Synthesis, crystal structures and properties of two copper (II) complexes with pyridazine derivative ligand

Article abstract of DOI:10.1007/s10870-008-9390-2

Two new complexes, [Cu(L)₂(CH₃OH)]·(ClO ₄)₂ (1) and [Cu(L)₂(H₂O)] ·(NO₃)₂ (2), have been synthesized and their crystal structures have been determined by X-ray analysis, where L = 3-(3,5-bimethylpyrazole-yl)-6-chloro-pyridazine]. The complex 1 crystallizes in the monoclinic, space group C2/c, and the coordination configuration of copper (II) is better described as trigonal pyramidal geometry with four N atoms from L and one O _methanol ^. The coordination configuration of 2 is quite similar to that of 1 except O_water instead of O _methanol ^. The intermolecular hydrogen bonds link the repeat units and extend the molecules to multinuclear structures in both compounds. The spectral properties of the title compounds have been studied and discussed. Furthermore, the antibacterial activities of the title compounds have been detected, the results indicate that the ligands and two copper(II) complexes exhibit certain fungicidal activities again several bacteria.

Full text of DOI:10.1007/s10870-008-9390-2

J Chem Crystallogr (2008) 38:781–786
DOI 10.1007/s10870-008-9390-2
ORIGINAL PAPER
Synthesis, Crystal Structures and Properties of Two Copper (II)
Complexes with Pyridazine Derivative Ligand
Xiu-rong Li Æ Zhi-hui Zhang Æ Xiu-feng Liu Æ Hong Gao Æ Xiang-nan Zhang Æ
Zhi-jin Fan
Received: 11 July 2007 / Accepted: 2 April 2008 / Published online: 25 April 2008
Ó Springer Science+Business Media, LLC 2008
Abstract Two new complexes, [Cu(L)2(CH3OH)] ꢀ (ClO4)2
(1) and [Cu(L)2(H2O)] ꢀ (NO3)2 (2), have been synthesized
and their crystal structures have been determined by X-ray
analysis, where L = 3-(3,5-bimethylpyrazole-yl)-6-chloro-
pyridazine]. The complex 1 crystallizes in the monoclinic,
space group C2/c, and the coordination configuration of
copper (II) is better described as trigonal pyramidal geom-
etry with four N atoms from L and one O.methanol The
coordination configuration of 2 is quite similar to that of 1
except Owater instead of O.methanol The intermolecular
hydrogen bonds link the repeat units and extend the mole-
cules to multinuclear structures in both compounds. The
spectral properties of the title compounds have been studied
and discussed. Furthermore, the antibacterial activities of the
title compounds have been detected, the results indicate that
the ligands and two copper(II) complexes exhibit certain
fungicidal activities again several bacteria.
interaction of the counter ion with the solvent affects on the
coordinated configuration of the metal complexes. Pyrida-
zine and its derivatives are the important compounds in
synthesis of agricultural chemicals and medicines owing to
the biological activities of these compounds [2, 3]. However,
pyridazine derivatives are more difficult to prepare because
of the poor electron on the pyridazine ring, the substituted
group on 3 or 6 sites on pyridazine rings influents on the
reactivity of pyridazines [4–7]. Pyrazole derivatives bridg-
ing link more than two metal atoms in various coordination
models to form multi-nuclear coordination polymers.
Diversion pyrazole derivatives have been used in the coor-
dination chemistry and metal organic chemistry areas [8–
10]. In order to study the effect of the counter ion on the
molecular structure of the copper (II) complexes and to find
the new compounds with higher drug activity and simple
molecular structure, in this paper, a new ligand contained
pyridazine with substituted pyrazole groups and their two
copper (II) complexes with various counter ions have been
synthesized, and the properties of the title compounds have
been studied.
