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Syntheses, structures and thermal stabilities of four complexes with 4-amino-3,5-bis(3-pyridyl)-1,2,4-triazole ligand
Journal of Molecular Structure 891 (2008) 50–57
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Journal of Molecular Structure journal homepage: www.elsevier.com/locate/molstruc
Syntheses, structures and thermal stabilities of four complexes with 4-amino-3,5-bis(3-pyridyl)-1,2,4-triazole ligand Jing-Jing Liu a, Xiang He a,*, Min Shao b, Ming-Xing Li a,* a b
Department of Chemistry, College of Science, Shanghai University, Shanghai 200444, China Instrumental Analysis and Research Center, Shanghai University, Shanghai 200444, China
a r t i c l e
i n f o
Article history: Received 9 January 2008 Accepted 4 March 2008 Available online 20 March 2008 Keywords: 4-Amino-3,5-bis(3-pyridyl)-1,2,4-triazole Transition metal complex Crystal structure Coordination polymers Thermal analysis
a b s t r a c t Reactions of 4-amino-3,5-bis(3-pyridyl)-1,2,4-triazole (3-abpt) with metal acetates gave rise to four new complexes [Cu(3-abpt)(ip)]n2nH2O (1), [Co(3-abpt)(ip)(H2O)2]n2nH2O (2), [Ni(3-abpt)(tp)(H2O)2]n(3) and [Cu(3-abpt)2(CH3COO)2(H2O)2] (4) (ip = isophthalate, tp = terephthalate), which were characterized by EA, IR and X-ray crystallography. Compound 1 consists of two kinds of ring-like chain which are interconnected to form an unusual two-dimensional layered motif. Compounds 2 and 3 are both 1D ring-like infinite chains. Compound 4 is a mononuclear complex. The thermal stabilities of coordination polymers 1–3 have been investigated. Ó 2008 Elsevier B.V. All rights reserved.
1. Introduction
2. Experimental
Coordination polymers with well-designed shape and functionality have attracted considerable attention recently [1]. Suitable ligands with appropriate coordination sites linked by specific connectors have been proved to be an efficient route for the formation of coordination polymers with desirable structure topologies and potential applications in catalysis, biology and material science [2–6]. Currently, triazole ligands as well as their derivatives, known for their rich coordination modes and wide applications as multidentate bridging ligands in coordination chemistry, are of considerable interesting in constructing coordination polymers [7]. 4Amino-3,5-bis(3-pyridyl)-1,2,4-triazole (3-abpt) can provide three typical conformations (see Scheme 1) under appropriate surroundings, and it can be served as a good candidate for the construction of the molecular cages [8], rings [9], grids [10] and ladders [11]. On the other hand, it is well known that carboxylate ligands, especially isophthalate (ip) and terephthalate (tp), present a high structural effect in assembling coordination polymers due to their numerous possible coordination modes (see Scheme 2) [12–15]. We select CuII, CoII and NiII as metal nodes to obtain four complexes, namely [Cu(3abpt)(ip)]n2nH2O (1), [Co(3-abpt)(ip)(H2O)2]n2nH2O (2), [Ni(3abpt)(tp)(H2O)2]n (3) and [Cu(3-abpt)2(CH3COO)2(H2O)2] (4). Herein, we report their syntheses, structures and thermal stabilities.
2.1. Materials and methods
* Corresponding authors. E-mail addresses: [email protected] (X. He), [email protected] (M.-X. Li). 0022-2860/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.molstruc.2008.03.011
The ligand 4-amino-3,5-bis(3-pyridyl)-1,2,4-triazole was prepared according to the literature method [16]. Other chemicals were of reagent grade and used as purchased without further purification. Elemental analyses (EA) were performed on a Vario EL III analyzer. Infrared spectra (IR) were recorded with a Nicolet A370 FT-IR spectrometer by KBr pellets in the range 400–4000 cm1. Thermogravimetric analyses (TG-DSC) were completed on a Netzsch STA 449C thermal analyzer at a heating rate of 10 °C/min in air. 2.2. Synthesis [Cu(3-abpt)(ip)]n2nH2O (1): a mixture of Cu(OAc)2H2O (0.048 g, 0.24 mmol), 3-abpt (0.048 g, 0.20 mmol), H2ip (0.033 g, 0.20 mmol) and water (16 mL) was sealed in a Teflon-lined stainless steel vessel (25 mL), which was heated at 140 °C for 3 days and then cooled to room temperature at a rate of 10 °C/h. Green rhombus crystals of 1 were collected in 48% yield (0.048 g, based on 3-abpt). Anal. Calcd for C20H18CuN6O6: C, 47.86; H, 3.61; N, 16.74%. Found: C, 48.03; H, 3.61; N, 16.58%. IR (KBr pellet, cm1): 3425m, 3351m, 3174w, 3097w, 1627vs, 1550s, 1441m, 1396s, 1371vs, 823m, 739m, 720s, 694m, 652w. [Co(3-abpt)(ip)(H2O)2]n2nH2O (2): a mixture of Co(OAc)24H2O (0.030 g, 0.12 mmol), 3-abpt (0.024 g, 0.10 mmol), H2ip (0.017 g, 0.10 mmol) and water (10 mL) was sealed in a Teflon-lined stainless steel vessel (15 mL), which was heated at 140 °C for 3
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J.-J. Liu et al. / Journal of Molecular Structure 891 (2008) 50–57 N
N
N
N
M N
N
N
N
NH 2
NH 2
N
N
N
M
M
M
A
N
M
M N
N
N NH 2
B
C
Scheme 1. Three typical conformations presented by 3-abpt.
