Construction of six non-covalent-bonded supramolecules from reactions of cadmium(II), and zinc(II) with 3,5-dimethylpyrazole and carboxylate ligands

Article abstract of DOI:10.1016/j.ica.2014.02.027

Six new complexes Cd(Hdmpz)₂(L1)₂ (1) (Hdmpz = 3,5-dimethylpyrazole, L1 = nicotinate), Zn(Hdmpz)₂(L2)₂ (2) (L2 = N-phenylanthranilate), Zn(Hdmpz)₂(L3)₂ (3) (L3 = N-phenylmaleamate), Cd(Hdmp

Full text of DOI:10.1016/j.ica.2014.02.027

Inorganica Chimica Acta 415 (2014) 31–43
Contents lists available at ScienceDirect
Inorganica Chimica Acta
journal homepage: www.elsevier.com/locate/ica
Construction of six non-covalent-bonded supramolecules from reactions
of cadmium(II), and zinc(II) with 3,5-dimethylpyrazole and carboxylate
ligands
b
Shouwen Jin a, , Daqi Wang
⇑
a Tianmu College ZheJiang A & F University, Lin’An 311300, PR China
b Department of Chemistry, Liaocheng University, Liaocheng 252059, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 3 May 2012
Received in revised form 22 February 2014
Accepted 24 February 2014
Available online 5 March 2014
Six new complexes Cd(Hdmpz)2(L1)2 (1) (Hdmpz = 3,5-dimethylpyrazole, L1 = nicotinate), Zn(Hdmpz)2
(L2)2 (2) (L2 = N-phenylanthranilate), Zn(Hdmpz)2(L3)2 (3) (L3 = N-phenylmaleamate), Cd(Hdmpz)4(L4)2
(4) (L4 = 5-chlorosalicylate), Cd2(Hdmpz)6(L5)2Cd(Hdmpz)4(HL5)2Á2H2O (5) (HL5 = hydrogen 1,4-
cyclohexanedicarboxylate, L5 = 1,4-cyclohexanedicarboxylate), and Zn(Hdmpz)2(L6) (6) (L6 = sebacate)
were prepared and characterized by elemental analysis, IR spectra, TG, and single crystal X-ray diffraction
analysis. The X-ray studies revealed that these complexes display mononuclear to trinuclear structures
with tetrahedral geometry around each zinc center, and octahedral geometry around each cadmium
ion. The Hdmpzs in all compounds are coordinated only in monodentate fashion with its neutral N group.
In all of the complexes except 5, all carboxylate groups behave as monodentate ligands. The uncoordi-
nated O atom of the carboxylate group in 1, 2, 4, 5, and 6, forms intramolecular hydrogen bond with
the N–H group of the Hdmpz. On the basis of X-ray crystallographic study the rich intra- and intermolec-
ular non-covalent interactions such as classical hydrogen bonds, ClÁ Á ÁO, C–HÁ Á ÁO, CH2Á Á ÁO, CH3Á Á ÁO, C–
Keywords:
Crystal structure
Supramolecules
3,5-Dimethylpyrazole
Carboxylate
Non-covalent interactions
HÁ Á Á
p, CH3–p, and p–p interactions are analyzed. The extensive nonbonding interactions in these com-
pounds are responsible for different structures such as 3D network, 2D sheet, and 3D layer network
structure.
Ó 2014 Elsevier B.V. All rights reserved.
1. Introduction
[4,5], but also in biologic activities [6,7] and physiological effects
[8,9]. A versatile carboxylate anions can adopt a wide range of
The design and synthesis of metal–organic framework
structures have received enormous attention [1] in recent years
due to their potential applications in diverse areas such as magne-
tism, catalysis, optical, and sorption properties [2,3]. The frame-
work structure of the coordination polymers is primarily
dependent upon the coordination preferences of the central metal
ions and the functionality of the ligands. Aside from the coordina-
bonding modes, including monodentate, symmetric and asymmet-
ric chelating, and bidentate and monodentate bridging [10].
Pyrazole or pyrazole derivative has been widely employed in
polypyrazolylborates to stabilize a variety of organometallic and
coordination compounds [11,12]. Up to now, a variety of complexes
containing 3,5-dimethylpyrazole (Hdmpz) have been synthesized
and employed in coordination chemistry or organometallic chemis-
try [13–15]. Many complexes with simple pyrazole both in terminal
as well as in bridging mode are also available [16–18]. But the com-
plexes in the presence of carboxylic acids and pyrazole derivatives
are not very common except some recently reported examples in
the literatures [19]. We have been working with coordination com-
pounds with mixed ligands of carboxylate and 3,5-dimethylpyra-
zole [20]. The pyrazole ligand and the carboxylate ligand appear
to possess similar steric requirements and, to a certain extent, also
similar bonding capabilities. In order to know the influence of the
carboxylate residue in the formation of new coordination polymers
and the role the weak non-covalent interactions played in forming
tion bonding interactions, the hydrogen bonding and p–p stacking
interactions, the solvent molecules, counterions and the ratio of
metal salt to organic ligand also influence the formation of the ulti-
mate architectures.
The research on the metal carboxylates has always been
intriguing in that they play important roles not only in synthetic
chemistry with the essence of labile coordination modes of carbox-
ylate group, such as architecture of open and porous framework
⇑
Corresponding author. Tel./fax: +86 571 6374 6755.
E-mail address: jinsw@zafu.edu.cn (S. Jin).
http://dx.doi.org/10.1016/j.ica.2014.02.027
0020-1693/Ó 2014 Elsevier B.V. All rights reserved.

32
S. Jin, D. Wang / Inorganica Chimica Acta 415 (2014) 31–43
the final supramolecular frameworks, we select the carboxylic acids
bearing the NH, CONH, OH and Cl units which are good groups in
forming hydrogen bonds [21]. Thus, in the following, we report
the synthesis, structural characterization and thermal behaviour
of Zn and Cd complexes via combination of 3,5-dimethylpyrazole
(Hdmpz) and different carboxylate ligands (Scheme 1), namely
2.2.2. Synthesis of Zn(Hdmpz)2(L2)2 (2)
A solution of Zn(CH3COO)2Á2H2O (0.022 g, 0.10 mmol) in 5 mL
of EtOH was added to a MeOH solution (12 mL) containing Hdmpz
(0.019 g, 0.20 mmol) and N-phenylanthranilic acid (HL2) (0.085 g,
0.40 mmol), under continuous stirring. The solution was stirred
for about 2 h at room temperature, the solution became turbid,
then a few drops of conc. ammonia was added till the solution be-
came clear completely. The clear solution was filtered into the test
tube, after several days colorless crystals formed, which was fil-
tered off, washed with EtOH and dried under vacuum to afford
0.10 g of the product. Yield: 76% (Based on Hdmpz). Elemental
analysis performed on crystals exposed to the atmosphere: Anal.
Calc. for C36H36N6O4Zn (682.08): C, 63.33; H, 5.27; N, 12.31. Found:
C, 63.27; H, 5.22; N, 12.23%. Infrared spectrum (KBr disc, cmÀ1):
3462br, 3333m, 3143m, 3065m, 2990m, 2969w, 2872m,
Cd(Hdmpz)2(L1)2
(1)
(Hdmpz = 3,5-dimethylpyrazole,
L1 =
nicotinate), Zn(Hdmpz)2(L2)2 (2) (L2 = N-phenylanthranilate),
Zn(Hdmpz)2(L3)2 (3) (L3 = N-phenylmaleamate), Cd(Hdmpz)4(L4)2
(4) (L4 = 5-chlorosalicylate), Cd2(Hdmpz)6(L5)2Cd(Hdmpz)4(HL5)2Á
2H2O (5) (HL5 = hydrogen 1,4-cyclohexanedicarboxylate), and
Zn(Hdmpz)2(L6) (6) (L6 = sebacate).
2. Experimental
1627s(mas(COO)), 1596m, 1525m, 1464m, 1422s(ms(COO)), 1381m,
1289m, 1245m, 1169m, 1102m, 1064m, 952m, 887m, 832m,
2.1. Materials and physical measurements
789m, 744m, 683m, 647m, 609m.
The chemicals and solvents used in this work were of analytical
grade and available commercially and were used without further
purification. The FT-IR spectra were recorded from KBr pellets in
range 4000–400 cmÀ1 on a Mattson Alpha-Centauri spectrometer.
Microanalytical (C, H, N) data were obtained with a Perkin-Elmer
Model 2400II elemental analyzer. Thermogravimetric analyses
(TGA) were studied by a Delta Series TA-SDT Q600 in a N2 atmo-
sphere between room temperature and 800 °C (heating rate
10 °C minÀ1) using Al crucibles.
2.2.3. Synthesis of Zn(Hdmpz)2(L3)2 (3)
A solution of Zn(CH3COO)2Á2H2O (0.022 g, 0.10 mmol) in 5 mL
of EtOH was added to an EtOH solution (6 mL) containing Hdmpz
(0.019 g, 0.20 mmol) and N-phenylmaleamic acid (HL3) (0.076 g,
0.40 mmol), under continuous stirring. The solution was stirred
for about 2 h at room temperature, the solution became turbid,
then a few drops of conc. ammonia was added till the solution be-
came clear completely. The clear solution was filtered into the test
tube, after several days colorless crystals formed, which was fil-
tered off, washed with EtOH and dried under vacuum to afford
0.092 g of the product. Yield: 72% (Based on Hdmpz). Elemental
analysis performed on crystals exposed to the atmosphere: Anal.
Calc. for C30H32N6O6Zn (637.99): C, 56.43; H, 5.01; N, 13.16. Found:
C, 56.36; H, 4.92; N, 13.11%. Infrared spectrum (KBr disc, cmÀ1):
3414w, 3283m, 3072m, 2985m, 2865m, 1660s(C@O), 1623m,
2.2. Synthesis of complexes
2.2.1. Synthesis of Cd(Hdmpz)2(L1)2 (1)
A solution of Cd(CH3COO)2Á2H2O (0.027 g, 0.10 mmol) in 6 mL
of MeOH was added to a MeOH solution (10 mL) containing Hdmpz
(0.019 g, 0.20 mmol) and nicotinic acid (HL1) (0.049 g, 0.40 mmol),
under continuous stirring. The solution was stirred for about 2 h at
room temperature, a small amount of precipitate formed, then a
few drops of conc. ammonia was added till the precipitate dis-
solved completely. The clear solution was filtered into a test tube,
after several days colorless block crystals formed, which was fil-
tered off, washed with MeOH and dried under vacuum to afford
0.082 g of the product. Yield: 75% (Based on Hdmpz). Elemental
analysis performed on crystals exposed to the atmosphere: Anal.
Calc. for C22H24CdN6O4 (548.87): C, 48.09; H, 4.37; N, 15.30. Found:
C, 48.02; H, 4.33; N, 15.22%. Infrared spectrum (KBr disc, cmÀ1):
1596s(mas(COO)), 1497m, 1449m, 1398s(ms(COO)), 1326m, 1279m,
1237m, 1176m, 1079m, 1021m, 967m, 882m, 804m, 762m,
721m, 674m, 617m.
2.2.4. Synthesis of Cd(Hdmpz)4(L4)2 (4)
A solution of Cd(CH3COO)2Á2H2O (0.027 g, 0.10 mmol) in 6 mL
of MeOH was added to an EtOH solution (4 mL) containing Hdmpz
(0.019 g, 0.20 mmol) and 5-chlorosalicylic acid (HL4) (0.069 g,
0.40 mmol), under continuous stirring. The solution was stirred
for about 2 h at room temperature, the solution became turbid,
then a few drops of conc. ammonia was added till the solution be-
came clear completely. The clear solution was filtered into the test
tube, after several days colorless crystals formed, which was
3444w(
m
as(NH)), 3288w(
m
s(NH)), 3132m, 3035m, 2945m, 2868m,
s(COO)),
1614s(
m
as(COO)), 1590m, 1565m, 1508m, 1458m, 1419s(
m
1389m, 1296m, 1228s, 1191m, 1050m, 1016m, 967m, 861m,
804m, 755m, 699m, 645m, 617m.
HO
H
OH
N
O
O
HN
O
OH
O
HO
HO
O
O
N
Cl
HL4
HL3
HL2
HL1
OH
O
O
O
N
NH
HO
HO
OH
Hdmpz
H2L5
H2L6
Scheme 1. The ligands used in this paper.

