Syntheses and structures of d9 and d10 metal complexes with 2,3,5-pyridinetricarboxylic acid

Article abstract of DOI:10.1016/j.molstruc.2006.05.049

Three complexes with different structures were obtained by reacting 2,3,5-pyridinetricarboxylic acid (H₃pta) with d⁹ (Cu²⁺) and d¹⁰ (Zn²⁺, Ag⁺) ions in water at room temperature. The complexes of [Cu(H₂pta)₂(H₂O)₂]·2H₂O (1) and [Zn₂(Hpta)₂(H₂O)₆]·4H₂O (2) are mononuclear and binuclear structures, respectively; while [Ag(H₂pta)(H₂O)]_n (3) is a helical 1D chain coordination polymer. A double chain was further formed in 3 by the weak interaction between oxygen atoms and Ag(I) ions. Through hydrogen bonds the three complexes constructed corresponding 3D network structures. The three complexes were characterized by elemental analyses, IR and single-crystal X-ray diffraction analyses. In addition, TGA, XRD and fluorescence spectra determinations were performed for compounds 2 and 3.

Full text of DOI:10.1016/j.molstruc.2006.05.049

Journal of Molecular Structure 829 (2007) 1–7
www.elsevier.com/locate/molstruc
Syntheses and structures of d 9 and d10 metal complexes
with 2,3,5-pyridinetricarboxylic acid
Hongsheng Wang, Jiangong Ma, Bin Zhai, Yuanyuan Liu, Peng Cheng ¤
Department of Chemistry, Nankai University, Tianjin 300071, PR China
Received 3 March 2006; received in revised form 25 May 2006; accepted 30 May 2006
Available online 17 July 2006
Abstract
Three complexes with diVerent structures were obtained by reacting 2,3,5-pyridinetricarboxylic acid (H3pta) with d9 (Cu2+) and d10
(Zn2+,Ag+) ions in water at room temperature. The complexes of [Cu(H2pta)2(H2O)2]·2H2O (1) and [Zn2(Hpta)2(H2O)6]·4H2O (2) are
mononuclear and binuclear structures, respectively; while [Ag(H2pta)(H2O)]n (3) is a helical 1D chain coordination polymer. A double
chain was further formed in 3 by the weak interaction between oxygen atoms and Ag(I) ions. Through hydrogen bonds the three complexes
constructed corresponding 3D network structures. The three complexes were characterized by elemental analyses, IR and single-crystal X-
ray diVraction analyses. In addition, TGA, XRD and Xuorescence spectra determinations were performed for compounds 2 and 3.
© 2006 Elsevier B.V. All rights reserved.
Keywords: 2,3,5-Pyridinetricarboxylic acid; Copper(II) complex; Zinc(II) complex; Silver(I) complex; Crystal structure
1. Introduction
2. Experimental section
The design and synthesis of metal organic framework
(MOF) with diVerent pyridinedicarboxylic acid is of intense
interest such as 2,6-pyridinedicarboxylic acid [1], 2,5-pyrid-
inedicarboxylic acid [2], 3,5-pyridinedicarboxylic acid [3],
3,4-pyridinedicarboxylic acid [4], and so on. The complexes
with these organic multicarboxylate ligands have potential
application in molecular sieve, optoelectronics, magnetism
and chem-sensors. Compared with pyridinedicarboxylic
acid, the pyridinetricarboxylic acid has more coordination
sites and some novel structures and coordination modes are
desired to be obtained, but was much less used so far. Sev-
eral examples on 2,4,6-pyridinetricarboxylic acid have been
reported by our group [5] and others [6]. Here we report
three 2,3,5-pyridinetricarboxylic acid (H3pta) coordination
compounds. And to our knowledge, the single crystal struc-
tures of complexes with 2,3,5-pyridinetricarboxylic acid
have never been reported before.