O
O
O
O
C
C
C
C
O
O
O
O
O
M
A
O
O
B
O
O
M
O C
C
O
O
O
O C
C
M
O
O
M
O
D
O
C
M
M
C
O
O
C
C
O
O
O O
M
M
E
M
M
M
F
M
G
H
O
O C
C
O
O
M
M
O
O C
M
M
C O
O
M
O
O
O
O
O C
O C
O
O
N
O
C MM
M M
O C
C O
O
O
M O
M
O
M
C
O
O
L
C
M
M
C
O
M
O
O
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O C
M
K
O
M
C
O C
G
O C
O
C
I
M
C
M M
O
C
C
C
C
O
O
O
M
M
O
P
O
M
O
M
C
Q
Scheme 2. Possible coordination modes presented by the carboxylate groups of ip and tp.
days and then cooled to room temperature at a rate of 10 °C/h. A clear pink solution was obtained, and the filtrate was left to stand for 3 days at room temperature. Pink prism crystals of 2 were collected in 52% yield (0.028 g, based on 3-abpt). Anal. Calcd for C20H22CoN6O8: C, 45.04; H, 4.16; N, 15.76%. Found: C, 45.29; H, 4.14; N, 15.70%. IR (KBr pellet, cm1): 3352s, 3143s, 1670w, 1599s, 1546vs, 1480m, 1422s, 1373vs, 819w, 761m, 705s. [Ni(3-abpt)(tp)(H2O)2]n (3): an aqueous (10 mL) solution of Ni(OAc)24H2O (0.027 g, 0.11 mmol) was slowly added to a solution of 3-abpt (0.024 g, 0.10 mmol) in ethanol (10 mL) with stirring for 30 min. Then a solution of H2tp (0.017 g, 0.10 mmol) in DMF (5 mL) was added to above mixture with continuous stirring for another 30 min and filtrated. The filtrate was left to stand for 2 weeks at room temperature. Green block crystals of 3 were col-
lected in 36% yield (0.018 g, based on 3-abpt). Anal. Calcd for C20H18NiN6O6: C, 48.32; H, 3.65; N, 16.91%. Found: C, 48.07; H, 3.85; N, 16.64%. IR (KBr pellet, cm1): 3374m, 3200w, 3079w, 1558vs, 1383vs, 1033m, 1018m, 799s, 753s, 699s, 519m. [Cu(3-abpt)2(CH3COO)2(H2O)2] (4): an aqueous (10 mL) solution of Cu(OAc)2H2O (0.040 g, 0.20 mmol) was slowly added to a solution of 3-abpt (0.048 g, 0.2 mmol) in methanol (10 mL). The mixture was stirred for about 20 min and left to stand for 2 weeks at room temperature. Blue block crystals of 4 were obtained in 30% yield (0.042 g, based on 3-abpt). Anal. Calcd for C28H30CuN12O6: C, 48.45; H, 4.36; N, 24.21%. Found: C, 48.35; H, 4.36; N, 23.84%. IR (KBr pellet, cm1): 3336m, 3238m, 3115w, 3015w, 1560vs, 1480w, 1451w, 1410vs, 1340m, 1197w, 1031w, 981m, 821m, 703s, 662w, 624w.
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J.-J. Liu et al. / Journal of Molecular Structure 891 (2008) 50–57
Table 1 Crystal data and structural refinement for compounds 1–4 Compound
1
2
3
4
Formula Formula weight Crystal system Space group a (Å) b (Å) c (Å) a (°) b (°) c (°) V (Å3) Z Dc (g cm3) F(0 0 0) l (mm1) h for data collection (°) Reflections collected Goodness-of-fit on F2 R1, wR2 [I > 2r(I)] R1, wR2 (all data)
C20H18CuN6O6 501.95 Triclinic P1 9.0805 (11) 10.0891 (11) 12.4016 (15) 66.849 (10) 89.442 (10) 79.389 (10) 1024.3 (2) 2 1.621 510 1.119 2.24–27.49 6448 1.097 0.0475, 0.1424 0.0598, 0.1589
C20H22CoN6O8 533.36 Monoclinic P2(1)/c 8.462 (7) 14.457 (12) 19.669 (15) 90 110.76 (3) 90 2250 (3) 4 1.563 1084 0.823 2.57–27.57 11531 1.057 0.0523, 0.1533 0.1700, 0.2266
C20H18NiN6O6 497.11 Monoclinic P2(1)/c 9.651 (6) 17.524 (10) 11.489 (7) 90 97.132 (9) 90 1928.0 (19) 4 1.713 1024 1.063 2.13–27.57 11708 1.000 0.0858, 0.1737 0.1792, 0.2176
C28H30CuN12O6 694.18 Triclinic P1 8.7521 (11) 8.8859 (12) 11.447 (2) 97.866 (2) 109.094 (2) 109.271 (10) 763.6 (2) 1 1.509 359 0.779 2.53–27.49 4805 1.043 0.0409, 0.1088 0.0460, 0.1131
R1 ¼
P
ðj F o j j F c jÞ=
P
j F o j;
P P wR2 ¼ ½ wðF 2o F 2c Þ2 = wðF 2o Þ2 1=2 .