S. Jin, D. Wang / Inorganica Chimica Acta 415 (2014) 31–43
33
filtered off, washed with EtOH and dried under vacuum to afford
0.062 g of the product. Yield: 74% (Based on Cd(CH3COO)2Á2H2O).
Elemental analysis performed on crystals exposed to the atmo-
days colorless block crystals formed, which was filtered off,
washed with MeOH and dried under vacuum to afford 0.026 g of
the product. Yield: 57% (Based on Hdmpz). Elemental analysis
performed on crystals exposed to the atmosphere: Anal. Calc. for
sphere: Anal. Calc. for
C34H40CdCl2N8O6 (840.04): C, 48.57;
H, 4.76; N, 13.33. Found: C, 48.52; H, 4.69; N, 13.26%. Infrared spec-
C
20H32N4O4Zn (457.87): C, 52.42; H, 6.98; N, 12.23. Found: C,
52.37; H, 6.91; N, 12.13%. Infrared spectrum (KBr disc, cmÀ1):
3394m, 3242w, 3116m, 3062m, 2926m, 2851m, 1610s(
as(COOÀ)),
1570m, 1509m, 1451m, 1409s(
s(COOÀ)), 1382m, 1305m, 1281m,
trum (KBr disc, cmÀ1): 3546m, 3425w, 3268m, 3085m, 2928m,
2865m, 1611s(
m
as(COO)), 1557m, 1402s(
m
s(COO)), 1337m, 1269m,
m
1201m, 1176m, 1059m, 986m, 907m, 828m, 768m, 714m, 667m,
605m.
m
1243m, 1184m, 1017m, 935m, 879m, 823m, 742m, 653m, 607m.
2.3. X-ray crystallography
2.2.5. Synthesis of Cd2(Hdmpz)6(L5)2Cd(Hdmpz)4(HL5)2Á2H2O (5)
A solution of Cd(CH3COO)2Á2H2O (0.027 g, 0.10 mmol) in 6 mL
of MeOH was added to a MeOH solution (7 mL) containing Hdmpz
(0.019 g, 0.20 mmol) and 1,4-cyclohexanedicarboxylic acid (H2L5)
(0.034 g, 0.20 mmol), under continuous stirring. The solution was
stirred for about 2 h at room temperature, the solution became tur-
bid, then a few drops of conc. ammonia was added till the solution
became clear completely. The clear solution was filtered into a test
tube, after several days colorless block crystals formed, which was
filtered off, washed with MeOH and dried under vacuum to afford
0.044 g of the product. Yield: 44% (Cd(CH3COO)2Á2H2O). Elemental
analysis performed on crystals exposed to the atmosphere: Anal.
Calc. for C82H126Cd3N20O18 (2017.23): C, 48.78; H, 6.24; N, 13.88.
Found: C, 48.72; H, 6.16; N, 13.83%. Infrared spectrum (KBr disc,
A suitable crystal for single crystal X-ray analysis was mounted
on a glass fiber on a Bruker SMART 1000 CCD diffractometer oper-
ating at 50 kV and 40 mA using Mo Ka radiation (0.71073 Å). Data
collection and reduction were performed using the SMART and SAINT
software [22]. The structures were solved by direct methods, and
the non-hydrogen atoms were subjected to anisotropic refinement
by full-matrix least squares on F2 using SHELXTL package [23]. Hydro-
gen atom positions for all of the structures were found in a differ-
ence map. Further details of the structural analysis are
summarized in Tables 1 and 2. Selected bond lengths and angles
for complexes 1–6 are listed in Table 3, and the relevant hydrogen
bond parameters are provided in Table 4.
cmÀ1): 3577s(
m
(OH)), 3436m, 3245m, 3119m, 2935s, 2858m,
(C@O)), 1627s, 1609s(
as(COOÀ)), 1548m, 1498s,
s(COOÀ)), 1365m, 1295s(
(C–O)), 1267m, 1174m, 1094m,
1664s(
1421s(
m
m
m
3. Results and discussion
m
936m, 894m, 831m, 744m, 681m, 627m.
3.1. Preparation and general characterization
2.2.6. Synthesis of Zn(Hdmpz)2(L6) (6)
Complexes 1–6 were prepared in MeOH or EtOH system under
room temperature via combination of the metal acetate, Hdmpz
group, and the corresponding carboxylic acid. The corresponding
crystals suitable for X-ray crystallography analysis were grown
upon addition of a few drops of conc. ammonia solution with yields
of 57–76%.
A solution of Zn(CH3COO)2Á2H2O (0.022 g, 0.10 mmol) in 5 mL
of EtOH was added to a MeOH solution (4 mL) containing Hdmpz
(0.019 g, 0.20 mmol) and sebacic acid (H2L6) (0.040 g, 0.20 mmol),
under continuous stirring. The solution was stirred for about 2 h at
room temperature, the solution became turbid, then a few drops of
conc. ammonia was added till the solution became clear com-
pletely. The clear solution was filtered into a test tube, after several
During the process the acetate has been substituted by the
corresponding carboxylate ions, and all Hdmpzs retain their NH
Table 1
Summary of X-ray crystallographic data for complexes 1–3.
1
2
3
Formula
Fw
C
22H24CdN6O4
C36H36N6O4Zn
682.08
C30H32N6O6Zn
637.99
548.87
T (K)
298(2)
298(2)
298(2)
Wavelength (Å)
Crystal system
space group
a (Å)
b (Å)
c (Å)
0.71073
monoclinic
P21/c
9.8418(5)
8.8992(7)
13.3314(11)
90
104.2780(10)
90
1131.55(14)
2
1.611
1.007
556
0.71073
0.71073
monoclinic
P21/n
11.7551(12)
14.2725(16)
18.0856(19)
90
94.7860(10)
90
3023.7(6)
4
1.401
0.865
1328
triclinic
ꢀ
P1
7.8060(6)
14.5599(13)
16.0201(15)
109.088(2)
91.9730(10)
94.4300(10)
1712.1(3)
2
a
(°)
b (°)
c
(°)
V (Å3)
Z
Dcalc (Mg/m3)
Absorption coefficient (mmÀ1
F(000)
1.323
0.764
712
)
Crystal size (mm)
h Range (°)
Limiting indices
0.32 Â 0.19 Â 0.12
2.78–25.02
À8 6 h 6 11
À10 6 k 6 10
À15 6 l 6 15
5783
0.33 Â 0.19 Â 0.16
2.31–25.02
À9 6 h 6 9
À17 6 k 6 17
À11 6 l 6 19
8748
0.41 Â 0.29 Â 0.21
2.25–25.02
À13 6 h 6 13
À16 6 k 6 12
À20 6 l 6 21
14844
Reflections collected
Reflections independent (Rint
)
1992 (0.0864)
0.972
5968 (0.0389)
1.040
5322 (0.0419)
1.031
Goodness-of-fit (GOF) on F2
R indices [I > 2
R indices (all data)
Largest difference peak and hole (e ÅÀ3
r
I]
0.0499, 0.1224
0.0654, 0.1338
1.376, À0.797
0.0557, 0.1038
0.1252, 0.1318
0.336, À0.413
0.0350, 0.0773
0.0628, 0.0927
0.300, À0.265
)

