Synthesis of metal complexes of 1-phenyl-3-methyl-4-benzoylpyrazole-5-one semicarbazone by solid-state and solution reactions

Article abstract of DOI:10.1081/SIM-200055235

1-Phenyl-3-methyl-4-benzoylpyrazole-5-one semicarbazone (HL) and its complexes have been prepared and characterized on the basis of elemental analyses, IR spectra, ¹H NMR spectra, mass spectra, molar conductivity, thermal analyses and X-ray powder diffraction. The spectral data show that the complexes obtained by solution reactions have the general formulas [ML₂]·nH₂O [M = Mn(II), Co(II), Ni(II), Zn(H)] in which the ligand chelates to the metal ion in a mononegative O,N,O-tridentate fashion. On the other hand, the complexes obtained by solid-state reactions have the formulas [M(HL)(OAc)₂]·nH₂O, in which the ligand acts as a neutral bidenate entity that coordinates through the carbonyl oxygen of the pyrazolone ring, the azomethine nitrogen and the two acetate groups that are monodenate. Copyright

Full text of DOI:10.1081/SIM-200055235

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Synthesis of Metal Complexes of
1‐Phenyl‐3‐methyl‐4‐benzoylpyrazole‐5‐one
Semicarbazone by Solid‐State and Solution Reactions
Lang Liu a & Dianzeng Jia a
a Institute of Applied Chemistry , Xinjiang University , Urumqi, China
Published online: 16 Aug 2006.
To cite this article: Lang Liu & Dianzeng Jia (2005) Synthesis of Metal Complexes of
1‐Phenyl‐3‐methyl‐4‐benzoylpyrazole‐5‐one Semicarbazone by Solid‐State and Solution Reactions, Synthesis and Reactivity in
Inorganic, Metal-Organic, and Nano-Metal Chemistry, 35:4, 269-274, DOI: 10.1081/SIM-200055235
To link to this article: http://dx.doi.org/10.1081/SIM-200055235
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Synthesis and Reactivity in Inorganic, Metal-Organic and Nano-Metal Chemistry, 35:269–274, 2005
Copyright # 2005 Taylor & Francis, Inc.
ISSN: 0094-5714 print/1532-2440 online
DOI: 10.1081/SIM-200055235
Synthesis of Metal Complexes of 1-Phenyl-3-methyl-4-
benzoylpyrazole-5-one Semicarbazone by Solid-State and
Solution Reactions
Lang Liu and Dianzeng Jia
Institute of Applied Chemistry, Xinjiang University, Urumqi, China
Similarly, biological activities of complexes derived from
1-Phenyl-3-methyl-4-benzoylpyrazole-5-one semicarbazone(HL) hydrazones have been widely studied because of antimalarial
and its complexes have been prepared and characterized on the
and antituberculosis activities (Hueso-Urena et al., 1998;
West et al., 1993). Now they also have been the subject of
basis of elemental analyses, IR spectra, 1H NMR spectra, mass
spectra, molar conductivity, thermal analyses and X-ray powder
diffraction. The spectral data show that the complexes obtained
many researcher (Iskander and El-Sayed, 1976; Iskander and
El-Aggan, 1975), but few studies of pyrazolone semicarbazone
.
by solution reactions have the general formulas [ML2] nH2O
[M 5 Mn(II), Co(II), Ni(II), Zn(II)] in which the ligand chelates and its complexes, particularly its solid-state complexes, have
to the metal ion in a mononegative O,N,O-tridentate fashion. On
the other hand, the complexes obtained by solid-state reactions
.
have the formulas [M(HL)(OAc)2] nH2O, in which the ligand
acts as a neutral bidenate entity that coordinates through the
carbonyl oxygen of the pyrazolone ring, the azomethine nitrogen
and the two acetate groups that are monodenate.
been reported. In order to understand the coordination behavior
of a novel semicarbazone towards bivalent transition metal
ions under different reaction conditions, several metal com-
plexes of 1-phenyl-3-methyl-4-benzoylpyrazole-5-one semi-
carbazone (HL) (Figure 1) have been synthesized by
solid-state and solution reactions and characterized by ele-
1
mental analyses, IR spectra, H NMR spectra, mass spectra,
molar conductance, TG-DTA and X-ray powder diffraction.
Keywords complex, pyrazolone, semicarbazone, solid–state reaction
EXPERIMENTAL
INTRODUCTION
Physical Measurements and Materials
Much effort has been expanded recently to study pyrazolone
thiosemicarbazones because these compounds have photochro-
mic properties (Liu et al., 2002; Tang et al., 2000). According
to the analyses of their crystal structures, an intermolecular
proton transfer mechanism has been proposed. In order to
further confirm this mechanism and establish a relationship
between the photochromic properties and the structures, a
series of these derivates have been studied (Liu et al., 2002a,
2002b; Liu et al., 2001). There has been considerable interest
in metal complexes of 4-acylpyrazolones due to their
remarkable antitumor, antibacterial and antiviral activities
(Bukowsky et al., 1992; Mahalakshmi et al., 1998; Mirza,
1978; Radhakrishnan et al., 1998; Umatani et al., 1980).
Elemental analyses of carbon, hydrogen and nitrogen were
carried out with a model 2400 Perkin-Elmer analyzer.
Infrared spectra were measured on a Bio-RAD FTS-40 spectro-
photometer on KBr pellets. The molar conductance values
were determined in DMF with a model DSS-11A conductivity
meter. TG-DTA measurements were carried out on a Netzsch
1
STA 449C thermal analyzer. The H NMR spectrum of HL
was recorded on an AC-80 NMR spectrometer using CDC13
as solvent and TMS as an internal standard. Mass spectra
were obtained on a HP-5988GC/MS spectrometer. X-ray
powder diffraction studies were performed on a MAC
Science MXP18AHF diffractometer with Cu Ka radiation
˚
(l ¼ 1.054056 A). All chemicals and solvents used were
analytical grade reagents.
Received 12 May 2004; accepted 13 January 2005.
The authors are grateful to the National Natural Sciences Foun-
dation of China (No. 20262005) for financial support.
Address correspondence to Dianzeng Jia, Institute of Applied
Chemistry, Xinjiang University, Urumqi 830046, China. E-mail:
jdz@xju.edu.cn
Synthesis of HL
A methanol solution (100 mL) containing 1-phenyl-3-
methyl-4-benzoyl pyrazole-5-one (2.78 g, 10 mmol) and semi-
carbazide (0.75 g, 10 mmol) was boiled with stirring at reflux
269