Table 2 Selected bond distances (Å) and angles (°) for compounds 1–4 Compound 1 Cu(1)AO(2)#1 Cu(1)AN(1) Cu(1)AO(3) Cu(1)AN(6)#2 Cu(1)AO(1)#3 O(1)ACu(1)#3 O(2)ACu(1)#4 N(6)ACu(1)#5
1.936(2) 2.028(3) 2.034(2) 2.041(3) 2.284(2) 2.284(2) 1.936(2) 2.041(3)
O(2)#1ACu(1)AN(1) O(2)#1ACu(1)AO(3) N(1)ACu(1)AO(3) O(2)#1ACu(1)AN(6)#2 N(1)ACu(1)AN(6)#2 O(3)ACu(1)AN(6)#2 O(2)#1ACu(1)AO(1)#3 N(1)ACu(1)AO(1)#3 O(3)ACu(1)AO(1)#3
92.09(10) 150.26(11) 87.71(10) 93.38(10) 170.79(11) 91.20(10) 120.47(10) 86.10(10) 89.20(9)
N(6)#2ACu(1)AO(1)#3 C(19)AO(3)ACu(1) C(5)AN(1)ACu(1) C(1)AN(1)ACu(1) C(20)AO(1)ACu(1)#3 C(20)AO(2)ACu(1)#4 C(11)AN(6)ACu(1)#5 C(12)AN(6)ACu(1)#5
84.74(11) 101.82(19) 117.0(2) 125.0(2) 165.9(2) 125.9(2) 116.6(2) 124.1(2)
Compound 2 Co(1)AO(4) Co(1)AO(4)#1 Co(1)AN(1)#1 Co(1)AN(1) Co(1)AO(6)#1 Co(1)AO(6) Co(2)AO(2)#2 Co(2)AO(2) Co(2)AO(5) Co(2)AO(5)#2 Co(2)AN(6)#2 Co(2)AN(6)
2.097(3) 2.097(3) 2.125(3) 2.125(3) 2.128(3) 2.128(3) 2.067(3) 2.067(3) 2.127(3) 2.127(3) 2.163(4) 2.163(4)
O(4)ACo(1)AO(4)#1 O(4)ACo(1)AN(1)#1 O(4)#1ACo(1)AN(1)#1 O(4)ACo(1)AN(1) O(4)#1ACo(1)AN(1) N(1)#1ACo(1)AN(1) O(4)ACo(1)AO(6)#1 O(4)#1ACo(1)AO(6)#1 N(1)#1ACo(1)AO(6)#1 N(1)ACo(1)AO(6)#1 O(4)ACo(1)AO(6) O(4)#1ACo(1)AO(6) N(1)#1ACo(1)AO(6) N(1)ACo(1)AO(6) O(6)#1ACo(1)AO(6) O(2)#2ACo(2)AO(2) O(2)#2ACo(2)AO(5)
180.000(1) 90.04(14) 89.96(14) 89.96(14) 90.04(14) 180.00(13) 90.61(13) 89.39(13) 93.56(13) 86.44(13) 89.39(13) 90.61(13) 86.44(13) 93.56(13) 180.00(17) 180.00(16) 89.90(13)
O(2)ACo(2)AO(5) O(2)#2ACo(2)AO(5)#2 O(2)ACo(2)AO(5)#2 O(5)ACo(2)AO(5)#2 O(2)#2ACo(2)AN(6)#2 O(2)ACo(2)AN(6)#2 O(5)ACo(2)AN(6)#2 O(5)#2ACo(2)AN(6)#2 O(2)#2ACo(2)AN(6) N(6)#2ACo(2)AN(6) C(19)AO(2)ACo(2) C(20)AO(4)ACo(1) C(5)AN(1)ACo(1) C(1)AN(1)ACo(1) C(12)AN(6)ACo(2) C(11)AN(6)ACo(2)
90.10(13) 90.10(13) 89.90(13) 180.0 90.21(13) 89.79(13) 89.04(12) 90.96(12) 89.04(12) 180.0(2) 133.6(3) 129.8(3) 119.4(3) 121.8(3) 120.1(2) 122.3(3)
Compound 3 Ni(1)AO(2)#1 Ni(1)AO(5) Ni(1)AO(4) Ni(1)AO(6) Ni(1)AN(6) Ni(1)AN(1)#2 N(1)ANi(1)#1 O(2)ANi(1)#2
2.001(4) 2.014(4) 2.017(4) 2.125(5) 2.156(6) 2.201(6) 2.201(6) 2.001(4)
O(2)#1ANi(1)AO(5) O(2)#1ANi(1)AO(4) O(5)ANi(1)AO(4) O(2)#1ANi(1)AO(6) O(5)ANi(1)AO(6) O(4)ANi(1)AO(6) O(2)#1ANi(1)AN(6) O(5)ANi(1)AN(6) O(4)ANi(1)AN(6) O(6)ANi(1)AN(6) O(2)#1ANi(1)AN(1)#2
91.09(19) 177.03(19) 85.94(19) 94.51(19) 173.45(19) 88.46(19) 85.85(19) 88.20(19) 94.2(2) 88.82(19) 87.01(19)
O(5)ANi(1)AN(1)#2 O(4)ANi(1)AN(1)#2 O(6)ANi(1)AN(1)#2 N(6)ANi(1)AN(1)#2 C(18)AN(1)ANi(1)#1 C(17)AN(1)ANi(1)#1 C(9)AN(6)ANi(1) C(13)AN(6)ANi(1) C(1)AO(2)ANi(1)#2 C(8)AO(4)ANi(1)
91.86(19) 92.94(19) 91.83(19) 172.9(2) 117.2(4) 125.2(5) 117.6(4) 123.7(4) 131.4(4) 127.4(4)
Compound 4 Cu(1)AO(2)#1 Cu(1)AO(2) Cu(1)AN(6) Cu(1)AN(6)#1 Cu(1)AO(3)
1.9695(16) 1.9695(16) 2.0036(18) 2.0036(18) 2.559(2)
O(2)#1ACu(1)AO(2) O(2)#1ACu(1)AN(6) O(2)ACu(1)AN(6) O(2)#1ACu(1)AN(6)#1 O(2)ACu(1)AN(6)#1 N(6)ACu(1)AN(6)#1 O(2)#1ACu(1)AO(3)
