Chemical Society
within the common ranges. It is crystallized in the mon-
Table 2 Atomic coordinates and equivalent isotropic displacement
2
parameters [in Å ] for 1-(4-methylphenyl)-3-(2-(triꢀuoromethyl)phe-
oclinic system, space group P2 /c with a = 8.066(2) Å,
1
nyl)triaz-1-ene 1-oxide. U(eq) is deꢁned as one third of the trace of
the orthogonalized Uij tensor
b=16.740(5) Å, c=11.730(4) Å, β=117.76(3)° and Z=4.
With 1474 reꢀections, the crystal structure was solved to
ultimate values wR2=0.1661 and R1=0.0610 (I>2σ(I).
The N–H hydrogen atom was placed in a Fourier map
with a diꢂerent density to reꢁne its locations at a stand-
ard deviation of 0.02 Å and an N-H distance of 0.86 Å.
All other hydrogen atoms were placed in the assigned loca-
tions. Also, all H atoms were reꢁned considering an iso-
tropic displacement parameter of 1.5 (methyl) or 1.2-times
Atom
X
Y
Z
U(eq)
O(1)
N(1)
N(2)
N(3)
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
C(7)
F(1)
0.0216(3)
0.0785(3)
0.1942(3)
0.1562(3)
0.0953(4)
0.2396(4)
0.2548(5)
0.1274(5)
−0.0143(5)
−0.0323(4)
−0.1875(5)
−0.3046(4)
−0.2951(4)
−0.1333(5)
0.2694(4)
0.4184(4)
0.5221(5)
0.4805(5)
0.3306(5)
0.2238(5)
0.5990(6)
0.27238(13)
0.41558(14)
0.37985(14)
0.30580(14)
0.49725(16)
0.54016(16)
0.62114(18)
0.66083(19)
0.61873(19)
0.53748(17)
0.49481(18)
0.4604(2)
0.54017(17)
0.4345(2)
0.26017(16)
0.29470(18)
0.2492(2)
0.1040(3)
0.1509(2)
0.1145(2)
0.0925(2)
0.1755(2))
0.1717(3)
0.1949(3)
0.2218(3)
0.2275(3)
0.2050(3)
0.2112(3)
0.1010(3)
0.2413(4)
0.2928(4)
0.0508(3)
0.0428(3)
0.0010(3)
−0.0326(3)
−0.0237(3)
0.0173(3))
−0.0738(4)
0.0913(8)
0.0669(7)
0.0627(7)
0.0655(7)
0.0585(7)
0.0675(8)
0.0789(9)
0.0815(10)
0.0788(9)
0.0657(8)
0.0904(10)
0.1379(14)
0.1405(14)
0.1609(17)
0.0638(8)
0.0752(9)
0.0832(10)
0.0810(10)
0.0864(10)
0.0768(9)
0.1174(15)
(
all others) isotropic displacement parameter of the nearby
nitrogen or carbon atom. Table 1 represents the equivalent
structural reꢁnements and crystal. Also, Table 2 provides all
atomic coordinates and corresponding isotropic displace-
ment parameters.
The crystal contains discrete molecules (Fig. 1a). The
torsion angles of C(1)-N(1)-N(2)-N(3) and N(1)-N(2)-N(3)-
C(8) are—178.2(2)° and 179.3(2)°, and the triaz-1-ene group
is planar. According to Fig. 1b, the molecules are included
F(2)
F(3)
C(8)
C(9)
C(10)
C(11)
C(12)
C(13)
C(14)
in inter-hydrogen bonding with C –H acting as donors and
5
5
0.1696(2)
0.1370(2)
0.18116(18)
0.1207(3)
Table 1 Crystal data and structure reꢁnement details for 1-p-tolyl-3-
3-(triꢀuoromethyl)phenyl)triaz-1-ene-1-oxide
(
Chemical formula: C H F N O
14
12
3
3
Formula weight=295.27
T=293(2) K
Estimated standard deviations are given in parentheses
Crystal system: monoclinic
a=8.066(2) Å
b=16.740(5) Å
space group: P21/c
α=90.00
β=117.76(3)
γ=90.00
N-oxide groups’ O atoms as acceptors (O ······H ) with a
1
5
distance of 2.638 Å. Packing the resultant crystal (Fig. 2)
demonstrates the creation of a one-dimensional network.