270
L. LIU AND D. JIA
20.73%. 1H NMR (CDC13, d): 1.54 (s, 3H, CH3), 2.09
(s, 1H, CH), 5.09 (s, 1H, NH), 7.25–7.64 (m, 10H, 2C6H5),
7.93 (s, 2H, NH2). MS: [M þ 1]þ ¼ 336.
Preparation of Metal Complexes
Solution Reaction
A 2 mmol quantity of metal acetate was dissolved in water
(10 mL) and warmed to 508C. Each of the salt solutions was
added to a warm ethanol solution (100 mL) of HL (0.67 g,
2.0 mmol) with stirring. The mixture was heated under reflux
for 0.5 h and then cooled to room temperature. The resulting
product was recrystallized from the mixture of DMF/ethanol
(l : 4). The precipitate formed was filtered and washed with
ethanol, dried in air and stored in a desiccator.
FIG. 1. Structure of the ligand (HL).
Solid State Reaction
temperature for ca. 3 h. The resulting solution was concen-
trated to ca. 30 mL, and then cooled to room temperature.
HL (0.6707 g, 2.0 mmol) and the metal acetate [0.4899 g of
.
.
From the light yellow solution, a large amount of yellow Mn(OAc)2 4H2O; 0.4982 g of Co(OAc)2 4H2O; 0.4977 g of
.
.
solid powder was precipitated. The product was purified by Ni(OAc)2 4H2O; 0.4390 g of Zn(OAc)2 2H2O] in the mole
recrystallizing in anhydrous ethanol. Yield, 2.5 g (74.5%); ratio of 1 : 1 were mixed in an agate mortar in order to get
m.p. 190.0–191.08C. Anal. calcd. for C18H17N5O2 (335.37): the best possible homogeneity. The color of the reactants
C, 64.47; H, 5.11; N, 20.88%; found: C, 64.50; H, 5.12; N, changed immediately with strong acetic acid odors being
TABLE 1
Elemental analyses and molar conductivity of the compoundsa
Elemental analyses (%)
found (calcd.)
Yield
(%)
M.p. or
D.p. (8C)
LM
2
21
V21 cm mol
.
.
Formula
Method
L
F.W.
Color
C
H
N
HL
C18H17N5O2
.
[MnL2] H2O
C36H34MnN10O5
.
[CoL2] H2O
C36H34CoN10O5
.
[NiL2] 2H2O
C36H36N10NiO6
335.37 Yellow
741.67 Cream
745.66 Pink
64.50
(64.47)
58.59
5.12
(5.11)
4.47
20.73
(20.88)
19.01
84
85
82
80
80
94
190.0–191.0
.253.0
—
L
L
L
L
S
3.82
3.94
4.20
3.48
12.96
(58.30)
58.19
(4.62)
4.63
(18.89)
18.83
.257.0
(57.99)
56.32
(4.60)
4.73
(18.78)
17.96
763.44 Reseda
770.13 Pink
.307.0
(56.64)
56.14
(4.75)
4.69
(18.35)
17.97
.
[ZnL2] 2H2O
.237.0
C36H36N10O6Zn
[Mn(HL)(OAc)2]
3H2O
(56.15)
46.87
(46.96)
(4.71)
5.10
(5.20)
(18.19)
12.39
(12.45)
.
562.44 Cream
.141.0
C22H29MnN5O9
[Co(HL)(OAc)2]
3H2O
.
S
S
S
576.51 Pink
566.19 Green
518.83 Buff
46.46
(46.56)
4.91
(5.16)
12.23
(12.37)
95
95
96
.143.0
.146.0
.260.0
12.45
11.01
4.62
C22H29CoN5O9
[Ni(HL)(OAc)2]
3H2O
.
46.66
(46.67)
5.02
(5.16)
12.40
(12.37)
C22H29N5Ni5O9
[Zn(HL)(OAc)2]
C22H23N5O6Zn
50.97
(50.92)
4.37
(4.47)
13.54
(13.50)
aL: liquid state; S: Solid state.