180.0 89.11(7) 90.89(7) 90.89(7) 89.11(7) 180.00(13) 92.56(7)
O(2)ACu(1)AO(3) N(6)ACu(1)AO(3) N(6)#1ACu(1)AO(3) C(2)AO(2)ACu(1) C(14)AN(6)ACu(1) C(13)AN(6)ACu(1)
87.44(7) 90.42(7) 89.58(7) 128.50(16) 118.87(14) 122.24(15)
Symmetry transformations used to generate equivalent atoms: #1 x, y 1, z, #2 x, y 1, z + 1, #3 x + 1, y + 2, z + 1, #4 x, y + 1, z, #5 x, y + 1, z 1 for 1; #1 x + 2, y + 1, z + 1, #2 x + 2, y + 1, z for 2; #1 x + 1, y + 1/2, z + 1/2, #2 x 1, y + 1/2, z 1/2 for 3; #1 x, y, z for 4.
J.-J. Liu et al. / Journal of Molecular Structure 891 (2008) 50–57
2.3. X-ray crystallography Single-crystal XRD data for compounds 1–4 were collected on a Bruker Smart Apex-II CCD diffractometer with graphite monochromatic Mo-Ka radiation (k = 0.71073 Å) at room temperature. Empirical absorption corrections were applied using SADABS program. The structures were solved by direct method with SHELXS-97 program and refined by full-matrix least squares on F2 with SHELXL-97 program [17]. All hydrogen atoms were placed geometrically and all none-hydrogen atoms were refined anisotropically. The crystal data and structural refinement results are given in Table 1. The selected bond distances and angles are presented in Table 2. 3. Results and discussion 3.1. Synthesis and characterization Compounds 1–2 were obtained as polymeric compounds by hydrothermal synthesis, while compounds 3–4 were prepared in
53
mixed solvent systems by slow evaporation at room temperature. We also tried to prepare compound 3 by hydrothermal synthesis, but it was failed. During the reaction process, we found the metal-to-ligand ratio is a key factor for the preparation of these crystalline materials. However, the metal-to-ligand ratio is unrelated for the synthesis of compound 4. The compounds 1–4 contain 3-abpt, carboxylate and coordinated or lattice water, which are in agreement with their IR spectra. The broad absorption bands from 3500 to 3200 cm1 are assigned to coordinated or lattice water with strong hydrogenbonding interactions. The amino group of 3-abpt displays a sharp peak at 3351, 3352, 3374 and 3336 cm1 for 1, 2, 3 and 4, respectively. In the IR spectrum of 1 (or 2), the ip ligand exhibits two mas(COO) strong absorptions at 1627 (1599), 1550 (1546) and two ms(COO) strong absorptions at 1396 (1422), 1371 (1373) cm1. The compound 3(or 4) shows mas(COO) absorption at 1558 (1560) and ms(COO) absorption at 1383 (1410) cm1. The absence of characteristic absorption of mas(COOH) near 1680 cm1 indicates the carboxylic acid are deprotoned for com-
Fig. 1. (a) View of the metal coordination environment in 1 (H atoms and lattice water are omitted for clarity); (b) the ip-bridged ring-like chain structure; (c) the 3-abptbridged ring-like chain structure; (d) the 2D double-layered framework; and (e) schematic illustrating the (4,4) network topology of 1.