Keywords 3,5-Dimethylpyrazole ꢀ Pyridazine ꢀ
Copper(II) complex ꢀ Crystal structure ꢀ Fungicidal activity
Introduction
Experimental
The effect of the property of the counter ion on the molecular
structures of the metal complexes have been paid attention in
construction of crystal engineering [1]. The reasons are:
First, the coordination ability of the counter ion can change
the configurations of the complexes; second, the non-coor-
dinated bond provided by the counter ion can develop the
repeat units to higher-dimension structures; third, the
Materials and General Methods
All of the starting materials and solvents were commer-
cially purchased and purified by standard methods prior to
use. 3,5-bimethyl-pyrazole is synthesized by the literature
method [11]. IR spectra were recorded on a Bruker Vector
22 FT-IR spectrometer with KBr discs. Elemental analysis
(C, H, N) were carried out with a Perkin-Elmer 240 ana-
lyzer. Electronic spectra were recorded on Shimadzu
Uv-265 FW instrument.
X. Li ꢀ Z. Zhang (&) ꢀ X. Liu ꢀ H. Gao ꢀ X. Zhang ꢀ Z. Fan
The College of Chemistry, Nankai University,
Tianjin 300071, China
e-mail: zhangzh67@nankai.edu.cn
123

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J Chem Crystallogr (2008) 38:781–786
Synthesis of the Ligands
799(w). Anal. Calcd for C18H20Cl2CuN10O7: C, 34.71; H,
3.24; N, 22.49 %. Found: C, 34.67; H, 3.29; N, 22.46%.
The ligand (L) was synthesized referenced the literature
method [12]: Metal Na pieces (0.598 g, 0.026 mol) were
added carefully to the solution of 3,5-bimethyl-pyrazole
(2.5 g, 0.026 mol) in dry THF (75 mL) under N2 protect-
ing. The reaction mixture was stirring for 30 min, 3,6-
bichloropyridazine (3.87 g, 0.026 mol) was added to the
reaction mixture mentioned above. The reaction mixture
was refluxing for 4 h, it was filtered. The filtrate was re-
crystallized in methanol to isolate the L, yield: 68.6%.
Anal. Calcd for C9H9N4Cl (mol. Wt. 208.5): C, 51.81; H,
4.35; N, 26.85. Found: C, 51.76; H, 4.39; N, 26.80. IR.
(KBr pellets, cm-1): 3201 m, 3143(s), 3093(m), 3052(m),
2982(m), 2929(m), 1574(m), 1539(m), 1427(s), 1361(m),
1137(m), 1084(s), 972(m), 855(m), 790(m), 742(w),
507(w).
X-ray Crystallography
The crystals of two copper(II) complexes were mounted on
a glass fiber, respectively. Determination of the unit cell
and data collection were performed using MoKa radiation
´
(k = 0.71073 A) on a Bruker SMART 1000 diffractometer
equipped with a CCD camera. The x - 2h scan technique
was employed. The structures were solved primarily by
direct methods and secondly by Fourier difference tech-
niques and refined using the full-matrix least-squares
method. The computations were performed with the
SHELXS-97 and the SHELXL-97 programs [13]. All non-
hydrogen atoms were refined anisotropically. All the
hydrogen atoms were located on the calculated positions
and refined as riding atoms with a common fixed isotropic
thermal parameter. Crystal parameters and structure
refinements for the compounds are summarized in Table 1.
The molecular structure of the ligand L is shown as
Chart 1.
Synthesis of [Cu(L)2(CH3OH)] ꢀ (ClO4)2 (1)
Results and Discussion
A solution of Cu(ClO4)2 ꢀ 6H2O (0.37 g, 0.1 mmol) in
methanol (5 mL) was added dropwise to the methanol
solution (5 mL) of L (0.1 mmol), which was continuously
stirring for 30 min. The reaction mixture was filtered, and
the filtrate was kept to stand for over 3 weeks. The green
single crystals of 1 suitable for X-ray analysis were
obtained, yield: 60%. IR (KBr pellets, cm-1): 3453(br),
3118(w), 1584(m), 1482(m), 1425(s), 1276(w), 1075(s),
835(m), 799(m), 627(m), 523(w). Anal. Calcd for
C19H22Cl4CuN8O9: C, 32.06; H, 3.12; N, 15.74%. Found:
C, 32.01; H, 3.16; N, 15.70%.