TABLE 2
Major IR bands of HL and its complexes (cm21
)
Compound
HL
Method
n(OH)
n(NH2)
n(NH)
n(C55O)a n(C55O)b
n(C55N)
n(C55O)
nas(COO)
ns(COO)
n(M–O) n(M–N)
L
L
S
—
3654 m
3481 m
3363 m 3143 m
3357 m
3337 m 3157 m
1718 s
—
1717 s
1686 s
1653 s
1678 s
1626 s
1602 s
1592 s
—
1359 s
—
—
—
—
—
—
436 w
449 w
—
412 w
420 w
.
[MnL2] H2O
—
.
[Mn(HL)(OAc)2]
3H2O
1553 s
1329 s
.
[CoL2] H2O
L
S
3631 m
3477 m
3286 m —
3336 m 3149 m
—
1717 s
1652 s
1676 s
1600 s
1590 s
1364 m
—
—
1553 s
—
1329 s
431 w
447 w
416 w
428 w
.
[Co(HL)(OAc)2]
3H2O
.
[NiL2] 2H2O
L
S
3658 m
3475 m
3298 m —
3362 m 3146 m
—
1718 s
1651 s
1685 s
1603 s
1624 s
1364 m
—
—
1591 s
—
1372 s
443 w
450 w
412 w
428 w
.
[Ni(HL)(OAc)2]
3H2O
.
[ZnL2] 2H2O
[Zn(HL)(OAc)2]
L
S
3600 m
—
3287 m —
3357 m 3180 m
—
1718 s
1658 s
1665 s
1603 s
1603 s
1363 m
—
—
1552 s
—
1368 s
440 w
455 w
415 w
432 w
an(C¼O) of hydrazide moiety.
bn(C¼O) of pyrazolone moiety.