This network is attributed to the existence of intermolecular
weak hydrogen bonding and C –H ······F interactions with
c=11.730(4) Å
V=1401.6(7) Å3
Z=4
3
D =1.453 g/cm
x
9
9
1
Radiation: Mo Kα (λ=0.71069 Å)
the distance of 2.626 Å between the neighboring molecules,
which are responsible for the one-dimensional framework of
the crystal. Table 3 provides the equivalent distances for the
hydrogen bonds. Moreover, face-to-face π-π stacking inter-
actions exist within aromatic rings of the nearby chains in
this compound.
−1
µ(Mo K )=0.118 mm
F(000)=608
a
Crystal size=0.60×0.45×0.40 mm
No. of reꢀections collected=3911
No. of independent reꢀections=2000
θ range for data collection: 1.0 to 23.3°
Data/restraints/parameters=2000/60/220
2
Goodness-of-ꢁt on F =1.040
Theoretical studies
R indices [I>2σ(I)]: R1=0.0610,
wR2=0.1661
Figure 3 presents the optimized structures of the title com-
pound in two enol and enoxide forms.
R indices (all data): R1=0.0810,
wR2=0.1848
The results of geometry optimization and energy analysis
show that structure A is more stable than B. This result is
in accordance with experimental observations. To study the
hydrogen bonding formation between two monomers, the
structure of its dimer was optimized, which its geometry is
illustrated in Fig. 4.
(
(
Δ/δ)max =0.001
Δρ)max =0.353 eÅ
−
3
(Δρ)min =-0.228 eÅ−3
Measurement: Nonius kappa-CCD
diꢂractometer
Program system: SHELXL-97
Structure determination: SIR97
CCDC deposition number: 721301
The optimized geometry of dimer shows that the hydro-
gen bonding formed between the hydrogen of the phenyl
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Journal of the Iranian Chemical Society
Fig. 1 a ORTEP representation and b showing hydrogen bonding in the compound 1-(4-methylphenyl)-3-(2-(triꢀuoromethyl)phenyl)triaz-1-ene
1
-oxide
group in one monomer and O and F in the other monomer.
The IR spectrum of this dimer is shown in Fig. 5.
The lack of imaginary frequency in the calculated IR
spectrum conꢁrms the stability of the structure of this dimer.
Using the optimized structures of monomer and dimer, the
DOS spectra for them was calculated. The result of DOS
calculation is illustrated in Fig. 6.
analysis was done to estimate the charge distribution around
its structure. In Fig. 7, the result of NBO analysis is shown.
As depicted in NBO analysis, the hydrogen atoms which
contribute in hydrogen bonding formation have positive val-
ues (+0.235 and +0.215) and the oxygen and ꢀuorine atoms
contributed in hydrogen bonding formation have negative
values (-0.557 and -0.362). From the NBO analysis, it can
be estimated that the hydrogen bonding between the hydro-
gen and oxygen atoms has relatively more strength than
the hydrogen bonding created between the hydrogen and
ꢀuorine atom. The HOMO and LUMO proꢁle of the dimer
structure were calculated, which is illustrated in Fig. 8.
Employing the DOS spectra the HOMO and LUMO
energies were calculated and the results of E = 3.73 and
g
E =3.29 were obtained for monomer and dimer structures,
g
respectively. A minor reduction of E was observed in
g
dimerization of the structure. For dimer structure, the NBO
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Journal of the Iranian Chemical Society
Fig. 2 Packing and O···N
and F···H interactions shown
between the parallel molecules
in the 1-(4-methylphenyl)-3-(2-
(
triꢀuoromethyl)phenyl)triaz-1-
ene 1-oxide
Table 3 Hydrogen bond distances (in Å) of 1-(4-methylphenyl)-3-(2-
Spectral features
(
triꢀuoromethyl)phenyl) triaz-1-ene 1-oxide
d(D-H)
d(H…..A)
d(D….A)
Complexing the molecule 1-(4-methylphenyl)-3-(2-
(
triꢀuoromethyl)phenyl)triaz-1-ene 1-oxide by increasing
C –H …O
1
d=0.931
d=0.930
d=2.638
d=2.626
d=3.261
d=3.425
5
5
the concentration of the various metal ions was evaluated
spectrophotometrically at room temperature in acetonitrile
solution. For the sake of simplicity, we indicated only the
C –H …F
1
9
9
2
+
absorption spectra of the title compound known as Ni . As
can be seen from Fig. 9, the robust absorption of the ligand
at about 350 nm declined by increasing the concentration
The results of Fig. 8 show that the HOMO orbital
mainly located on the specie which have hydrogen of
hydrogen bonding and LUMO orbital mostly located on
the specie having the oxygen and fluorine atoms.