2.1. Materials and methods
2,3,5-Pyridinetricarboxylic acid was synthesized by
oxidation of 2,3,5-trimethylpyridine with potassium
permanganate. The perchlorates were obtained by reacting
perchlorate acid with the corresponding metal oxides.
Elemental analyses were performed in a Perkin-Elmer 240
analyzer. IR spectra were recorded with a Tensor 27 FTIR
spectrophotometer (KBr pellet, range from 4000 to
400cm¡1). TGA was performed on a Thermogravimetric-
DiVerential thermal analyzer (standard type). The Xuores-
cence spectra were determined on a Cary Eclipse Xuorescence
spectrophotometer. The X-ray diVraction data were collected
in a Bruker SMART 1000 CCD and a Bruker SMART
APEX II CCD area detector. The XRD patterns were
determined on a D/Max-2500 X-ray diVractometer.
2.2. Preparations of the complexes
*
[Cu(H2pta)2(H2O)2] · 2H2O:
Cu(ClO4)2·6H2O
and
Corresponding author. Fax.: +862223502458.
H3pta in molar ratio of 1.5:1 with addition of Wve drops
E-mail address: pcheng@nankai.edu.cn (P. Cheng).
0022-2860/$ - see front matter © 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.molstruc.2006.05.049

2
H. Wang et al. / Journal of Molecular Structure 829 (2007) 1–7
Table 1
Crystallographic data for 1–3
1736, 1619, 1585, 1466, 1373, 1306, 1269, 1161, 840, 795,
693, 536.
[Zn2(Hpta)2(H2O)6] · 4H2O: Zn(ClO4)2·6H2O and H3pta
1
2
3
in molar ratio of 1:1 in 30 mL water at room temperature,
Wltered after stirring for 1 h, the solution was allowed to
stand for about 2 months, colorless block crystalline
Empirical formula C16H16CuN2O16 C16H26N2O22Zn2 C8H6AgNO7
M
T (K)
ꢀ (Å)
555.85
293(2)
729.12
293(2)
0.71073
336.01
294(2)
0.71073
0.71073
obtained
in
42%
yield.
Anal.
Calcd
for
Cryst system
Space group
a (Å)
b (Å)
c (Å)
Monoclinic
P2(1)/n
5.481(4)
14.980(11)
12.400(9) A
90
98.166(9)
90
1007.8(13)
2
Triclinic
P-1
Triclinic
P-1
7.5293(15)
8.0461(16)
8.6034(17)
77.685(3)
73.330(3)
73.928(3)
474.69(16)
2
C16H26N2O22Zn2(%): C, 26.36; H, 3.59; N, 3.84. Found (%):
C, 25.82; H, 3.99; N, 3.58. IR(KBr, cm¡1): 3418, 1698, 1635,
1582, 1450, 1361, 1294, 1276, 1237, 1164, 1095,951, 846, 811,
773, 733,703,615, 575, 531.
7.905(7)
8.264(7)
10.176(8)
77.944(11)
83.475(10)
72.819(10)
620.1(9)
2
ꢁ (°)
ꢂ (°)
[Ag(H2pta)(H2O)]n: AgNO3 and H3pta in molar ratio of
2:1 with addition of 10 drops perchlorate acid (3 molL¡1
)
ꢃ (°)
V (Å3)
Z
in 30 mL water at room temperature, Wltered after stirring
for 1 h, the solution was allowed to stand for about 2 weeks,
colorless block crystalline obtained in 53% yield. Anal.
Calcd for C8H6AgNO7(%): C, 28.60; H, 1.80; N, 4.17.
Found (%): C, 28.20; H, 2.45; N, 4.16. IR(KBr, cm¡1): 3499,
3441, 1683, 1622, 1432, 1396, 1285, 1085, 777, 710, 516.