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pounds 1–4. Their formulas have been confirmed by elemental analysis data and X-ray structural analysis. 3.2. Description of crystal structures 3.2.1. [Cu(3-abpt)(ip)]n2nH2O (1) X-ray analysis has revealed that the compound 1 displays an interesting 2D layered framework. As shown in Fig. 1(a), each copper atom exhibits distorted octahedral coordination environment, coordinated by four oxygen atoms from three independent carboxylate groups which are in the equatorial positions and two nitrogen
atoms from two 3-abpt ligands which located at the axial positions. The CuAO distances range between 1.936(2) and 2.284(2) Å. The OACuAO bond angles range from 89.20(9) to 150.26(11)°, and the OACuAN bond angles range from 84.74(11) to 93.38(10)°. The ip ligand in compound 1 acts as a tetradentate ligand to link up three copper (II) centers (see Scheme 2E). As shown in Fig. 1(b), one carboxylate group of ip coordinates in a bidentate chelating mode, and the other carboxylate group acts as a bidentate bridge which links copper dimmer with Cu. . .Cu separation of 7.7679(10) Å. This yields a ring-like infinite chain along b axis. From Fig. 1(c), we can see each copper center is also bridged by
Fig. 2. (a) View of the metal coordination environment in 2 (H atoms and lattice water are omitted for clarity) and (b) view of the 1D ring-like chain.
Fig. 3. (a) View of the metal coordination environment in 3 (H atoms are omitted for clarity) and (b) view of the 1D ring-like chain.
J.-J. Liu et al. / Journal of Molecular Structure 891 (2008) 50–57
the 3-abpt linkers which are in trans-arrangement (see Scheme 1A) to form a 1D double-chain. The dihedral angle between the C(1)C(2)C(3)C(4)C(5)N(1) and C(8)C(9)C(10)C(11)C(12)N(6) planes in 3-abpt ligand is 12.18(2)°. The linkages of these two kinds of ring-like chain further generate an unusual 2D double-layered motif (see Fig. 1(d)). From the viewpoint of network topology, we take the adjacent dinuclear Cu(II) as one node, then compound 1 can be simplified as a (4,4) network as shown in Fig. 1(e). 3.2.2. [Co(3-abpt)(ip)(H2O)2]n 2nH2O (2) Compound 2 features a 1D ring-like infinite chain coordination structure in which Co(II) centers are interlinked by ip and 3-abpt bridges. As shown in Fig. 2(a), each Co(II) atom is surrounded by two oxygen donors from two ip, two pyridyl nitrogen atoms from a pair of 3-abpt in cis-arrangement (see Scheme 1B), and two H2O ligands. The CoAO distances range between 2.067(3) and 2.128(3) Å. The CoAN1 and CoAN6 distances are 2.125(3) and 2.163(4) Å, respectively. The OACoAO bond angles range from 89.39(13) to 180.00(1)°, and the OACoAN bond angles range from 86.44(13) to 93.56(13)°. The ip ligand acts as a bidentate bridge links two Co(II) centers in trans-fashion (see Scheme 2H). As shown in Fig. 2(b), the Co(II) centers are bridged by ip and 3-abpt ligands to yield a 1D ring-like chain with Co. . .Co separation of 9.8345(75) Å. The dihedral angle between the C(1)C(2)C(3)C(4)C(5)N(1) and C(8)C(9)C(10)C(11)C(12)N(6) planes in 3-abpt ligand is 29.74(1)°. 3.2.3. [Ni(3-abpt)(tp)(H2O)2]n (3) Compound 3 is a 1D ring-like infinite chain coordination polymer in which Ni(II) centers are interlinked by tp and 3-abpt ligands. As shown in Fig. 3(a), each Ni(II) atom is surrounded by two oxygen donors from two tp, two pyridyl nitrogen atoms from a pair of 3-abpt in cis-arrangement (see Scheme 1B) and two H2O ligands. Similar as the coordination modes of ip in 2, the tp ligand also acts as a bidentate ligand using both monodentate carboxylate groups to link two Ni(II) centers in trans-fashion (see Scheme 2P).
55
The NiAO distances range between 2.001(4) and 2.125(5) Å. NiAN1 and NiAN6 distances are 2.201(6) and 2.156(6) Å, respectively. The OANiAO bond angles range from 85.94(19) to 177.03(19)°, and the OANiAN bond angles range from 85.85(19) to 94.2(2)°. The metal centers are extended by the tp linkers and 3-abpt ligands with Ni(II) centers separation of 10.6520(55) Å to form a 1D ring-like chain (see Fig. 3(b)). The dihedral angle between the C(9)C(10)C(11)C(12)C(13)N(6) and C(16)C(17)C(18) C(19)C(20)N(1) planes in 3-abpt ligand is 51.61(2)°. 3.2.4. [Cu(3-abpt)2(CH3COO)2(H2O)2] (4) Compound 4 is a mononuclear complex which is central symmetric. As shown in Fig. 4(a), the Cu(II) center is in a octahedral environment and coordinated by two acetate oxygen atoms, two pyridyl nitrogen atoms and two H2O ligands. Both 3-abpt act as monodentate ligands bind to the axial sites of the copper center with the CuAN distance of 2.0036(18) Å. The CuAO2 and CuAO3 distances are 1.9695(16) and 2.559(2) Å, respectively. The OACuAO bond angles range from 87.44(7) to 180.0° and the OACuAN bond angles range from 89.11(7) to 90.89(7)°. The dihedral angle between the C(3)C(4)C(5)C(6)C(7)N(1) and C(10)C(11)C(12)C(13)C (14)N(6) planes in 3-abpt ligand is 60.99(1)°. All of these molecules are linked together through weak hydrogen bonding interaction between O3AH3E. . .O1 (x, y, z) and O3AH3F. . .N(2) (x, y, z 1) to form a 3D supramolecular architecture. Comparing the structures of compounds 1–4, 3-abpt ligands in compound 1 surround the Cu(II) centers in a trans-arrangement (see Scheme 1A). However, 3-abpt ligands adopt cis-arrangement in compounds 2 and 3 (see Scheme 1B). In compound 4, 3-abpt is monodentate ligand. Both compounds 2 and 3 have similar 1D ring-like chain structures, but show different dihedral angles between pyridyl planes of 3-abpt. They are 29.74(1) and 51.61(2)° for compounds 2 and 3, respectively. The reasons for these results may be depend on the length of the bridging ligands (ip and tp) and different metal centers.