2
+
of the Ni . Figure 10 presents the resulting absorbance as
a function of [metal ion]/[triazene] mole ratio for diꢂer-
ent metal ions. According to Fig. 10, for most of the other
2
+
+
2+
2++
2+
investigated metal ions, i.e., Pb , Ag , Mn , Cd , Hg ,
2+
2+
2+
Cu , Co , and Zn , small or insigniꢁcant variations in the
Fig. 3 The structures of title compound in enol (A) and enoxide (B) forms
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Journal of the Iranian Chemical Society
Fig. 4 The optimized structure of the dimer of title compound
Fig. 5 Calculated IR spectrum
of the dimer
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Journal of the Iranian Chemical Society
Fig. 6 The results of DOS calculation for the monomer and dimer structures
Fig. 7 The NBO analysis of dimer structure
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Journal of the Iranian Chemical Society
Fig. 8 The HOMO and LUMO proꢁles of the dimer structure
−5
Fig. 10 Absorbance of a 5×10 M of L ligand solution at about
3
50 nm, as a function of metal ion/triazene mole ratio for diꢂerent
metal ions
−
5
Fig. 9 Absorbance spectra of a 5×10 M of L ligand solution in
2
+
acetonitrile, at diꢂerent Ni concentrations. The arrow shows the
direction of absorbance changes by increasing the metal ion concen-
tration
very suitable and selective complexing reagent to recognize
2
+
Ni over the other metal ions in an analytical application
and separation processes. However, various factors exist that
need to be enhanced prior to use.
absorbance maximum are found by altering the [metal ion]/
[
triazene] mole ratio. Also, in all studied cases, the crea-
tion of a 1:1 complex in the solution is represented by such
an absorbance-mole ratio plots performance (Fig. 10). The
curve-ꢁtting program KINFIT [7, 12] was used to evaluate
the formation constant from the absorbance versus [metal
Analytical application
Another goal of this study was to assess the possibility of
using L (Scheme 1), as a chelating agent for the extraction
and preconcentration of Ni(II) in natural waters, under opti-
mum conditions. The eꢂects of various experimental factors
such as pH, nature of the organic solvent, salt eꢂect, period
of extraction, ligand concentration, and the volume ratio of
organic phase on the extraction yield were investigated, and
ion]/[triazene] mole ratio data. The results showed that logK
f
2
+
2+
of 5.60± 0.01 for Ni , 3.67± 0.01 for Co , 3.41± 0.02 for
2
+
+2
Pb , 3.29 ± 0.02 for Cd , and < 3 for other metal ions.
Hence, considering the selectivity orders gained from the
solution examinations, in the next step, L was used as a
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Journal of the Iranian Chemical Society
2
+
Fig. 11 Eꢂect of pH on the extraction percent of Ni using L. 10 ml
−
5
2+
of 1.0×10 M Ni in aqueous solution was extracted by 2 ml of
−
5
5
.0×10 M L as an extractant in chloroform
2
+
Ni was determined from 10 ml of the aqueous solution as
described in [13]. The metal ion concentration in the organic
phase was deꢁned by spectrophotometry.
2
+
Fig. 12 Absorption spectra for ligand L (curve 1), and its Ni com-
−
5
2+
plex (curve 2) in chloroform. Condition: 10 ml 0f 4.0×10 M Ni
in aqueous solution extracted by 2 ml of 4.0×10− M L in chloroform
5
The ꢁndings indicated that extracting the nickel ions was
complete in the pH range of 6.5–8.5 (Fig. 11). Therefore,
pH=7.5 was selected as the optimal pH for further works.
Greater pH values (>10) were not utilized due to the likeli-
hood of the Ni(II) hydroxide formation in solution.
The extraction time was studied in the time range of 30
to 210 s. The quantitative extraction of Ni(II) was obtained
in 120 s. Prolonged shaking did not have any considerable
impact on the target analyte extraction.
procedure is described in the following: A 10-ml aliquot
−
6
of an aqueous solution containing 8.0 × 10 M of Ni(II)
at pH=7.5 was transported to a separatory funnel. Adding
−
5
2
ml chloroform containing 4.0×10 M of L to funnel, it
was shaken for 2 min until reaching the desired mixture. The
two phases were permitted to relax and discrete completely.
Then, the yellow-colored organic phase was separated, and
its absorbance was measured at 421 nm versus a reagent
blank solution.
The suitability of several solvents such as carbon tetra-
chloride, chloroform, benzene, and hexane was assessed
2+
2
+
To assess the selective separation and determine Ni ions
from binary mixtures with various metal ions, an aliquot of
for the extraction of Ni ions from the aqueous phase. It
was indicated that chloroform could be used to extract the
complex of the metal ion. In other diluents, extraction was
incomplete. The other analytical data for the extraction were
investigated as reported in [10]. A list of the experimental
conditions in the liquid–liquid extraction is given in Table 4.