ꢄ (mm¡1
)
1.177
2.044
2.150
R1 [I > 2ꢅ (I)]
0.0304
0.0943
0.0385
wR2
0.0891
0.2162
0.1066
perchlorate acid (3 mol L¡1) in 30 mL water at room tem-
perature, Wltered after stirring for 1 h, the solution was
allowed to stand for about 3 weeks, blue crystalline prod-
uct can be obtained in yield of 34%. Anal. Calcd for
C16H16CuN2O16(%): C, 34.57; H, 2.90; N, 5.04. Found (%):
C, 34.99; H, 2.70; N, 5.08. IR(KBr, cm¡1): 3617, 3445,
2.3. X-ray structure determination
X-ray diVraction data of 1 were collected with a Bru-
ker SMART 1000 CCD area detector, and data of 2 and
3 with a Bruker SMART APEX II CCD area detector.
Table 2
Selected bond lengths (Å) and angles (°) for 1–3
Compound 1
Cu(1)AO(1)
Cu(1)AO(1)#1
Cu(1)AN(1)#1
1.9723(18)
1.9723(18)
1.997(2)
Cu(1)AN(1)
Cu(1)AO(7)
Cu(1)AO(7)#1
O(1)ACu(1)AN(1)#1
O(1)ACu(1)AN(1)
N(1)#1ACu(1)AN(1)
O(1)#1ACu(1)AO(7)
N(1)ACu(1)AO(7)
O(1)#1ACu(1)AO(7)#1
N(1)ACu(1)AO(7)#1
1.997(2)
2.384(2)
2.384(2)
97.60(8)
82.40(8)
180.00(6)
87.96(8)
91.06(8)
92.04(8)
88.94(8)
O(1)ACu(1)AO(1)#1
O(1)#1ACu(1)AN(1)#1
O(1)#1ACu(1)AN(1)
O(1)ACu(1)AO(7)
N(1)#1ACu(1)AO(7)
O(1)ACu(1)AO(7)#1
N(1)#1ACu(1)AO(7)#1
O(7)ACu(1)AO(7)#1
180.00(9)
82.40(8)
97.60(8)
92.04(8)
88.94(8)
87.96(8)
91.06(8)
180.000(1)
Compound 2
Zn(1)AO(8)
Zn(1)AO(3)#1
Zn(1)AO(1)
2.052(6)
2.089(7)
2.126(6)
98.2(3)
Zn(1)AO(9)
Zn(1)AN(1)
Zn(1)AO(7)
O(8)AZn(1)AO(3)#1
O(8)AZn(1)AN(1)
O(3)#1AZn(1)AN(1)
O(9)AZn(1)AO(1)
N(1)AZn(1)AO(1)
O(9)AZn(1)AO(7)
N(1)AZn(1)AO(7)
2.073(6)
2.105(7)
2.220(6)
85.2(3)
95.5(3)
100.3(3)
89.1(2)
76.5(2)
84.7(3)
87.7(3)
O(8)AZn(1)AO(9)
O(9)AZn(1)AO(3)#1
O(9)AZn(1)AN(1)
O(8)AZn(1)AO(1)
O(3)#1AZn(1)AO(1)
O(8)AZn(1)AO(7)
O(3)#1AZn(1)AO(7)
O(1)AZn(1)AO(7)
89.7(3)
163.7(3)
170.8(2)
100.4(2)
85.1(3)
168.1(2)
90.1(3)
Compound 3
Ag(1)AO(7)
Ag(1)AO(4)#1
2.308(3)
2.431(3)
Ag(1)AN(1)
Ag(1)AO(1)
2.324(3)
2.554(3)
O(7)AAg(1)AN(1)
N(1)AAg(1)AO(4)#1
N(1)AAg(1)AO(1)
C(4)AO(4)AAg(1)#2
136.75(12)
97.49(12)
67.99(10)
134.7(3)
O(7)AAg(1)AO(4)#1
O(7)AAg(1)AO(1)
O(4)#1AAg(1)AO(1)
115.95(13)
86.52(11)
155.92(12)
Symmetry transformations used to generate equivalent atoms for 1–3.
1: #1 ¡x, ¡y + 1, ¡z + 1. 2: #1 ¡x + 1, ¡y + 2, ¡z. 3: #1 x, y ¡ 1, z; #2 x, y + 1, z.