272
L. LIU AND D. JIA
discharged. The mixture was ground for 1 h and heated on a as a mononegative tridentate ligand forming two conjugated
water bath at 708C for 3 h to accelerate the reaction. After chelate rings and existing in the enolized form in the
further ground at room temperature, the product was dried in complexes.
a desiccator. It is noticed that the solid-state products should
not be washed by water, ethanol, etc.
The Solid-State Complexes
IR spectral data of the solid-state complexes show that HL
RESULTS AND DISCUSSION
acts as a neutral bidenate ligand coordinating through the
carbonyl oxygen atom of the pyrazolone ring and the azo-
methine nitrogen atom forming a six-membered. This mode
of chelation is supported by the following evidence. (1) The
v(C55N) band shifts to lower wave number. (2) The v(C55O)
of pyrazolone moiety band also shifts to lower wave number.
(3) The v(C55O) of hydrazide moiety bands remain more or
less at the same position, suggesting non-coordination of the
carbonyl oxygen of semicarbazide.
A summary of the analytical results and some physical pro-
perties of HL and its complexes are shown in Table 1. The data
obtained show that HL forms 1 : 2 complexes by the solution
reaction and 1 : 1 complexes by the solid-state reaction.
The products are in good agreement with the formulas
.
[ML2] nH2O (M ¼ Mn, Co, n ¼ 1; M ¼ Ni, Zn, n ¼ 2) and
.
[M(HL)(OAc)2] nH2O (M ¼ Mn, Co, Ni, n ¼ 3; M ¼ Zn,
n ¼ 0), respectively. The complexes are colored, air-stable
solids. They are slightly soluble in DMF and DMSO. The
molar conductivities of the complexes are around
The bands in the region of the 1552–1591 and 1329–
1372 cm21 are attributed to vas and vsy frequencies of OAc2,
respectively. The frequency difference between these two
bands indicates monodentate coordination of the acetato
group (Nakagawa and Shimanouchi, 1964).
The new bands above 3477 cm21 in the all complexes,
except for [Zn(HL)(OAc)2], are assigned to the O–H stretching
vibration, which indicates that water molecules are involved in
these complexes. This is in agreement with the results of the
elemental analyses. In the far-IR region two new bands at
431–455 and 412–436 cm21 in the complexes are assigned
to v(M–O) and v(M–N), respectively (EI-Tabl et al., 2002;
Liu et al., 2002a).
2
21
3.48 ꢀ 12.96 V2l cm mol in DMF, which shows that all
complexes are non-electrolytes in DMF (Geary, 1971). It is
emphasized that the solid-state products washed with water
or ethanol turn into the liquid-state complexes. In order to
confirm the conclusion mentioned above, the following experi-
ment was carried out. The solid-state Ni (II) complex was
washed with the water/ethanol or suspended in a small
amount of ethanol, refluxed for 0.5 h and filtered. The elemen-
tal analyses data of the product are C, 57.69; H, 4.59; N,
18.44%, which is consistent with the calculative values
.
.
.
(C, 58.01; H, 4.60; N, 18.79%) of NiL2 H2O. Thus, the com-
.
plex [Ni(HL)(OAc)2] 3H2O was transformed into the product
.
[NiL2] H2O, formed by the solution reaction. Moreover, the
XRD Analysis
Figure 2 shows X-ray diffraction patterns of the reaction
.
system of Zn(OAc)2 4H2O with HL. Obviously, the diffrac-
tion peaks of the starting materials disappear and new peaks
other solid-state complexes show similar phenomena. These
results suggest that the solid-state products are not only
unstable in solution, but also cannot be synthesized by
solution reactions. They are the intermediates of the solution
reaction (Chen et al., 1997; Lei and Xin, 1995; Yao et al.,
1995).
Infrared Spectra
The Liquid-State Complexes
The important infrared spectral frequencies are given in
Table 2. The v(C55N) band of HL at 1626 cm21 exhibits a
bathochromic shift of 23–26 cm21 for the complexes, which
suggests coordination of the azomethine nitrogen. The band
at 1718 cm2l for v(C55O) of hyrazide moiety and the band at
3143 cm21 for v(NH) in HL are absent in the complexes and
new absorption bands attributed to v(C–O2) (Niu et al.,
1998) are observed at 1359–1364 cm21. These imply that the
semicarbazide undergoes isomerization from the keto form to
the enol form during the solution reaction, and then coordinates
through a deprotonated oxygen. The shift of v(C55O) of
pyrazolone moiety to lower wave numbers shows that the
carbonyl oxygen atom of the pyrazolone ring bonds to the
FIG. 2. XRD patterns of Zn(II) complexes prepared by the solid-state and the
.
solution-state methods, respectively: (A) HL, (B) Zn(OAc)2 4H2O, (C)
.
metal ion. All of these data confirm the fact that HL behaves [Zn(HL)(OAc)2], and (D) [ZnL2] 2H2O.