34
S. Jin, D. Wang / Inorganica Chimica Acta 415 (2014) 31–43
Table 2
Summary of X-ray crystallographic data for complexes 4–6.
4
5
6
Formula
Fw
T( K)
C
34H40CdCl2N8O6
C82H126Cd3N20O18
2017.23
298(2)
C20H32N4O4Zn
457.87
298(2)
840.04
298(2)
Wavelength (Å)
Crystal system
Space group
a (Å)
b (Å)
c (Å)
0.71073
0.71073
0.71073
monoclinic
P21/c
15.6548(12)
8.8600(6)
17.7947(14)
90
112.7090(10)
90
2276.8(3)
4
1.336
1.110
968
triclinic,
triclinic,
ꢀ
ꢀ
P1
P1
9.3950(10)
9.7139(11)
11.2071(12)
106.699(2)
90.4330(10)
105.078(2)
942.17(18)
1
9.9600(8)
14.2769(13)
17.1141(16)
93.5620(10)
90.1790(10)
99.931(2)
2392.3(4)
1
1.400
0.733
1046
a
(°)
b (°)
c
(°)
V (Å3)
Z
Dcalc (Mg/m3)
1.481
0.775
430
Absorption coefficient (mmÀ1
F(000)
)
Crystal size (mm)
h Range (°)
0.36 Â 0.25 Â 0.16
2.28–25.02
À11 6 h 6 10
À9 6 k 6 11
À13 6 l 6 13
4740
0.46 Â 0.35 Â 0.32
2.38–25.02
À11 6 h 6 11
À16 6 k 6 16
À13 6 l 6 20
11876
0.28 Â 0.18 Â 0.15
2.48–25.01
À18 6 h 6 18
À10 6 k 6 10
À15 6 l 6 21
11108
Limiting indices
Reflections collected
Reflections independent (Rint
)
3276 (0.0242)
1.085
8275 (0.0495)
1.017
4024 (0.0488)
1.043
Goodness-of-fit (GOF) on F2
R indices [I > 2
R indices (all data)
Largest difference peak and hole (e ÅÀ3
r
I]
0.0371, 0.0905
0.0419, 0.0954
0.844, À0.626
0.0677, 0.1650
0.1111, 0.2042
1.441, À2.010
0.0504, 0.1212
0.0977, 0.1507
0.400, À0.429
)
groups. These compounds are not soluble in almost all common
solvents. The infrared spectra of 1–6 were fully consistent with
their formulations. The IR spectra of 1–6 display the characteristic
tion in respect to the C atoms they are attached. The coordination
mode of the nicotinate is similar to the reported compound of
[Zn(L1)2]n [26]. The two pyrazole ligands coordinated to the same
Cd ion are in trans arrangement, so do the two carboxylate ligands
coordinated to the same Cd ion.
The location of the H3 in 1, binding nitrogen but not oxygen, is
consistent with the different acidic characters of pyrazole and nic-
otinic acid [27], and also confirmed by the difference electron den-
sity map which found the H atoms. The Cd–N distances are
2.331(4) Å (Cd–Npyrazole) and 2.419(4) Å (Cd–Npyridine), respectively,
the Cd–O distance is 2.364(3) Å, which are all in the bond length
ranges of the reported compounds [28]. Yet the Cd–Npyrazole bond
is shorter than the Cd–Npyridine bond. The angles around the Cd
atom range from 86.93(13)° to 93.07(13)°.
Moreover 1 is not an ionic species consisting of monocationic
Cd(II) complex and carboxylate counterions. In 1, the non-bonded
oxygen atom, far enough from the Cd ion with distance of 3.67 Å, is
involved in the intramolecular hydrogen bond (N(3)–
H(3)Á Á ÁO(2)#2, #2 Àx,yÀ1/2,Àz À 1/2) with the N–O distance of
2.642(5) Å and H–O distance of 1.81 Å.
carboxylate bands in the range 1596–1627 cmÀ1 for
m
as(CO2) and at
s(CO2) [24]. The frequency differences be-
s(CO2) are in the range of 188–209 cmÀ1 for
1402–1422 cmÀ1 for
tween as(CO2) and
m
m
m
all of the compounds. This suggests unidentate coordination mode
for the carboxylate ligands in all of the compounds. Compound 5
contains additional carboxyl group with the chelating bidentate
coordination mode with the
mas(CO2) and ms(CO2) bands at 1627,
and 1498 cmÀ1 (with the value of 129 cmÀ1), respectively. Com-
D
pound 5 also displays strong IR peaks for the COOH groups. There
are coordinated neutral Hmdpzs in all of the six compounds which
is further confirmed by the presence of the characteristic NH bands
in the region 3500–3200 cmÀ1 [25]. Weak absorptions observed at
3000–2800 cmÀ1 can be attributed to the aromatic C–H and the
olefinic CH group of L3, respectively.
3.2. Crystal structure description
3.2.1. Crystal and molecular structure of Cd(Hdmpz)2(L1)2 (1)
The compound 1 prepared by reaction of Cd(CH3COO)2Á2H2O,
nicotinic acid (HL1), and Hdmpz in MeOH solvents with ratios of
1:2:4 yields pure Cd(Hdmpz)2(L1)2 upon addition of a few drops
of conc. ammonia solution. The structural determination revealed
that Cd, L1, and Hdmpz are present in a 1:2:2 ratio in the molecular
complex 1, and the asymmetric unit is shown in Fig. 1. The com-
plex 1 crystallizes in the monoclinic system with space group
P21/c.
The dihedral angle between the pyrazole ring and the pyridine
ring of the L1 is 76.3°. The carboxylate O1–C1–O2 rotated about
5.4° from the pyridine ring plane of the anion.
The compound 1 displays 2D sheet structure extending along
the bc plane, which is shown in Fig. 2. In the sheet there exist
CH–O interaction between the 2-CH of one anion and the uncoor-
dinated O atom of the other anion with C–O distance of 3.228 Å,
CH3–O association between the 3-CH3 group of the pyrazole and
the uncoordinated O atom of the carboxylate with C–O distance
Each Cd ion is octahedrally coordinated by two oxygen atoms of
two monodentate L1 ligands, two nitrogen atoms from two L1 li-
gands, and two nitrogen atoms belonging to two different monoden-
tate pyrazole ligands (Fig. 1). Herein the nicotinate coordinated to
two different Cd ions in bismonodentate fashion with its N and
one O atom of the carboxylate, respectively. Herein the coordinated
N atom and the carboxylate in the same anion are in trans conforma-
of 3.397 Å, and p–p association between the aromatic rings of
the anions with Cg–Cg distance of 3.393 Å. In the sheet the Cd–
Cd separations between the neighboring Cd ions are 8.014 and
8.899 Å, respectively. The 2D sheets were further stacked along
the a axis direction via the CH3–p association between 5-CH3 of
the pyrazole and the aromatic ring of the anion with C–Cg distance
of 3.500 Å to form 3D network structure.