Fig. 4. (a) View of the metal coordination environment in 4 (H atoms are omitted for clarity) and (b) view of the structure of 4 in a unit cell.
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product [CuO(3-abpt)] which is further decomposed in 465– 750 °C. The final residue at 800 °C is CuO (found 17.75%, calcd 15.85%). Compound 2 loses lattice and coordinated water in the range 90–183 °C (endothermic peak at 156 °C) with a weight-loss of 13.53% (calcd 13.51%). The ip ligand is released in 290–460 °C with a weight-loss of 30.27% (calcd 27.77%), resulting in an intermediate product [CoO(3-abpt)] formed. This intermediate product is further decomposed in 480–750 °C with a final residue Co2O3 formed (found 15.59%, calcd 15.55%). Compound 3 loses coordinated water (found 8.42%, calcd 7.25%) in higher temperature from 180 to 255 °C with an endothermic peak at 236 °C. The tp ligand is released in 300–400 °C with a weight-loss of 33.35% (calcd 29.80%). The intermediate product [NiO(3-abpt)] is further decomposed in 430–750 °C with a final residue NiO formed (found 12.25%, calcd 15.03%). 4. Conclusions This study demonstrates that 4-amino-3,5-bis(3-pyridyl)-1,2,4triazole (3-abpt) is capable of coordinating metal centers with Npyridyl donors, and generates novel coordination polymers. However, the relative orientation of Npyridyl donor connector 3-abpt and angular (ip) or linear (tp) building blocks results in the final structural arrays. This result undoubtedly discovers the tectonic effect of ligands in metal-organic frameworks. As expected, the metal centers also play a structure-directing role on the construction of coordination networks. This work prompts us to achieve more functional crystalline materials by employing a bent ligand 3-abpt and other angular or linear ligands, and further efforts on this perspective are underway. 5. Supplementary data Crystallographic data of compounds 1–4 have been deposited at the Cambridge Crystallographic Data Center with CCDC 672030– 672033, which can be obtained free of charge at www.ccdc.cam.ac.uk/conts/retrieving.html (or from the Cambridge Crystallographic Data Centre, 12, Union Road, Cambridge CB2 1EZ, UK). Email: [email protected]]. Acknowledgments Financially supported by the Research Foundation for Returned Chinese Scholars Overseas of Chinese Education Ministry (7A14219), the Development Foundation of Shanghai Education Commission (03AK35), the Science Foundation for the Excellent Youth Scholars of Higher Education of Shanghai, and the Innovation Foundation of Shanghai University. References
Fig. 5. The thermal analysis (TG-DSC) curves of compounds 1–3.
3.3. Thermal stabilities of compounds 1–3 The thermal stabilities of three coordination polymers 1–3 have been investigated by thermogravimetric analysis as shown in Fig. 5. Compound 1 displays a weight-loss of 6.47% in the range 76–131 °C with an endothermic peak at 106 °C, corresponding to expulsion of two lattice water molecules (calcd 7.18%). The main framework remains intact until it is heated to 280 °C, and then releases ip ligand fast with an exothermic peak at 286 °C (found 29.80%, calcd 29.51%). This process may afford an intermediate
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Journal of Molecular Structure journal homepage: www.elsevier.com/locate/molstruc
Syntheses, structures and thermal stabilities of four complexes with 4-amino-3,5-bis(3-pyridyl)-1,2,4-triazole ligand Jing-Jing Liu a, Xiang He a,*, Min Shao b, Ming-Xing Li a,* a b
Department of Chemistry, College of Science, Shanghai University, Shanghai 200444, China Instrumental Analysis and Research Center, Shanghai University, Shanghai 200444, China
a r t i c l e
i n f o
Article history: Received 9 January 2008 Accepted 4 March 2008 Available online 20 March 2008 Keywords: 4-Amino-3,5-bis(3-pyridyl)-1,2,4-triazole Transition metal complex Crystal structure Coordination polymers Thermal analysis
a b s t r a c t Reactions of 4-amino-3,5-bis(3-pyridyl)-1,2,4-triazole (3-abpt) with metal acetates gave rise to four new complexes [Cu(3-abpt)(ip)]n2nH2O (1), [Co(3-abpt)(ip)(H2O)2]n2nH2O (2), [Ni(3-abpt)(tp)(H2O)2]n(3) and [Cu(3-abpt)2(CH3COO)2(H2O)2] (4) (ip = isophthalate, tp = terephthalate), which were characterized by EA, IR and X-ray crystallography. Compound 1 consists of two kinds of ring-like chain which are interconnected to form an unusual two-dimensional layered motif. Compounds 2 and 3 are both 1D ring-like infinite chains. Compound 4 is a mononuclear complex. The thermal stabilities of coordination polymers 1–3 have been investigated. Ó 2008 Elsevier B.V. All rights reserved.