SYNTHESIS OF METAL COMPLEXES BY REACTIONS
273
TABLE 3
Thermal analysis data of the complexes
Mass loss (%)
Found Calcd.
Solid
Decomposition
product
Decomposition
stage
Decomposition
range (8C)
Complex
Method
L
.
[MnL2] H2O
1
2
1
2
3
1
2
1
2
3
1
2
1
2
3
1
2
1
2
70–253
253–750
54–141
141–228
228–689
50–257
257–800
50–143
143–229
229–564
80–327
327–686
54–146
146–307
307–560
60–237
237–800
60–352
352–566
2.03
87.72
8.48
2.43
88.01
9.61
MnL2
MnO
Mn(HL) (OAc)2
.
[Mn(HL)(OAc)2] 3H2O
.
S
.
Mn(HL) (OAc)
10.89
67.37
2.39
10.50
67.28
2.42
MnO
CoL2
Co2O3
.
[CoL2] H2O
L
S
85.74
8.29
86.46
9.54
.
[Co(HL)(OAc)2] 3H2O
.
Co(HL) (OAc)2
.
Co(HL) (OAc)
10.89
61.95
20.57
67.71
9.27
10.42
61.51
19.92
69.15
9.55
CoNO2
NiL2
Ni2O3
.
[NiL2] 2H2O
L
S
.
[Ni(HL)(OAc)2] 3H2O
.
Ni(HL) (OAc)2
.
Ni(HL) (OAc)
21.37
53.61
4.43
20.86
54.99
4.68
Ni2O3
ZnL2
ZnO
.
[ZnL2] 2H2O
L
S
83.27
22.25
60.93
84.75
22.76
61.55
[Zn(HL)(OAc)2]
Zn(HL)
ZnO
of the product appear in the X-ray diffraction patterns. This Thermal Decomposition Studies
reveals that the solid-state product is a new species and not
the mechanical mixture of the reactants. The XRD patterns C
and D in Figure 2 indicate that the solid-state product is differ-
ent from the liquid-state product. However, the X-ray diffrac-
tion pattern of C is quite broad. This is ascribed to the fact
that the solid-state product is not fully crystallized.
The thermal analysis data of the complexes are summarized
in Table 3. All complexes prepared in solution follow a two-
.
step decomposition. The first step, except for [NiL2] 2H2O,
is consistent with the loss of the water molecules in the temp-
erature range of 50–2578C. The second step occurs in a wide
temperature range and corresponds to decomposition of ML2,
FIG. 3. Suggested structure of the complexes prepared in solution FIG. 4. Suggested structure of the complexes prepared in solid-state
[M ¼ Mn(II), Co(II), Ni(II), Zn(II)].
[M ¼ Mn(II), Co(II), Ni(II), Zn(II)].

274
L. LIU AND D. JIA
0
.
Lei, L. X.; Xin, X. Q. Stepwise reaction of CuC12 2H2O with 2,2 -
bipyridyl in the solid state. J. Solid State Chem. 1995, 119,
299–303.
leading to the formation of the oxide, MxOy. All complexes
prepared in the solid state, except for [Zn(HL)(OAc)2],
follow a three-step decomposition. In the first step, the loss
of water molecules takes place in the temperature range of
50–1468C and is attributed to crystal water. In the second
stage, the loss of OAc2 occurs, while in the third stage, the
coordinated oxygen and nitrogen atoms of the Co(II)
complex remain bound to the metal ion. The final decompo-
sition product is CoNO2 (EI-Sayed et al., 2001). All decompo-
sition products of the other complexes prepared in the
solid-state are the corresponding oxides.
Liu, L.; Jia, D. Z.; Yu, K. B. Synthesis and crystal structure of the deri-
vants of hydrazide containing pyrazolone. Acta Chim. Sin. 59,
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Liu, L.; Jia, D. Z.; Yu, K. B. Synthesis, crystal structure and
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On the basis of the elemental analyses, spectral and thermal
analysis studies, we tentatively propose six-coordinate
geometry for the complexes prepared in solution, as shown
in Figure 3, and four-coordinate geometry for the complexes
prepared in the solid-state, as shown in Figure 4.
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