S. Jin, D. Wang / Inorganica Chimica Acta 415 (2014) 31–43
35
Table 3
Table 3 (continued)
Selected bond lengths (Å) and angles (°) for 1–6.
O(4)#1–Cd(1)–N(3) 103.4(2)
O(4)#1–Cd(1)–N(1)
O(4)#1–Cd(1)–O(2)
N(1)–Cd(1)–O(2)
N(3)–Cd(1)–N(5)
O(2)–Cd(1)–N(5)
N(3)–Cd(1)–O(1)
O(2)–Cd(1)–O(1)
N(7)#2–Cd(2)–N(9)
N(7)–Cd(2)–O(5)#2
N(7)–Cd(2)–O(5)
O(1)–C(1)–O(2)
102.6(2)
142.50(18)
82.19(18)
99.2(2)
78.78(17)
166.50(19)
53.45(15)
95.1(2)
90.98(19)
89.02(19)
121.6(6)
123.9(7)
1
N(3)–Cd(1)–N(1)
N(3)–Cd(1)–O(2)
O(4)#1–Cd(1)–N(5) 89.1(2)
N(1)–Cd(1)–N(5) 160.1(2)
O(4)#1–Cd(1)–O(1) 89.28(17)
N(1)–Cd(1)–O(1)
N(5)–Cd(1)–O(1)
N(7)–Cd(2)–N(9)
93.8(2)
113.5(2)
Cd(1)–N(2)
Cd(1)–N(1)
N(1)–C(2)
N(2)–N(3)
O(1)–C(1)
N(2)#1–Cd(1)–N(2) 180.0(2)
N(2)–Cd(1)–O(1)#2 91.46(13)
N(2)#1–Cd(1)–N(1) 87.52(14)
O(1)#2–Cd(1)–N(1) 93.07(13)
2.331(4)
2.419(4)
1.337(6)
1.353(6)
1.255(6)
Cd(1)–O(1)#2
N(1)–C(6)
N(2)–C(8)
N(3)–C(10)
O(2)–C(1)
N(2)#1–Cd(1)–O(1)#2 88.54(13)
O(1)#2–Cd(1)–O(1)#3 180.00(15)
2.364(3)
1.327(6)
1.332(6)
1.346(6)
1.248(5)
87.92(17)
76.04(17)
84.9(2)
N(2)–Cd(1)–N(1)
O(1)#3–Cd(1)–N(1)
92.48(14)
86.93(13)
117.5(4)
N(9)–Cd(2)–O(5)#2 87.08(18)
N(9)–Cd(2)–O(5)
O(3)–C(2)–O(4)
O(7)–C(10)–O(8)
92.92(18)
122.8(8)
123.8(7)
N(1)–Cd(1)–N(1)#1 180.00(18) C(6)–N(1)–C(2)
O(2)–C(1)–O(1)
O(5)–C(9)–O(6)
125.4(5)
2
6
Zn(1)–O(1)
Zn(1)–N(3)
N(1)–C(3)
N(2)–C(16)
N(3)–C(28)
N(4)–C(30)
N(5)–N(6)
1.920(3)
1.994(4)
1.384(5)
1.375(5)
1.331(6)
1.324(5)
1.347(4)
1.265(5)
1.267(5)
104.33(14) O(1)–Zn(1)–N(3)
105.13(14) O(1)–Zn(1)–N(5)
114.54(14) N(3)–Zn(1)–N(5)
129.9(4)
123.9(5)
Zn(1)–O(3)
Zn(1)–N(5)
N(1)–C(8)
N(2)–C(21)
N(3)–N(4)
N(5)–C(33)
N(6)–C(35)
O(2)–C(1)
O(4)–C(14)
1.941(3)
1.998(4)
1.401(5)
1.388(5)
1.348(4)
1.331(5)
1.334(5)
1.250(5)
1.247(5)
114.71(15)
103.47(15)
114.48(15)
131.3(4)
123.0(5)
Zn(1)–O(1)
Zn(1)–N(3)
N(1)–C(12)
N(2)–C(14)
N(3)–N(4)
1.923(3)
1.998(4)
1.323(6)
1.341(6)
1.364(5)
1.278(5)
1.272(5)
104.18(14) O(1)–Zn(1)–N(3)
110.12(16) O(1)–Zn(1)–N(1)
113.60(15) N(3)–Zn(1)–N(1)
Zn(1)–O(3)
Zn(1)–N(1)
N(1)–N(2)
N(3)–C(17)
N(4)–C(19)
O(2)–C(1)
O(4)–C(10)
1.927(3)
2.012(4)
1.357(5)
1.328(6)
1.344(6)
1.218(5)
1.226(5)
110.09(15)
108.58(16)
110.09(16)
124.8(5)
O(1)–C(1)
O(3)–C(10)
O(1)–Zn(1)–O(3)
O(3)–Zn(1)–N(3)
O(3)–Zn(1)–N(1)
O(2)–C(1)–O(1)
O(1)–C(1)
O(3)–C(14)
O(1)–Zn(1)–O(3)
O(3)–Zn(1)–N(3)
O(3)–Zn(1)–N(5)
C(3)–N(1)–C(8)
O(2)–C(1)–O(1)
124.9(4)
O(4)–C(10)–O(3)
Symmetry transformations used to generate equivalent atoms for 1: #1 Àx,Ày,Àz;
#2 Àx,y À 1/2,Àz À 1/2; #3 x,Ày + 1/2,z + 1/2. Symmetry transformations used to
generate equivalent atoms for 4: #1 Àx + 1,Ày + 1,Àz. Symmetry transformations
used to generate equivalent atoms for 5: #1 Àx + 1,Ày + 1,Àz + 1; #2 Àx + 1,
Ày,Àz.
C(16)–N(2)–C(21)
O(4)–C(14)–O(3)
3
Zn(1)–O(4)
Zn(1)–N(5)
N(1)–C(4)
N(2)–C(14)
N(3)–C(22)
N(4)–C(24)
N(5)–N(6)
1.9423(19) Zn(1)–O(1)
1.9600(18)
2.034(2)
1.411(3)
1.414(3)
1.357(3)
1.331(3)
1.342(3)
1.218(3)
1.267(3)
1.231(3)
108.57(9)
125.24(9)
105.00(9)
129.1(2)
124.1(3)
1.999(2)
1.354(3)
1.347(3)
1.340(3)
1.338(3)
1.364(3)
1.266(3)
1.224(3)
1.230(3)
112.96(8)
109.17(8)
94.56(8)
129.1(2)
126.6(2)
Zn(1)–N(3)
N(1)–C(5)
N(2)–C(15)
N(3)–N(4)
N(5)–C(27)
N(6)–C(29)
O(2)–C(1)
O(4)–C(11)
Table 4
Hydrogen bond distances and angles in studied structures of 1–6.
O(1)–C(1)
O(3)–C(4)
D–HÁ Á ÁA
1
N(3)–H(3)Á Á ÁO(2)#2
2
N(6)–H(6)Á Á ÁO(4)
N(4)–H(4)Á Á ÁO(2)
N(2)–H(2)Á Á ÁO(4)
N(1)–H(1)Á Á ÁO(2)
d(D–H) (Å) d(HÁ Á ÁA) (Å) d(DÁ Á ÁA) (Å) <(DHA)(°)
O(5)–C(11)
O(4)–Zn(1)–O(1)
O(1)–Zn(1)–N(5)
O(1)–Zn(1)–N(3)
C(4)–N(1)–C(5)
O(2)–C(1)–O(1)
O(6)–C(14)
0.86
1.81
2.642(5)
162.9
O(4)–Zn(1)–N(5)
O(4)–Zn(1)–N(3)
N(5)–Zn(1)–N(3)
C(14)–N(2)–C(15)
O(5)–C(11)–O(4)
0.86
0.86
0.86
0.86
1.87
1.88
1.87
1.93
2.655(5)
2.678(5)
2.594(5)
2.636(5)
150.8
152.9
141.5
138.1
4
Cd(1)–O(1)
Cd(1)–N(1)
N(1)–N(2)
N(3)–C(14)
N(4)–C(16)
O(2)–C(1)
O(1)#1–Cd(1)–O(1) 180.00(9)
O(1)–Cd(1)–N(3) 91.22(9)
O(1)–Cd(1)–N(1)#1 88.60(9)
2.321(2)
2.383(2)
1.357(3)
1.329(4)
1.334(4)
1.246(4)
Cd(1)–N(3)
N(1)–C(9)
N(2)–C(11)
N(3)–N(4)
O(1)–C(1)
O(3)–C(3)
O(1)–Cd(1)–N(3)#1
N(3)#1–Cd(1)–N(3)
N(3)–Cd(1)–N(1)#1
N(3)#1–Cd(1)–N(1)
N(1)#1–Cd(1)–N(1)
2.353(3)
1.331(4)
1.341(4)
1.362(3)
1.275(4)
1.344(4)
88.78(9)
180.0
3
N(6)–H(6)Á Á ÁO(6)
N(4)–H(4)Á Á ÁO(3)
N(2)–H(2)Á Á ÁO(2)#1
N(1)–H(1)Á Á ÁO(5)#2
0.86
0.86
0.86
0.86
2.06
1.92
2.12
1.99
2.900(3)
2.774(3)
2.934(3)
2.831(3)
167.0
171.9
158.4
164.1
4
O(3)–H(3)Á Á ÁO(1)
N(4)–H(4)Á Á ÁO(2)
N(2)–H(2)Á Á ÁO(2)
0.82
0.86
0.86
1.85
2.01
1.98
2.564(4)
2.835(4)
2.804(4)
145.3
159.6
159.0
86.87(9)
86.87(9)
180.0
O(1)–Cd(1)–N(1)
N(3)–Cd(1)–N(1)
O(2)–C(1)–O(1)
91.40(9)
93.13(9)
124.3(3)
5
O(9)–H(9D)Á Á ÁO(3)#3
O(9)–H(9C)Á Á ÁO(6)
O(8)–H(8A)Á Á ÁO(2)#4
0.85
0.85
0.82
2.05
2.03
1.72
1.92
1.90
2.23
1.87
2.45
2.20
2.877(10)
2.858(9)
2.530(7)
2.756(8)
2.747(8)
2.983(7)
2.713(9)
2.988(7)
2.991(8)
164.9
164.9
172.4
163.8
166.7
146.1
167.1
121.5
153.2
5
Cd(1)–O(4)#1
Cd(1)–N(1)
Cd(1)–N(5)
Cd(2)–N(7)
Cd(2)–O(5)
N(1)–N(2)
N(3)–C(23)
N(4)–C(25)
N(5)–N(6)
N(7)–C(31)
N(8)–C(33)
N(9)–N(10)
O(1)–C(1)
O(3)–C(2)
O(5)–C(9)
O(7)–C(10)
2.193(5)
2.333(5)
2.366(5)
2.338(6)
2.387(5)
1.349(8)
1.312(10)
1.342(10)
1.350(7)
1.326(9)
1.322(9)
1.348(8)
1.243(8)
1.239(9)
1.252(8)
1.202(8)
Cd(1)–N(3)
Cd(1)–O(2)
Cd(1)–O(1)
Cd(2)–N(9)
N(1)–C(18)
N(2)–C(20)
N(3)–N(4)
N(5)–C(28)
N(6)–C(65)
N(7)–N(8)
N(9)–C(36)
N(10)–C(38)
O(2)–C(1)
2.254(6)
2.360(4)
2.513(5)
2.357(6)
1.315(9)
1.339(9)
1.358(8)
1.326(8)
1.338(8)
1.359(7)
1.340(9)
1.330(9)
1.272(8)
1.268(8)
1.265(9)
1.320(8)
N(10)–H(10)Á Á ÁO(6)#2 0.86
N(8)–H(8)Á Á ÁO(6)
N(6)–H(6)Á Á ÁO(1)#1
N(4)–H(4)Á Á ÁO(3)#1
N(2)–H(2)Á Á ÁO(2)
N(2)–H(2)Á Á ÁO(7)#5
0.86
0.86
0.86
0.86
0.86
6
N(4)–H(4)Á Á ÁO(2)
0.86
0.86
1.88
1.92
2.704(5)
2.692(5)
158.7
149.3
N(2)–H(2)Á Á ÁO(4)
Symmetry transformations used to generate equivalent atoms for 1: #2 Àx,y À 1/
2,ÀzÀ1/2. Symmetry transformations used to generate equivalent atoms for 3: #1
Àx + 2,Ày,Àz + 1; #2 xÀ1/2,Ày + 1/2,zÀ1/2. Symmetry transformations used to
generate equivalent atoms for 5: #1 Àx + 1,Ày + 1,Àz + 1; #2 Àx + 1,Ày,Àz; #3
Àx + 2,Ày + 1,Àz + 1; #4 x,y À 1,z; #5 x,y + 1,z.
O(4)–C(2)
O(6)–C(9)
O(8)–C(10)