H. Wang et al. / Journal of Molecular Structure 829 (2007) 1–7
3
Table 3
H-bonds in the three complexes
DAH
d (DAH) (Å)
d (H,A) (Å)
\DHA (°)
d (D,A) (Å)
A
Compound 1
O3AH3
O5AH5
O7AH7A
O7AH7B
O8AH8A
O8AH8B
0.820
0.820
0.850
0.850
0.851
0.851
1.827
1.794
2.631
2.014
2.385
1.936
157.44
176.13
126.10
161.64
112.72
174.40
2.604
2.613
3.207
2.833
2.825
2.784
O8 [x ¡ 1, y, z]
O2 [x + 3/2, ¡y + 3/2, z + 1/2]
O4 [x + 1/2, ¡y + 3/2, z ¡ 1/2]
O1 [x + 1, y, z]
O4 [¡x, ¡y + 2, ¡z + 1]
O6 [x ¡ 1/2, ¡y + 3/2, z ¡ 1/2]
Compound 2
O5AH5
O7AH7A
O7AH7B
O8AH8A
O8AH8B
O9AH9A
O9AH9B
0.820
0.850
0.850
0.852
0.884
0.850
0.850
0.850
0.850
0.852
0.852
0.850
0.850
0.850
0.850
1.741
2.062
2.134
1.911
2.222
1.897
2.064
2.647
1.962
2.020
2.226
2.352
2.372
2.064
2.585
162.62
168.29
169.55
159.88
113.48
177.37
166.90
114.28
162.14
136.03
136.04
126.92
147.78
162.83
119.72
2.536
2.900
2.974
2.727
2.698
2.747
2.898
3.096
2.784
2.698
2.900
2.942
3.124
2.887
3.096
O1 [x + 1, y ¡ 1, z]
O10
O2 [¡x, ¡y + 2, ¡z]
O4 [x, y, z + 1]
O10
O6 [x ¡ 1, y + 1, z]
O9 [¡x, ¡y + 2, ¡z + 1]
O11 [x, y + 1, z]
O11
O9AH9B
O10AH10A
O10AH10B
O10AH10B
O11AH11A
O11AH11A
O11AH11B
O11AH11B
O8
O7
O2 [x, y ¡ 1, z + 1]
O3 [x, y ¡ 1, z + 1]
O3 [¡x + 1, ¡y + 1, ¡z]
O9 [x, y ¡ 1, z]
Compound 3
O7AH7A
O7AH7B
O5AH5A
O3AH3A
0.848
0.851
0.849
0.851
2.023
2.093
1.692
1.773
169.13
157.57
169.03
164.18
2.860
2.898
2.530
2.602
O6 [¡x + 2, ¡y + 1, ¡z + 2]
O6 [x ¡ 1, y, z + 1]
O1 [x + 1, y, z ¡ 1]
O2 [¡x + 1, ¡y + 3, ¡z + 2]
The two detectors were both equipped with a Mo X-ray
tube and a graphite monochromator. All calculations
were carried out with the SHELXTL-97 programs. Struc-
tures were solved by direct methods. All non-hydrogen
atoms were reWned anisotropically. All hydrogen atoms
were located and reWned isotropically. Three block crys-
tals of 1, 2 and 3 with the dimensions of 0.26 £ 0.14 £ 0.10
(1), 0.22 £ 0.10 £ 0.10 (2) and 0.20 £ 0.14 £ 0.12 (3) mm3
were used, respectively.
Crystallographic data for the three compounds are listed
in Table 1 and the selected bond lengths and angles are
listed in Table 2. The hydrogen bonds data are listed in
Table 3.