1. Introduction
2. Experimental
Coordination polymers with well-designed shape and functionality have attracted considerable attention recently [1]. Suitable ligands with appropriate coordination sites linked by specific connectors have been proved to be an efficient route for the formation of coordination polymers with desirable structure topologies and potential applications in catalysis, biology and material science [2–6]. Currently, triazole ligands as well as their derivatives, known for their rich coordination modes and wide applications as multidentate bridging ligands in coordination chemistry, are of considerable interesting in constructing coordination polymers [7]. 4Amino-3,5-bis(3-pyridyl)-1,2,4-triazole (3-abpt) can provide three typical conformations (see Scheme 1) under appropriate surroundings, and it can be served as a good candidate for the construction of the molecular cages [8], rings [9], grids [10] and ladders [11]. On the other hand, it is well known that carboxylate ligands, especially isophthalate (ip) and terephthalate (tp), present a high structural effect in assembling coordination polymers due to their numerous possible coordination modes (see Scheme 2) [12–15]. We select CuII, CoII and NiII as metal nodes to obtain four complexes, namely [Cu(3abpt)(ip)]n2nH2O (1), [Co(3-abpt)(ip)(H2O)2]n2nH2O (2), [Ni(3abpt)(tp)(H2O)2]n (3) and [Cu(3-abpt)2(CH3COO)2(H2O)2] (4). Herein, we report their syntheses, structures and thermal stabilities.
2.1. Materials and methods
* Corresponding authors. E-mail addresses: [email protected] (X. He), [email protected] (M.-X. Li). 0022-2860/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.molstruc.2008.03.011
The ligand 4-amino-3,5-bis(3-pyridyl)-1,2,4-triazole was prepared according to the literature method [16]. Other chemicals were of reagent grade and used as purchased without further purification. Elemental analyses (EA) were performed on a Vario EL III analyzer. Infrared spectra (IR) were recorded with a Nicolet A370 FT-IR spectrometer by KBr pellets in the range 400–4000 cm1. Thermogravimetric analyses (TG-DSC) were completed on a Netzsch STA 449C thermal analyzer at a heating rate of 10 °C/min in air. 2.2. Synthesis [Cu(3-abpt)(ip)]n2nH2O (1): a mixture of Cu(OAc)2H2O (0.048 g, 0.24 mmol), 3-abpt (0.048 g, 0.20 mmol), H2ip (0.033 g, 0.20 mmol) and water (16 mL) was sealed in a Teflon-lined stainless steel vessel (25 mL), which was heated at 140 °C for 3 days and then cooled to room temperature at a rate of 10 °C/h. Green rhombus crystals of 1 were collected in 48% yield (0.048 g, based on 3-abpt). Anal. Calcd for C20H18CuN6O6: C, 47.86; H, 3.61; N, 16.74%. Found: C, 48.03; H, 3.61; N, 16.58%. IR (KBr pellet, cm1): 3425m, 3351m, 3174w, 3097w, 1627vs, 1550s, 1441m, 1396s, 1371vs, 823m, 739m, 720s, 694m, 652w. [Co(3-abpt)(ip)(H2O)2]n2nH2O (2): a mixture of Co(OAc)24H2O (0.030 g, 0.12 mmol), 3-abpt (0.024 g, 0.10 mmol), H2ip (0.017 g, 0.10 mmol) and water (10 mL) was sealed in a Teflon-lined stainless steel vessel (15 mL), which was heated at 140 °C for 3
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J.-J. Liu et al. / Journal of Molecular Structure 891 (2008) 50–57 N
N
N
N
M N
N
N
N
NH 2
NH 2
N
N
N
M
M
M
A
N
M
M N
N
N NH 2
B
C
Scheme 1. Three typical conformations presented by 3-abpt.