36
S. Jin, D. Wang / Inorganica Chimica Acta 415 (2014) 31–43
Fig. 1. Molecular structure of complex 1 showing the atomic numbering scheme at 30% ellipsoid probability level.
Fig. 2. Packing diagram of compound 1 showing the 2D sheet structure extending along the bc plane.
3.2.2. Crystal and molecular structure of Zn(Hdmpz)2(L2)2 (2)
Crystals of 2 contain mononuclear complex of Zn(Hdmpz)2(L2)2
formulation (Fig. 3). Compound 2 crystallizes in the triclinic space
(ML)2] monomers, in which ML is a monodentate nitrogen ligand,
such as imidazole [29] and pyridine [30].
The ZnN2O2 unit possesses coordination distances and angles in
the ranges of 1.920(3)–1.998(4) Å and 104.33(14)–114.71(15)°,
respectively; thus, the overall coordination geometry resembles
that found in the compounds {[Zn(CH3COO)2(Hpz)2]ÁCH3COOH}
(Hpz = pyrazole) [19a], and [Zn(Hpz)2(Me3NCH2CO2)](ClO4)2
[19d]. Although the distortion in the ZnN2O2 moiety is differently
ꢀ
group P1, and there are 2 formula units in its cell content. Each zinc
ion is tetrahedrally coordinated by two oxygen atoms of two
monodentate L2 ligands and by two nitrogen atoms, belonging to
two monodentate pyrazole ligands with ZnN2O2 binding set. The
molecular structure of 2 resembles the related [Zn(CH3COO)2

S. Jin, D. Wang / Inorganica Chimica Acta 415 (2014) 31–43
37
Fig. 3. Molecular structure of complex 2 showing the atomic numbering scheme at 30% ellipsoid probability level.
oriented in the later two compounds, the angles around zinc atoms
are 98.94(19)–117.30(18)° and 95.73(7)–118.34(8)°, respectively.
In 2, the non-bonded oxygen atoms, far enough from the zinc
with distances of 3.138 and 3.238 Å, respectively, are involved in
two intramolecular hydrogen bonds (N(6)–H(6)Á Á ÁO(4), and N(4)–
H(4)Á Á ÁO(2)) with the N–O distances ranging from 2.655(5) to
2.678(5) Å and H–O distances of 1.87–1.88 Å. In addition to the
intramolecular N–HÁ Á ÁO hydrogen bonds produced by the N–H
moieties of the pyrazole, there also exists intramolecular N–
HÁ Á ÁO hydrogen bond (Table 4) in the anion between the NH group
and the non-bonded oxygen atom of the same L2 to produce a S11(6)
loop motif according to Bernstein [31]. Thus the non-bonded oxy-
gen atom forms two hydrogen bonds in bifurcate mode.
The dihedral angle between the two pyrazole rings with N3 and
N4, and N5 and N6 atoms was 120.5°. The phenyl ring bearing C2–
C7 atoms made dihedral angles of 7.7° and 113.6° with the above
two pyrazole rings, respectively. The phenyl ring bearing C8–C13
made dihedral angles of 50.5° and 72.8° with the two pyrazole
rings bearing N3 and N4, and N5 and N6, respectively. The phenyl
ring bearing C15–C20 atoms made dihedral angles of 96.7° and
26.9° with the pyrazole rings bearing N3 and N4, and N5 and N6
atoms, respectively. The phenyl ring bearing C21–C26 atoms inter-
sected at angles of 133° and 18.5° with the above two pyrazole
rings, respectively.
The C(2)@C(3) and C(12)@C(13) bond distances (1.323(3) and
1.322(4) Å) are apparently for a simple C@C double bond, due to
the significant non-coplanarity of the carboxyl and the olefinic
groups (herein the carboxyl group is almost perpendicular with
the plane defined by the amide and the olefinic groups which is dif-
ferent from the crystal of N-phenylmaleamic acid [32]). But the
C(2)@C(3) and C(12)@C(13) bond distances are somewhat short-
ened compared with the corresponding values (1.335 and
1.344 Å) in the neutral molecule of N-phenylmaleamic acid [32].
The C–O bond distances (O(1)–C(1),1.266(3) Å; O(4)–C(11),
1.267(3) Å) involving the O atoms that coordinated to the Zn are
longer than the C–O bond distances (O(2)–C(1), 1.218(3) Å; O(5)–
C(11), 1.230(3) Å) that did not coordinate with the Zn, although
they form some nonbonding interactions. The reason may be that
the coordinate bonds are stronger than the weak nonbonding
interactions.
The phenyl rings composed of C5–C10 and C15–C20 in the two
anions intersected at an angle of 78° with each other. The pyrazole
ring with N3 and N4 atoms made dihedral angles of 55.1° and
124.2° with the phenyl rings of the above two anions, respectively.
The pyrazole ring with N5 and N6 atoms made dihedral angles of
71.5° and 38.1° with the phenyl rings of the two anions, respec-
tively. The pair of pyrazoles coordinated to the same Zn has dihe-
dral angle of 126.2°. The dihedral angles between the phenyl rings
and the amide groups (–NHCO–) in the same anion are 3.7° (for the
amide group H1AN1AC4@O3) and 4.4° (for the amide group
H2AN2AC14@O6), respectively. The conformation of the N–H
and C@O bonds in the amide segment of the structure is anti to
each other. Further, the conformation of the amide O atom is anti
to the H atom attached to the adjacent C atom (Fig. 5).
Two mononuclear units are combined together via the CH–
p
association between the phenyl CH of the anion and the phenyl
ring of adjacent mononuclear moiety with C–Cg distance of
3.732 Å to form a dinuclear aggregate. In the dinuclear aggregate
the Zn–Zn distance is 8.982 Å, and there existed an inversion
centre at the middle point of the two Zn ions. The dinuclear aggre-
gates were linked together via the CH–
p
association between the
The ZnN2O2 moiety possesses coordination distances and angles
in the ranges of 1.9423(19)–2.034(2) Å and 94.56(8)–125.24(9)°,
respectively; thus, the overall coordination geometry resembles
that found in the compounds 2, {[Zn(CH3COO)2(Hpz)2]ÁCH3COOH}
(Hpz = pyrazole) [19a], and [Zn(Hpz)2(Me3NCH2CO2)](ClO4)2
[19d]. Although the distortion in the ZnN2O2 moiety is differently
oriented in the later two compounds, the angles around the zinc
atoms are in the range of 98.94(19)–117.30(18)° and 95.73(7)–
118.34(8)°, respectively. Compound 3 is not an ionic species con-
sisting of monocationic zinc(II) complex and carboxylate counteri-
ons, either. In 3, the non-bonded oxygen atoms, far enough from
the zinc ions with distances of 2.868 and 3.162 Å, respectively,
are not involved in the intramolecular hydrogen bonds. But the
carbonyl units in the amide groups are involved in the intramolec-
ular N–HÁ Á ÁO hydrogen bonds (N(4)–H(4)Á Á ÁO(3), 1.92 Å,
2.774(3) Å; and N(6)–H(6)Á Á ÁO(6), 2.06 Å, 2.900(3) Å).
phenyl CH of the anion and the phenyl ring of the adjacent mono-
nuclear moiety with C–Cg distance of 3.732 Å to form a 1D chain
running along the b axis direction (Fig. 4). The chains were ar-
ranged parallel to each other on the ab plane forming 2D sheet
structure, yet there were no connections between these chains in
the 2D sheet.
3.2.3. Crystal and molecular structure of Zn(Hdmpz)2(L3)2 (3)
Compound 3 of the formula Zn(Hdmpz)2(L3)2 crystallizes in the
monoclinic space group P21/n with the 4 formula units in the unit
cell. Each zinc ion is tetrahedrally coordinated by two oxygen
atoms of two monodentate L3 ligands and by two nitrogen atoms
of two different monodentate pyrazole ligands (Fig. 5).
The molecular structure of 3 resembles compound 2, and the re-
lated [Zn(CH3COO)2(ML)2] monomers (ML = a monodentate nitro-
gen ligand) also, like the bisimidazole [29] and bis-pyridine [30]
complexes.
The mononuclear units were linked together in head to tail
fashion via the C–HÁ Á ÁO associations between the phenyl CH