3. Results and discussion
3.1. Crystal structures of complexes
Compound
1
showed
a mononuclear structure
(Fig. 1a). Cu(II) ion octahedrally coordinated with two
[H2pta¡] by two oxygen atoms and two nitrogen atoms in
the plane and two water molecules at the axis. The oxy-
gen atoms and nitrogen atoms in the plane are trans to
each other (Cu(1)AO(1) 1.9723(18) Å, Cu(1)AO(1)A
1.9723(18) Å, Cu(1)AN(1) 1.997(2) Å, Cu(1)AN(1)
1.997(2) Å). The plane is approximately a square. The
CuAO bond length at axis is 2.384(2) Å. Bond angles of
OACuAN range from 82.40(8)° to 97.60(8)°, OACuAO
Fig. 1. (a) X-ray single structure of 1; (b) 3D structure of 1 constructed by
hydrogen bonds. All the hydrogen atoms have been omitted for clarity.

4
H. Wang et al. / Journal of Molecular Structure 829 (2007) 1–7
Fig. 2. (a) X-ray single structure for 2; (b) 3D structure for 2 constructed
by hydrogen bonds.
Fig. 3. (a) X-ray single structure of 3; (b) 1D chain structure for 3; (c) the
helical structure for 3.
from 87.96(8)° to 180.00(9)°, and NACuAN is almost
180°. The whole molecular structure is nearly an
octahedron. There are two free carboxyl groups, two
coordinated water and two lattice water molecules in 1,
and a 3D supermolecule has been constructed by the
hydrogen bonds between the carboxyl groups and water
molecules (Fig. 1b). For 1, only one of the three carboxyl
groups in each ligand coordinates with Cu(II) ion, which
indicates that addition of acid can restrain the ionization
of H3pta in water eVectively. Therefore, it is diYcult to
obtain high dimensional coordination polymer under
such conditions.
Complex 2 showed a binuclear structure (Fig. 2a).
Each Zn(II) center octahedrally coordinated with two
[Hpta2¡] ligands and three water molecules. [Hpta2¡] che-
lated to Zn(II) ion by oxygen atom of 2-carboxyl group
and nitrogen atom (Zn(1)AO(1) 2.126(6) Å, Zn(1)AN(1)
2.105(7) Å), while the bond lengths between three water
molecules and Zn(II) center are 2.220(6) Å (Zn(1)AO(7)),
2.052(6) Å (Zn(1)AO(8)), and 2.073(6) Å (Zn(1)AO(9)),
and the 3-carboxyl group bonded to the other Zn(II) ion
acts as a bridging group (Zn(1)AO(3)A 2.089(7) Å). The
bond angles of OAZnAO range from 84.7(3)° to
170.8(2)°, and NAZnAO from 76.5(2)° to 163.7(3)°. A
single 12-membered macrocycle is formed containing two
[Hpta2¡] and two Zn(II) ions. A 3D network structure is
obtained through the hydrogen bonds between water
molecules and carboxyl groups, as shown in Fig. 2b.
The X-ray crystal structure of 3 was shown in Fig. 3a.
A 1D zigzag chain (Fig. 3b) with helix (Fig. 3c) was
obtained. The silver(I) ion was found to be four coordi-
nated. One of the coordination atoms is nitrogen atom
(Ag(1)AN(1) 2.324(3) Å) from the pyridine ring of H3pta,
the other three are oxygen atoms from one water mole-
cule and [H2pta¡] (Ag(1)AO(7) 2.308(3) Å, Ag(1)AO(1)
2.554(3) Å, Ag(1)AO(4)A 2.431(3) Å). The bond angles of
OAAgAN range from 67.99(10)° to 136.75(12)°, OAA-
gAO from 86.52(11)° to 155.92(12)°. In addition, a dou-
ble chain structure (Fig. 4a) is formed by the weak
interaction (dashed line) between one of the oxygen
atoms of 2-carboxyl group in one chain and Ag(I) ions in
the other chain, and the distance of OAAg(I) is 2.861 Å.
The interchain and intrachain minimum distances
between silver ions were 5.712 Å and 8.046 Å. A 3D net-
work structure has been formed through hydrogen bonds
(Fig. 4b).