−5
solution (10 ml) was taken comprising 5.0×10 M of Ni(II)
ions and a varying amount of some other cations. As shown
2
+
in Table 5, Ni ions in the binary mixtures were extracted
almost completely and do not represent signiꢁcant interfer-
ing impacts at a 1:100 ratio.
As shown in Fig. 12, λ of the complex in the organic
max
The suggested technique was used for separating and
phase is 421 nm, while the L did not show a signiꢁcant
absorbance at this wavelength. Hence, 421 nm was chosen
for measuring the absorbance. The proposed extraction
2
+
determining Ni ions in some natural water samples. The
ꢁ
ndings of the analysis provided in Table 6 indicate a good
consistency within the values measured utilizing the sug-
gested technique and those reported with atomic absorp-
tion spectrometry (AAS) laboratory at Lorestan University,
Khorramabad, Iran. Overall, it can be concluded that the new
Table 4 Analytical characteristics of the liquid–liquid extraction for
determination of Ni(II) ions
2
+
Parameter
Analytical feature
triazene-1-oxide derivative L is selective to Ni and can be
utilized in the determination of this ion in real specimens.
Extraction time
120 s (at room temperature)
pH
7.5
5:1
0.5 M
1:5 ratio
6.0×10
9.2×10 –8.4×10
y=78750[Ni ]+0.014
2
+
Concentration ratio of L to Ni
The salt concentration
Ratio of organic to aqueous phase
Conclusion
X-ray spectroscopy was used to synthesize and characterize
the 1-(4-methylphenyl)-3-(2-(triꢀuoromethyl)phenyl)triaz-1-
ene 1-oxide (L). The compound L crystallizes in the space
−1
−7
Limit of detection (mol l
)
−
1
−7
−3
Linear range (mol l
)
Regression equation, [Ni2+] (mol.L−1
)
2+
group P2 /c of a monoclinic system with 4 molecules in
1
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3

Journal of the Iranian Chemical Society
Table 5 Eꢂect of various metal ions on the preconcentration and
University of Toronto, Chemistry Department, for his assistance and
support. I would also like to thank Pascal Retailleau, Service de Cristal-
lochimie, Cedex, France, for allowing the use of their X-ray facilities.
a
determination of Ni(II) ions with the recommended method
Interfering ion
Ratio interfering ions/
Recovery
2
+
2+
Ni
of Ni ions
Compliance with ethical standards
(
%)
+
Ag
200
200
200
100
150
100
200
100
200
200
150
200
200
200
300
300
98.2
98.3
98.6
97.2
96.5
97.2
98.5
97.6
96.7
97.6
97.9
96.9
98.1
98.0
98.9
98.4
Conflict of interest The authors state that they have no conꢀicts of in-
2
2
+
+
Ca
Ba
Cd
Cu
Co
Zn
Pb
terest.
2
2
2
+
+
+
+
References
2
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1
0. M.J. Frisch, G.W. Trucks, H.B. Schlegel, G.E. Scuseria, M.A.
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proposed method
AAS
2.63(± 0.24)×10−
6
6
6
−6
−6
−6
River water of kakareza
Spring water of Golestan
2.47×10
2.09×10
1.45×10
−
2.16(± 0.18)×10
Spring water of Tirebazar village 1.35(± 0.19)×10−
a
Values in the parentheses are % RSD based on the three replicate
analyses
the unit cell of dimensions a=8.066(2) Å, b=16.740(5) Å,
c=11.730(4) Å, α=90.00°, β=117.76°, and γ=90.00°. The
complexation studies of triazene-1-oxide derivative L with a
(
Gaussian Inc, Wallingford CT, 2009)
2+
+
2+
2+
2+
variety of metal ions including Ni , Ag , Pb , Mn , Hg ,
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SHELXL97 (University of Gottingen, Germany, 1997)
2
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2+
2+
Cd , Zn , Cu , and Co were carried out by a spectro-
photometry method in acetonitrile solution at room tempera-
ture. Therefore, based on the selectivity orders attained from
the solution studies, the ligand was successfully used as an
1
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1
2
+
extractant for the selective extraction of Ni ion over the
other metal ions in separation processes.
Acknowledgement It is my pleasure to express thanks to the Research
Council of Lorestan University for their support with the completion
of this research study. I wish to thank Prof. Datong Song from the
1
3