38
S. Jin, D. Wang / Inorganica Chimica Acta 415 (2014) 31–43
Fig. 4. The 1D chain structure of 2 running along the b axis direction which is formed through the CH–p associations between the dinuclear aggregates.
Fig. 5. Molecular structure of complex 3 showing the atomic numbering scheme at 30% ellipsoid probability level.
group of the anion and the noncoordinated O atom of the car-
boxylate and the O atom at the CONH with C–O distances of
3.439–3.549 Å to form 1D chain running along the a axis direc-
tion. Two neighboring chains were linked together by the C–
HÁ Á ÁO association between the phenyl CH of the anion and the
non-coordinated O atom of the carboxylate with C–O distance
of 3.430 Å, N–HÁ Á ÁO hydrogen bond between the amide NH
and the non-bonded O atom of the carboxylate with N–O dis-
ring of the anion made dihedral angles of 58.3° and 127.4° with
the above two pyrazole rings, respectively.
In 4, the non-bonded oxygen atom, far enough from the Cd ion
with distance of 3.699 Å, is involved in two intramolecular hydro-
gen bonds (N(2)–H(2)Á Á ÁO(2), and N(4)–H(4)Á Á ÁO(2) with the N–O
distances ranging from 2.804(4) to 2.835(4) Å and H–O distances
of 1.98–2.01 Å. Because of the presence of the intramolecular
hydrogen bond between the carboxylate group and the phenol
group (O(3)–H(3)Á Á ÁO(1), 2.564(4) Å) in the anion, it is generally
expected and found that the carboxylate group is essentially copla-
nar with the benzene ring [torsion angle C3–C2–C1–O2, 179.34°].
For the presence of this O–HÁ Á ÁO hydrogen bond (Table 4) between
the phenol group and the coordinated oxygen atom of L4, there ex-
ists a S11(6) loop motif in the anion. This feature is similar to that
found in the salicylic acid [33], and in the previously reported
structure of deprotonated compound based on o-hydroxy benzoic
acid derivatives [34]. As expected the O–O separation
(2.564(4) Å) is essentially in the range of the documented data
[2.531(4)–2.570(4) Å] [35] because of the planarity of the hydro-
gen bonded carboxylate unit, but it is slightly contracted compared
with the nondeprotonated examples (2.547–2.604, mean: 2.588 Å),
as a result of deprotonation.
The mononuclear units were linked together via the CH3–O inter-
actions between the 5-CH3 group of the pyrazole and the phenol
group with C–O distance of 3.114 Å to form a 1D chain running along
the b axis direction. Such kind of chains were joined together by the
Cl–O contact between the Cl atom and the uncoordinated O atom of
the carboxylate with Cl–O distance of 3.240 Å to form 2D corrugated
sheet extending in the direction that formed a dihedral angle of ca.
45° with the ab plane (Fig. 8). Herein the Cl–O contact is weaker than
that found in 5-chloro-1,2-dimethyl-4-nitro-1H-imidazole [36].
Thus the non-bonded oxygen atom forms two hydrogen bonds in
bifurcate mode. The sheets were further stacked along the direction
that is perpendicular with its extending direction to form 3D net-
work structure. However there are no associations between the
neighboring sheets.
tance of 2.934(3) Å, and C–HÁ Á Á
p association between the ole-
finic CH of the anion and the aromatic ring of the anion with
C–Cg distance of 3.486 Å to form 1D flat pipe structure running
along the a axis direction. The 1D flat pipes were joined to-
gether by the CH3Á Á Á
p interaction between the 3-CH3 of the pyr-
azole and the aromatic ring of the anion with C–Cg distance of
3.544 Å to form 2D sheet extending parallel to the ab plane
(Fig. 6). The 2D sheets were further stacked along the c axis
direction via the C–HÁ Á ÁO association between the olefinic CH
of the anion and the C@O of the amide with C–O distance of
3.391 Å, N–HÁ Á ÁO hydrogen bond between the amide group
and the uncoordinated O atom of the carboxylate with N–O dis-
tance of 2.831(3) Å, and CH3Á Á ÁO association between the 5-CH3
of the pyrazole and the uncoordinated O atom of the carboxyl-
ate with C–O distance of 3.376 Å to form 3D layer network
structure.
3.2.4. Crystal and molecular structure of Cd(Hdmpz)4(L4)2 (4)
Compound 4 crystallizes in the triclinic system with space
ꢀ
group P1. An asymmetric unit of Cd(Hdmpz)4(L4)2 contains one
six-coordinated Cd(II) ion, a L4 anion, and two Hdmpz groups,
which is shown in Fig. 7. The Cd atom is at (0.5, 0.5, 0). The Cd–
O distance is 2.321(2) Å, the Cd–N distances are 2.353(3) and
2.383(2) Å, respectively, which are similar to the corresponding
bond distances in 1.
The pyrazole rings containing the N1 and N2, and N3 and N4
atoms inclined at an angle of 69.2° with each other. The phenyl

S. Jin, D. Wang / Inorganica Chimica Acta 415 (2014) 31–43
39
Fig. 6. 2D sheet structure of 3 extending parallel to the ab plane.
C(10)
C(8)
C(9)
C(11)
C(15)
N4
C(12)
C(14)
C(13)
C(5)
C(17)
C(16)
N(3)
Cl(1)
C(4)
C(2)
N(1)
C(6)
N(2)
O(3)
C(3)
O(1)
C(7)
C(1)
Cd(1)
O(2)
Fig. 7. Molecular structure of complex 4 showing the atomic numbering scheme at 30% ellipsoid probability level, the H atoms were omitted for clarity.
Fig. 8. 2D corrugated sheet structure of compound 4.

40
S. Jin, D. Wang / Inorganica Chimica Acta 415 (2014) 31–43
Fig. 9. Molecular structure of complex 5 showing the atomic numbering scheme at 30% ellipsoid probability level. Atom-numbering and H atoms were omitted for clarity.
3.2.5. Crystal and molecular structure of
Cd2(Hdmpz)6(L5)2Cd(Hdmpz)4(HL5)2Á2H2O (5)
COOH groups, which further confirms our correct assignment of
the H atom that is attached to the carboxyl group. Herein the cyclo-
hexane rings of the anions adopt chair conformation with the two
carboxyl units in e, a positions, respectively.
The mononuclear units and the dinuclear units were linked to-
gether to form 1D chain. The mononuclear units and the dinuclear
units alternate at the chain. In the chain there exist CH–p interac-
tion between the 4-CH of the pyrazole in the dinuclear unit and the
aromatic ring of the pyrazole in the mononuclear unit with C–Cg
The asymmetric unit of 5 consists of half of dinuclear unit with
the formula of Cd2(Hdmpz)6(L5)2, half of mononuclear unit of
Cd(Hdmpz)4(HL5)2, and one water molecule (Fig. 9). In the dinucle-
ar unit the Cd atom is coordinated with three N atoms from three
pyrazole molecules and three O atoms of the carboxylate to form a
CdN3O3 bonding set. The carboxylate groups in the L5 coordinated
to the Cd in two modes, one carboxylate coordinated to the metal
centre in unidentate fashion, while the other carboxylate coordi-
nated to the Cd in bidentate chelating fashion. In the asymmetry
moiety of the mononuclear unit Cd(Hdmpz)4(HL5)2, there existed
two neutral Hdmpz molecules, and one hydrogen 1,4-cyclohexan-
edicarboxylate. In the hydrogen 1,4-cyclohexanedicarboxylate the
deprotonated carboxyl coordinated to the Cd in unidentate mode,
the pyrazole coordinated to the Cd in monodentate fashion.
The C–O bond lengths of the COOH (O(8)–C(10)–O(7)) group of
the hydrogen 1,4-cyclohexanedicarboxylate ranged from 1.202(8)
distance of 3.611 Å, CH3–p interaction between the 3-CH3 of the
pyrazole in the dinuclear unit and the aromatic ring of the pyrazole
in the mononuclear unit with C–Cg distance of 3.671 Å, CH–O
interaction between the CH of the 1,4-cyclohexane moiety and
the OH group of the COOH moiety with C–O distance of 3.431 Å,
CH3–O interaction between the 5-CH3 of the pyrazole in the dinu-
clear unit and the C@O of the hydrogen 1,4-cyclohexanedicarboxy-
late with C–O distance of 3.492 Å, N–HÁ Á ÁO hydrogen bond
between the NH group of the pyrazole and the C@O group that is
involved in CH3–O interaction with N–O distance of 2.991(8) Å,
and O–HÁ Á ÁO hydrogen bond between the OH unit of the COOH
group and one coordinated O atom of the carboxylate with O–O
distance of 2.530(7) Å. The 1D chains were joined together by the
water molecules to form 2D sheet extending at the direction that
made an angle of 45° with the ac plane (Fig. 10). Herein the water
molecules act as bisunidentate donor forming O–HÁ Á ÁO hydrogen
bonds with the unbonded O atom of the mononuclear units and
the unbonded O atom in the dinuclear unit with O–O separations
of 2.858(9)–2.877(10) Å. The 2D sheets were further stacked along
to 1.320(8) Å with the
of the monodentate coordinated COOÀ group of the anion ranged
from 1.239(9) (O(3)–C(2)) to 1.268(8) Å (O(4)–C(2)) with the va-
D value of 0.118 Å. The C–O bond lengths
D
lue of 0.029 Å. The C–O bond lengths of the bischelating coordi-
nated COOÀ group of the anion ranged from 1.243(8) (O(1)–C(1))
to 1.272(8) Å (O(2)–C(1)) with the average value of 1.257 Å. The
difference in bond lengths between the pair of C–O bonds in the
carboxyl group is expected for unionized COOH group. And the dif-
ferences in bond lengths between the two pairs of C–O bonds in
the COOÀ groups agree well with the
D values in the deprotonated
Fig. 10. Packing diagram of compound 5 with 2D sheet structure extending at the direction that made an angle of 45° with the ac plane.