H. Wang et al. / Journal of Molecular Structure 829 (2007) 1–7
5
Fig. 4. (a) The double chain structure of 3; (b) 3D structure constructed by
hydrogen bonds.
3.2. Coordination modes of the ligand
For the three complexes, two coordination modes of 2,3,5-
pridinetricarboxylic have been found and are shown in
Scheme 1. It is indicated in Scheme 1a that the ligand adopts a
mode chelating to metal ions by 2-carboxyl group together
with nitrogen atom. The carboxyl groups in 3- and 5-positions
did not coordinate to any metal ions (for 1). In Scheme 1b the
2-carboxyl group and nitrogen atom are the same as in
Scheme 1a, while the 3-carboxyl group acted as a monoden-
tate bridge coordinating to another metal ion (for 2 and 3).
3.3. IR spectra of the complexes
In IR spectra of 1 and 3, two strong peaks at 3617cm¡1
for 1 and 3499 cm¡1 for 3 showed there are hydroxyl groups
of protonated carboxylate groups in the two complexes; in
IR spectra of 1 and 2, two peaks at 1736 cm¡1 for 1 and
1698 cm¡1 for 2 indicated that there were protonated car-
boxylate groups [7]. The peaks at 1582 cm¡1 for 1,
1585 cm¡1 for 2 and 1683 cm¡1 for 3 showed that coordi-
nated carboxyl groups existed in the three complexes. All
these are accorded with the results of crystal structures. In
IR spectra of three complexes, the main strong peaks are at
1582 cm¡1 and 1371 cm¡1 for 1, 1585 cm¡1 and 1416 cm¡1
for 2 while 1683cm¡1 and 1396cm¡1 for 3, are correspond-
Fig. 5. XRD patterns for 1 (a) room temperature; (b) calcinated for 4 h at
100 °C; (c) calcinated for 4 h at 180°C.
ing to the asymmetrical and symmetrical stretching vibra-
tions of coordinated carboxyl groups, respectively.
3.4. Thermal analysis and Xuorescence determination
The thermal behaviors of 2 and 3 were observed from
20°C to 600 °C. The results show that 2 lost lattice water
Scheme 1. Two coordination modes of the ligand. (a) For 1; (b) for 2 and 3.

6
H. Wang et al. / Journal of Molecular Structure 829 (2007) 1–7
complexes emit Xuorescence due to the ligand-to-metal
transfer (LMCT) [8]. We have also determined the Xuores-
cence emission of 2 and 3 in solid state at room tempera-
ture. The result showed that both the complexes have no
any emission in visible region. So the ligand is not suitable
for the luminescence of Ag(I) and Zn(II) ions in the
described structures.
3.5. XRD analyses
The XRD patterns have been determined for 2 and 3
after calcination at diVerent temperature, as shown in Fig. 5
and 6, respectively. The results show that the structure of 2
changed after calcination at 100 °C for 4h, and the struc-
ture after calcination at 180 °C for 4 h is similar with that at
100°C. The structure of 3 was collapsed after calcinated at
the temperature of 180 °C.
In summary, Cu(II), Zn(II) and Ag(I) complexes of
2,3,5-pyridinetricarboxylic acid were obtained in water
solution at diVerent acidity. The single crystal structures of
three complexes with 2,3,5-pyridinetricarboxylic acid were
Wrst obtained.
4. Supplementary data
Crystallographic data for the three complexes in this
paper have been deposited at the Cambridge Crystallo-
graphic data centre, CCDC No. 286200 for complex 1,
286199 for complex 2 and 276069 for complex 3. Copies
of this information may be obtained free of charge from
the center, CCDC, 12 Union Road, Cambridge CB2 1EZ,
UK (fax: +44 1223 336 033; e-mail: deposit@ccdc.cam.
ac.uk).
Acknowledgements
This work was supported by the National Natural Sci-
ence Foundation of China (Nos. 20425103 and 90501002)
and the National Key Project for Fundamental Research
(2005CCA01200).
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