Description of the Structures
[Cu(L)2(CH3OH)] ꢀ (ClO4)2 (1). The perspective view of 1
is given in Fig. 1. The selected bond lengths and angles are
summarized in Table 2.
From the Fig. 1, it can be seen that the coordination
configuration of the Cu(II) atom is best described a trigonal
bipyramidal configuration with the bond angles being N(1)–
Cu(1)–O(1) = 87.45°, N(1A)–Cu(1)–O(1) = 93.18°, N(3)–
Cu(1)–O(1) = 100.63° and N(3A)–Cu(1)–O(1) = 130.86°,
which has be tested by Addision s rule [14] (s = 0.9387
indicates the configuration is closed the idea trigonal bi-
pyramid). The mean plane is defined by O(1), N(3) and
N(3A), N(1) and N(1A) occupy the apical sites with the bond
angle N(1)–Cu(1)–N(1A) = 176.9°. The total bond angles
of N(3)–Cu(1)–N(3A) = 128.51°, N(3)–Cu(1)–O(1) =
100.63° and N(3A)–Cu(1)–O(1) = 130.86° is 360°, which is
shown that Cu(1) atom is in the mean plane. Two molecules
of 1 are linked by the weaker intermolecular action through
perchlorate ion in l-O,O model to present a binuclear
structure (Fig. 2). The data of the inter-molecular action is
summarized in Table 3.
Synthesis of [Cu(L)2(H2O)] ꢀ (NO3)2 (2)
Running the same procedure as that of 1, except
Cu(NO3)2 ꢀ 3H2O instead of Cu(ClO4)2 ꢀ 6H2O. The blue
green single crystals of 2 suitable for X-ray analysis were
isolated, yield: 42%. IR. (KBr pellets, cm-1): 3460(br),
3096(w), 1626(w), 1583(m), 1478(m), 1425(s), 1382(s),
1209(w), 1161(m), 1122(m), 1074(w), 997(m), 840(m),
[Cu(L)2(H2O)] ꢀ (NO3)2 (2). The molecular configura-
tion of 2 is quite similar to that of 1 except a H2O
coordinated instead of CH3OH coordinated (Fig. 3), and
the selected bond distances and angles are summarized in
Table 4. There is weaker interaction between 2 and NO3-
ion in the unit cell of 2 (Fig. 4). The Cu(L)2(H2O)2+ ions
are linked by the intermolecular hydrogen bond to form a
N
Cl
N
N
N
Chart 1 The molecular structure of L
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J Chem Crystallogr (2008) 38:781–786
783
˚
Table 1 Crystallographic data and structures refinements for Com-
plexes 1 and 2
Table 2 The bond length (A) and bond angle (°) of the complex 1
Bond lengths
Complex
1
2
Cu(1)–N(1)
Cu(1)–N(3)
Cu(1)–O(1)
1.957(3)
2.053(3)
2.155(5)
Cu(1)–N(1)a
Cu(1)–N(3)a
Cu(1)–O(1)a
1.957(3)
2.053(3)
2.155(5)
Empirical formula
Formula weight
Temperature (K)
C19H22Cl4CuN8O9
711.79
C18H20Cl2CuN10O7
626.88
294(2)
294(2)
Bond angles
System, space group Monoclinic, C2/c
Orthorhombic, Ccc2
´
a (A)
N(1)–Cu(1)–N(1)a 179.24(16) N(1)–Cu(1)–N(3)
N(1)a–Cu(1)–N(3) 100.73(10) N(1)–Cu(1)–N(3)a 100.73(10)
78.93(10)
2.4082(14)
7.672(4)
1.8261(10)
90
1.8041(3)
´
b (A)
2.1397(3)
´
c (A)
N(1)a–Cu(1)–N(3)a
N(1)–Cu(1)–O(1)a
78.93(10) N(3)–Cu(1)–N(3)a 128.51(15)
93.28(18) N(1)a–Cu(1)–O(1)a
87.45(18)
6.7417(11)
a (°)
90
N(3)–Cu(1)–O(1)a 130.86(18) N(3)a–Cu(1)–O(1)a 100.63(17)
b (°)
c (°)
V (nm3)
121.592(8)
90
90
87.45(18) N(1)a–Cu(1)–O(1)
100.63(17) N(3)a–Cu(1)–O(1) 130.86(17)
93.28(18)
90
N(1)–Cu(1)–O(1)
N(3)–Cu(1)–O(1)
O(1)a–Cu(1)–O(1)
2874 (3)
4
2602.4(7)
4
Z
30.2(3)
Crystal size (mm3)
Dcalcd (g cm-3
l (MoKa) mm-1
0.26 9 0.249 0.16 0.229 0.189 0.14
Symmetry transformations used to generate equivalent atoms: a -x, y,
-z + 1/2
)
1.645
1.590
1.193
1.103
F (000)
1444
1268
tetra-nuclear structure unit, and the tetra-nuclear structures
are extended further to 1D chain supermolecular structure
by the intermolecular action as shown in Fig. 5.