S. Jin, D. Wang / Inorganica Chimica Acta 415 (2014) 31–43
41
carboxylate (C10–O3–O4) of the anion was rotated out of the plane
defined by the remaining part (O1, O2, C1, C2, C3, C4, C5, C6, C7,
and C8) of the dicarboxylate. The pyrazoles were attached to the
chain via the Zn–N coordination bonds. The pair of pyrazoles coor-
dinated to the same Zn is almost perpendicular to each other.
There are also intramolecular N–HÁ Á ÁO hydrogen bonds produced
between the NH group of the pyrazole and the non-bonded O atom
of the carboxylate with N–O distances of 2.692(5)–2.704(5) Å. In
the anion there are found intramolecular CH2–O associations be-
tween the CH2 spacers of the anion and the uncoordinated O atom
of the anion with C–O distances of 2.815–3.248 Å. Thus one of the
unbonded O atoms of the anion acted as a triple acceptor, while the
other uncoordinated O atom in the same anion only functioned as a
single acceptor. Neighboring chains were joined together via the
interchain CH3–O association between the 5-CH3 of the pyrazole
and the coordinated O atom with C–O distance of 3.289 Å to form
2D grid sheet extending along the ab plane (Fig. 12). Herein one
pyrazole is at the plane defined by the sheet, while another pyra-
zole is protruded from the sheet plane. Two adjacent sheets were
held together by the CH3–O association between the 3-CH3 of the
pyrazole and the uncoordinated O atom of the anion with C–O dis-
tance of 3.476 Å to form 2D double sheet structure. The chains of
the second sheet were located at the center of the grid at the first
sheet. In this regard the pyrazoles at the double sheets that are
protruded from the sheet plane are oppositely arranged, i.e. one
kind of pyrazole is protruded above the sheet plane that it is at-
tached, while another kind of pyrazole is protruded below the
sheet plane that it is attached. The double sheets were further
stacked along the c axis direction to form 3D layer network struc-
ture. It is worth pointing out that neighboring double sheets ap-
pear to have sled away from each other along the a and b axis
direction.
Fig. 11. Molecular structure of complex 6 showing the atomic numbering scheme
at 30% ellipsoid probability level.
the direction that is perpendicular with its extending direction via
the CH3–p interaction between the 5-CH3 of the pyrazole in the
mononuclear unit and the aromatic ring of the pyrazole in the
dinuclear unit with C–Cg distance of 3.349 Å, CH3–O contact be-
tween the 5-CH3 of the pyrazole in the dinuclear unit and the car-
bonyl group of the mononuclear unit with C–O distance of 3.498 Å
to form 3D network structure.
3.2.6. Crystal and molecular structure of Zn(Hdmpz)2(L6) (6)
Compound 6 of the formula Zn(Hdmpz)2(L6) crystallizes in the
monoclinic space group P21/c, and there are 4 formula units in its
cell content. Each zinc ion is tetrahedrally coordinated by two oxy-
gen atoms of two monodentate L6 ligands, and two nitrogen
atoms, belonging to two different monodentate pyrazole ligands
(Fig. 11). Here the L6 acts as a bismonodentate ligand. The molec-
ular structure of 6 resembles the compounds 2 and 3, except that
here the dicarboxylate substituted the monocarboxylates in 2
and 3.
3.3. Thermogravimetry (TG)
For 1, the first weight loss of 34.67% (Calcd. 34.98%) corresponds
to the loss of both Hdmpz molecules in the temperature range of
174.6–266.6 °C, and the second weight loss of 44.32% between
The Zn and the dicarboxylate were linked alternatively to form
a 1D chain running along the a axis direction. Herein one
Fig. 12. 2D grid sheet structure of compound 6 produced via CH3–O associations.