2h range (°)
Limiting indices
2.62–26.55
1.48–26.41
-12 B h B 30,
-9 B k B 9B,
-22 B l B 15
-22 B h B 22,
-19 B k B 26,
-7 B l B 8
In contrast 1 with 2, it is found that there is competition
coordination between H2O and CH3OH in the same system,
the coordinated ability of H2O and CH3OH might be arise
from the various affinity of the counter ions, ClO-4 and NO3-,
to H2O and CH3OH. In 1, methanol molecule coordinates
with the Cu (II) atom might be due to the larger affinity of
ClO-4 to H2O than that of ClO4- to CH3OH; while the larger
affinity of NO3 to CH3OH than that of NO-3 to H2O might
lead to a H2O molecule coordinates with Cu (II) in 2. It
reminds that the affinity of counter ions is one of the factors
of the controlling configuration of the complex.
Reflec. collect/uniqu 7863/2965
[R(int) = 0.0339]
1.030
2965/110/234
7202/2463
[R(int) = 0.0320]
GOF on F2
1.012
Data/restrs./params
2463/7/175
R1 and wR2 [I [ 2r(I)] R1 = 0.0425,
wR2 = 0.1105
R1 = 0.0346,
wR2 = 0.0827
R indices (all data)
R1 = 0.0670,
wR2 = 0.1256
R1 = 0.0500,
wR2 = 0.0900
Largest diff. Peak hole 0.483 and -0.441
-3
0.279 and -0.410
´
(e A
)
Fig. 1 ORTEP view of the
complex 1
123

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J Chem Crystallogr (2008) 38:781–786
Fig. 2 The pseudo binuclear
structure linked by the
intermolecular hydrogen bond
in 1
´
˚
Table 4 Selected bond distance (A) and bond angle (°) for 2
Table 3 The data of hydrogen bonds and the inter-molecular action
in the complex 1
Bond lengths
˚
˚
D–HꢀꢀꢀA
HꢀꢀꢀA (A)
DꢀꢀꢀA (A)
\D–HꢀꢀꢀA (°)
Cu(1)–N(1)
Cu(1)–O(1)
Cu(1)–N(3)
1.951(3)
1.993(6)
2.086(3)
Cu(1)–N(1A)
Cu(1)–N(3A)
1.951(3)
2.086(3)
C3AB–H3ABꢀꢀꢀO2Aa
C3AA–H3AAꢀꢀꢀO2Ba
O5AꢀꢀꢀO1Cb
2.545
2.545
3.354
3.354
2.563
2.563
b
145.7
145.7
Bond angles
O5BꢀꢀꢀO1Cb
N(1)–Cu(1)–N(1A)a
N(1A)–Cu(1)–O(1)
177.2(2) N(1)–Cu(1)–O(1)
91.42(11)
a
Symmetry codes: 0.5 + x, 1.5 - y, 0.5 + z; 0.5 - x, 0.5 + y,
0.5 - z
91.42(11) N(1)–Cu(1)–N(3A) 99.93(12)
N(1A)–Cu(1)–N(3A)a 78.63(11) O(1)–Cu(1)–N(3A) 119.56(8)
N(1)–Cu(1)–N(3)
O(1)–Cu(1)–N(3)
78.64(11) N(1A)–Cu(1)–N(3) 99.93(12)
119.56(8) N(3A)–Cu(1)–N(3) 120.88(17)
Symmetry transformations used to generate equivalent atoms:
a
-x + 2, y, -z + 1/2
The Spectra Properties of the Complexes
In IR spectra of 1, the vibration bands of the pyridazine
and pyrazole rings are at 1,574–1,360 cm-1, a stronger
broad peak for O–H bond of methanol at 3,453 cm-1. A
broad strong peak at 1075 cm-1 is the contribution of
ClO4. In the IR spectra of 2, there is doublet character
peaks at 1,425 and 1,382 cm-1 assigned to that of NO3
ion [15]. IR spectra are consistent with the results of
X-ray analysis.
The electronic spectra and assignments of the title
complexes are summarized in Table 5. The strong trans-
ferring bands in the ligand have been observed, while the
d–d bands of the metal complexes 1 and 2 have not
Fig. 3 ORTEP view of the complex 2
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J Chem Crystallogr (2008) 38:781–786
785
found, which might be due to it is covered by that of
ligands.
Biological Activity
The fungicidal activity of the ligand and the metal com-
plexes has been tested in vitro against Alternaria solani,
Gibberella zeae, Physalospora piricola, Phomaasparagi,
Cercospora arachidicola and their relative inhibitory ratio
(%) has been determined by using the mycelium growth
rate method [17]. After the mycelia grew completely, the
diameters of the mycelia have been measured and the
inhibition rate is calculated according to the formula:
D1 ꢁ D0
D1
I ¼
ꢂ 100%
In the formula, I is the inhibition rate, D1 is the average
diameter of mycelia in the blank test, and D0 is the average
diameter of mycelia in the presence of the compounds.
The inhibition ratio of the compounds at 50 lg/cm3 has
been determined, and the experimental results are sum-
marized in Table 6. The screening data indicate that L
exhibits certain activity against only Physalospora pirico-
la. Both complexes exhibit higher antibacterial activities
than that of the ligand, which might be owing to the bio-
logical activity of the copper(II) ion [18]. The activity of 2
is better than that of 1, the relationship of the activity with
the molecular structure is being studied.
Fig. 4 The weaker hydrogen bond action of adjacent molecules in 2
In summary, two copper(II) complexes, [Cu(L)2
(CH3OH)] ꢀ (ClO4)2 1 and [Cu(L)2(H2O)](NO3)2 2, have
been prepared and characterized. There are hydrogen bond
and weaker inter-molecular action to extend further the
discrete subunits to a pseudo dimmer in 1 and a tetra-
nuclear structure in 2, respectively. The spectra properties
of the copper(II) complexes have been studied. Moreover,
the antibacterial function of the title compounds has been
tested and the results indicate that copper complexes
exhibit higher activity than that of the ligand due to the
biological activity of the copper ion.
Fig. 5 The 1D chain linked by the intermolecular hydrogen bond in 2
Table 5 The electronic spectra of the title complexes
kmax (e/mol-1 dm3 cm-1
)
Assignment [16]
Supplementary Material
Compound
Complex 1
261 (18170)
211 (9200)
268 (14600)
LMCT
K?K
LMCT
The structures data have been deposited with the Cam-
bridge Crystallographic Data-base Center. CCDC677872
for 1 and CCDC 619411 for 2.
Complex 2
Table 6 Fungicidal activity of
the ligand and the title
complexes
Compound Relative
Gibberellaz
zeae
Inhibitory
Alternaria
solani
Ratio (%)a
Cercospora
arachidicola
Physalospora
piricola
Phoma
asparagi
L
1
2
0
0
0
0
0
39.7
47.1
47.1
0
0
0
0
12.5
25.0
a
The data is the average of
three tested results
23.5
123

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J Chem Crystallogr (2008) 38:781–786
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31:83; (b) Jonas RB (1989) Appl Environ Microbiol 55:43
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