42
S. Jin, D. Wang / Inorganica Chimica Acta 415 (2014) 31–43
274.2 and 321.4 °C arises from the loss of the two L1 ligands (Calcd.
44.45%). For 2, the weight loss of 28.06% (Calcd. 28.15%) corre-
sponding to the loss of two Hdmpz molecules was observed in
the temperature range of 171.3–283.5 °C, and there was a weight
loss of 62.16% between 297.6 and 476.8 °C which is due to the loss
of the two carboxylate ligands (Calcd. 62.23%). The TGA studies
showed that 3 is stable below 150 °C. Its decomposition begins at
159.6 °C. The weight loss of 29.89% in the temperature range of
159.6–251.3 °C is caused by the loss of the two pyrazole molecules
(Calcd. 30.09%). The weight loss of 59.42% from 258.5 to 416.7 °C is
due to the loss of two L3 ligands (Calcd. 59.56%). For 4, the first
weight loss stage occurs between 161.0 and 250.0 °C and corre-
sponds to the removal of 4 mol of Hdmpz ligands (calcd.: 45.71%,
found: 45.63%). The second stage between 267.0 and 423.0 °C is
accompanied by a mass loss of 40.78% for two 5-chlorosalicylates
(calcd.: 40.83%). For 5, the weight loss of 1.69% in the temperature
range of 78.5–83.6 °C was attributed to the liberation of both lat-
tice water molecules (calcd.: 1.78%), the weight loss of 47.51% in
the temperature of 186.1–276.5 °C is caused by the loss of the
ten Hdmpz ligands (calcd.: 47.59%), all of the HL5 and L5 were re-
moved at the temperature range of 283.0–478.0 °C (Calcd. 33.84%,
found 33.77%). Complex 6 experiences the first weight loss of
41.85% in the temperature range of 166.6–255.9 °C which is due
to the loss of the pyrazole molecules (Calcd. 41.93%). The second
weight loss of 43.74% was observed between 279.4 and 431.8 °C
which was attributed to the loss of the bonded carboxylate ligands
(Calcd. 43.90%).
Appendix A. Supplementary material
CCDC 867488 for 1, 866455 for 2, 866456 for 3, 841385 for 4,
866462 for 5, and 852746 for 6 contain the supplementary crystal-
lographic data for this paper. These data can be obtained free of
charge from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif. Supplementary data associ-
ated with this article can be found, in the online version, at http://
dx.doi.org/10.1016/j.ica.2014.02.027.
References
[1] J.M. Lehn, Supramolecular Chemistry: Concepts and Perspectives, VCH,
Weinheim, 1995.
[2] See, for example: (a) A.M. Kutasi, D.R. Turner, P. Jensen, B. Moubaraki, S.R.
Batten, K.S. Murray, CrystEngComm 11 (2009) 2089;
(b) J.A. Hoshiko, G.B. Wang, J.W. Ziller, G.T. Yee, A.F. Heyduk, Dalton Trans.
(2008) 5712;
(c) J.Y. Zhang, Y. Ma, A.L. Cheng, Q. Yue, Q. Sun, E.Q. Gao, Dalton Trans. (2008)
2061;
(d) C. Janiak, J.K. Vieth, New J. Chem. 34 (2010) 2366;
(e) J.P. Zou, G.W. Zhou, X. Zhang, M.S. Wang, Y.B. Lu, W.W. Zhou, Z.J. Zhang, G.C.
Guo, J.S. Huang, CrystEngComm 11 (2009) 972;
(f) O.M. Yaghi, M. O’Keeffe, N.W. Ockwig, H.K. Chae, M. Eddaoudi, J. Kim, Nature
423 (2003) 705;
(g) G. Férey, Chem. Soc. Rev. 37 (2008) 191;
(h) X.Q. Zhao, P. Cui, B. Zhao, W. Shi, P. Cheng, Dalton Trans. 40 (2011) 805.
[3] C. Janiak, J. Chem. Soc., Dalton Trans. (2001) 2781.
[4] R.L. Rardin, W.B. Tolman, S.J. Lippard, New J. Chem. 15 (1991) 417.
[5] H. Adams, S. Clunas, D.E. Fenton, S.E. Spey, Dalton Trans. (2002) 441.
[6] J. Kuzelka, J.R. Farrell, S.J. Lippard, Inorg. Chem. 42 (2003) 8652.
[7] Y. Tshuva, S.J. Lippard, Chem. Rev. 104 (2004) 987.
[8] A. Salifoglou, Coord. Chem. Rev. 228 (2002) 297.
[9] P. Lemoine, B. Viossat, G. Morgant, F.T. Greenaway, A. Tomas, N.H. Dung, R.J.
Sorenson, J. Inorg. Biochem. 89 (2002) 18.
[10] (a) C. Policar, F. Lambert, M. Cesario, I. Morgenstern-Badarau, Eur. J. Inorg.
Chem. (1999) 2201;
4. Summary
In summary, use of 3,5-dimethylpyrazole and different carbox-
ylate ligands afforded a series of mononuclear to trinuclear diva-
lent metal complexes. Although synthesized by the same
method, they showed different structures ranging from 2D sheet,
3D network, to 3D layer network structure. The central metal ions
are coordinated in N4O2, N2O2, and N3O3 fashions. A distorted octa-
hedral geometry in the case of Cd, and tetrahedral geometry for Zn
were observed in the X-ray studies. It indicated that the geometry
of the coordination metal complexes is determined not only by the
coordination environment but also by the metal entity itself.
Crystallographic studies demonstrated that in these complexes,
the metal centers are coordinated by 3,5-dimethylpyrazole, and
there are no deprotonated 3,5-dimethylpyrazole anions. In addi-
tion, every carboxylate group acts as monodentate ligand toward
the metal ion except the carboxylate in 5. In 5, there existed COOH
and COOÀ groups simultaneously, and the COOÀ coordinated to the
metal in both monodentate and chelating bidentate fashion. The
strong structural propensity toward tetracoordination in Zn com-
pounds seems to disfavour the formation of ‘paddlewheel’ dimeric
complexes [30,37]. The nonbonded O atoms of the carboxylates in
all compounds except 3 are involved in the formation of the intra-
molecular hydrogen bonds with the N–H group of the 3,5-
dimethylpyrazole.
(b) P.R. Levstein, R. Calvo, Inorg. Chem. 29 (1990) 1581;
(c) E. Colacio, J.M. Dominguez-Vera, R. Kivekäs, J.M. Moreno, A. Romerosa, J.
Ruiz, Inorg. Chim. Acta 212 (1993) 115;
(d) J.M. Rueff, N. Masciocchi, P. Rabu, A. Sironi, A. Skoulios, Eur. J. Inorg. Chem.
(2001) 2843;
(e) R.L. Rardin, A. Bino, P. Poganiuch, W.B. Tolman, S. Liu, S.J. Lippard, Angew.
Chem., Int. Ed. Engl. 129 (1990) 812.
[11] Y.H. Xing, Y.H. Zhang, Z. Sun, L. Ye, Y.T. Xu, M.F. Ge, B.L. Zhang, S.Y. Niu, J. Inorg.
Biochem. 101 (2007) 36.
[12] L.M.R. Hill, M.K. Taylor, V.W. Lin Ng, C.G. Young, Inorg. Chem. 47 (2008) 1044.
[13] K. Umakoshi, T. Kojima, K. Saito, S. Akatsu, M. Onishi, S. Ishizaka, N. Kitamura,
Y. Nakao, S. Sakaki, Y. Ozawa, Inorg. Chem. 47 (2008) 5033.
[14] B. Machura, M. Jaworska, R. Kruszynski, Polyhedron 23 (2004) 2523.
[15] Y.J. Sun, B. Zhao, P. Cheng, Inorg. Chem. Commun. 10 (2007) 583.
[16] (a) A.A. Mohamed, S. Ricci, A. Burini, R. Galassi, C. Santini, G.M. Chiarella, D.Y.
Melgarejo, J.P. Fackler Jr., Inorg. Chem. 50 (2011) 1014;
(b) R. Mukheerjee, Coord. Chem. Rev. 203 (2000) 151;
(c) K. Umakoshi, Y. Yamauchi, K. Nakamiya, T. Kojima, M. Yamasaki, H.
Kawano, M. Onishi, Inorg. Chem. 42 (2003) 3907.
[17] (a) J.E. Cosgriff, G.B. Deacon, Angew. Chem., Int. Ed. Engl. 37 (1998) 286;
(b) G.B. Deacon, E.E. Delbridge, B.W. Skelton, A.H. White, Angew. Chem., Int.
Ed. Engl. 37 (1998) 2251;
(c) G.B. Deacon, C.M. Forsyth, A. Gitlits, R. Harika, P.C. Junk, B.W. Skelton, A.H.
White, Angew. Chem., Int. Ed. Engl. 41 (2002) 3249;
(d) I.A. Guzei, A.G. Baboul, G.P.A. Yap, A.L. Rheingold, H.B. Schlegel, C.H. Winter,
J. Am. Chem. Soc. 119 (1997) 3387;
(e) D. Pfeiffer, M.J. Heeg, C.H. Winter, Inorg. Chem. 39 (2000) 2377.
[18] J.R. Perera, M.J. Heeg, H.B. Schlegel, C.H. Winter, J. Am. Chem. Soc. 121 (1999)
4536.
[19] (a) A. Cingolani, S. Galli, N. Masciocchi, L. Pandolf, C. Pettinari, A. Sironi, Dalton
Trans. (2006) 2479;
Complexes 1–6 have abundant intra- and intermolecular weak
non-covalent interactions (including classical hydrogen bonds,
(b) R. Sarma, D. Kalita, J.B. Baruah, Dalton Trans. (2009) 7428;
(c) U.P. Singh, P. Tyagi, S. Pal, Inorg. Chim. Acta 362 (2009) 4403;
(d) J. Li, J.H. Zhou, Y.Z. Li, L.H. Weng, X.T. Chen, Z. Yu, Z. Xue, Inorg. Chem.
Commun. 7 (2004) 538.
ClÁ Á ÁO, C–HÁ Á ÁO, CH2Á Á ÁO, CH3Á Á ÁO, C–HÁ Á Á
p, CH3–p, and p–p inter-
actions) in their crystals, which lead to the formation and stabiliza-
[20] (a) S.W. Jin, D.Q. Wang, Z. Anorg. Allg. Chem. 637 (2011) 618;
(b) S.W. Jin, D.Q. Wang, J. Coord. Chem. 64 (2011) 1940.
[21] (a) P. Metrangolo, H. Neukirch, T. Pilati, G. Resnati, Acc. Chem. Res. 47 (2005)
386;
tion of the final structures.
Acknowledgements
(b) T.R. Shattock, K.K. Arora, P. Vishweshwar, M.J. Zaworotko, Cryst. Growth
Des. 8 (2008) 4533;
(c) K. Biradha, G. Mahata, Cryst. Growth Des. 5 (2005) 61;
(d) B.Q. Ma, P. Coppens, Chem. Commun. (2003) 504;
(e) D.J. Berry, C.C. Seaton, W. Clegg, R.W. Harrington, S.J. Coles, P.N. Horton,
We gratefully acknowledge the financial support of the Educa-
tion Office Foundation of Zhejiang Province (project No.
Y201017321) and the financial support of the Xinmiao project of
the Education Office Foundation of Zhejiang Province.
´
M.B. Hursthouse, R. Storey, W. Jones, T. Frisꢁcꢁic, N. Blagden, Cryst. Growth Des.
8 (2008) 1697;

S. Jin, D. Wang / Inorganica Chimica Acta 415 (2014) 31–43
43
(f) L. Fa´bia´n, N. Hamill, K.S. Eccles, H.A. Moynihan, A.R. Maguire, L.
McCausland, S.E. Lawrence, Cryst. Growth Des. 11 (2011) 3522.
[22] Bruker, SMART and SAINT, Bruker AXS Inc., Madison, WI, USA, 2004.
[23] SHELXTL-PC, version 5.03, Siemens Analytical Instruments, Madison, WI, 1994.
[24] Y.P. Wu, D.S. Li, F. Fu, W.W. Dong, L. Tang, Y.Y. Wang, Inorg. Chem. Commun.
13 (2010) 1005.
[30] B. Singh, J.R. Long, F. Fabrizi de Biani, D. Gatteschi, P. Stavropoulos, J. Am.
Chem. Soc. 119 (1997) 7030.
[31] J. Bernstein, R.E. Davis, L. Shimoni, N.L. Chang, Angew. Chem., Int. Ed. 34 (1995)
1555.
[32] K.M. Lo, S.W. Ng, Acta Crystallogr., Sect. E 65 (2009) o1101.
[33] M. Sundaralingam, L.H. Jensen, Acta Crystallogr. 18 (1965) 1053.
[34] G. Simith, A.W. Hartono, U.D. Wermuth, P.C. Healy, J.M. White, A.D. Rae, Aust. J.
Chem. 58 (2005) 47.
[25] Y.J. Sun, P. Chen, S.P. Yan, D.Z. Liao, Z.H. Jiang, P.W. Shen, J. Coord. Chem. 55
(2002) 363.
[26] J.Y. Lu, E.E. Kohler, Inorg. Chem. Commun. 5 (2002) 600.
[27] J. Li, Y.H. Xing, H.Y. Zhao, Z.P. Li, C. Guang Wang, X.Q. Zeng, M.F. Ge, S.Y. Niu,
Inorg. Chim. Acta 362 (2009) 2788.
[28] K. Bania, N. Barooah, J.B. Baruah, Polyhedron 26 (2007) 2612.
[29] X.M. Chen, Z.T. Xu, X.C. Huang, J. Chem. Soc., Dalton Trans. (1994) 2331.
[35] Y. Yang, P. Du, J.F. Ma, W.Q. Kan, B. Liu, J. Yang, Cryst. Growth Des. 11 (2011)
5540.
[36] M. Kubicki, P. Wagner, Acta Crystallogr., Sect. C 63 (2007) o454.
[37] H.L. Chun, D.N. Dybtsev, H. Kin, K. Kim, Chem. Eur. J. 11 (2005) 3521. and
references cited therein.