O
O
O
O
C
C
C
C
O
O
O
O
O
M
A
O
O
B
O
O
M
O C
C
O
O
O
O C
C
M
O
O
M
O
D
O
C
M
M
C
O
O
C
C
O
O
O O
M
M
E
M
M
M
F
M
G
H
O
O C
C
O
O
M
M
O
O C
M
M
C O
O
M
O
O
O
O
O C
O C
O
O
N
O
C MM
M M
O C
C O
O
O
M O
M
O
M
C
O
O
L
C
M
M
C
O
M
O
O
O
O C
M
K
O
M
C
O C
G
O C
O
C
I
M
C
M M
O
C
C
C
C
O
O
O
M
M
O
P
O
M
O
M
C
Q
Scheme 2. Possible coordination modes presented by the carboxylate groups of ip and tp.
days and then cooled to room temperature at a rate of 10 °C/h. A clear pink solution was obtained, and the filtrate was left to stand for 3 days at room temperature. Pink prism crystals of 2 were collected in 52% yield (0.028 g, based on 3-abpt). Anal. Calcd for C20H22CoN6O8: C, 45.04; H, 4.16; N, 15.76%. Found: C, 45.29; H, 4.14; N, 15.70%. IR (KBr pellet, cm1): 3352s, 3143s, 1670w, 1599s, 1546vs, 1480m, 1422s, 1373vs, 819w, 761m, 705s. [Ni(3-abpt)(tp)(H2O)2]n (3): an aqueous (10 mL) solution of Ni(OAc)24H2O (0.027 g, 0.11 mmol) was slowly added to a solution of 3-abpt (0.024 g, 0.10 mmol) in ethanol (10 mL) with stirring for 30 min. Then a solution of H2tp (0.017 g, 0.10 mmol) in DMF (5 mL) was added to above mixture with continuous stirring for another 30 min and filtrated. The filtrate was left to stand for 2 weeks at room temperature. Green block crystals of 3 were col-
lected in 36% yield (0.018 g, based on 3-abpt). Anal. Calcd for C20H18NiN6O6: C, 48.32; H, 3.65; N, 16.91%. Found: C, 48.07; H, 3.85; N, 16.64%. IR (KBr pellet, cm1): 3374m, 3200w, 3079w, 1558vs, 1383vs, 1033m, 1018m, 799s, 753s, 699s, 519m. [Cu(3-abpt)2(CH3COO)2(H2O)2] (4): an aqueous (10 mL) solution of Cu(OAc)2H2O (0.040 g, 0.20 mmol) was slowly added to a solution of 3-abpt (0.048 g, 0.2 mmol) in methanol (10 mL). The mixture was stirred for about 20 min and left to stand for 2 weeks at room temperature. Blue block crystals of 4 were obtained in 30% yield (0.042 g, based on 3-abpt). Anal. Calcd for C28H30CuN12O6: C, 48.45; H, 4.36; N, 24.21%. Found: C, 48.35; H, 4.36; N, 23.84%. IR (KBr pellet, cm1): 3336m, 3238m, 3115w, 3015w, 1560vs, 1480w, 1451w, 1410vs, 1340m, 1197w, 1031w, 981m, 821m, 703s, 662w, 624w.
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J.-J. Liu et al. / Journal of Molecular Structure 891 (2008) 50–57
Table 1 Crystal data and structural refinement for compounds 1–4 Compound
1
2
3
4
Formula Formula weight Crystal system Space group a (Å) b (Å) c (Å) a (°) b (°) c (°) V (Å3) Z Dc (g cm3) F(0 0 0) l (mm1) h for data collection (°) Reflections collected Goodness-of-fit on F2 R1, wR2 [I > 2r(I)] R1, wR2 (all data)
C20H18CuN6O6 501.95 Triclinic P1 9.0805 (11) 10.0891 (11) 12.4016 (15) 66.849 (10) 89.442 (10) 79.389 (10) 1024.3 (2) 2 1.621 510 1.119 2.24–27.49 6448 1.097 0.0475, 0.1424 0.0598, 0.1589
C20H22CoN6O8 533.36 Monoclinic P2(1)/c 8.462 (7) 14.457 (12) 19.669 (15) 90 110.76 (3) 90 2250 (3) 4 1.563 1084 0.823 2.57–27.57 11531 1.057 0.0523, 0.1533 0.1700, 0.2266
C20H18NiN6O6 497.11 Monoclinic P2(1)/c 9.651 (6) 17.524 (10) 11.489 (7) 90 97.132 (9) 90 1928.0 (19) 4 1.713 1024 1.063 2.13–27.57 11708 1.000 0.0858, 0.1737 0.1792, 0.2176
C28H30CuN12O6 694.18 Triclinic P1 8.7521 (11) 8.8859 (12) 11.447 (2) 97.866 (2) 109.094 (2) 109.271 (10) 763.6 (2) 1 1.509 359 0.779 2.53–27.49 4805 1.043 0.0409, 0.1088 0.0460, 0.1131
R1 ¼
P
ðj F o j j F c jÞ=
P
j F o j;
P P wR2 ¼ ½ wðF 2o F 2c Þ2 = wðF 2o Þ2 1=2 .
Table 2 Selected bond distances (Å) and angles (°) for compounds 1–4 Compound 1 Cu(1)AO(2)#1 Cu(1)AN(1) Cu(1)AO(3) Cu(1)AN(6)#2 Cu(1)AO(1)#3 O(1)ACu(1)#3 O(2)ACu(1)#4 N(6)ACu(1)#5
1.936(2) 2.028(3) 2.034(2) 2.041(3) 2.284(2) 2.284(2) 1.936(2) 2.041(3)
O(2)#1ACu(1)AN(1) O(2)#1ACu(1)AO(3) N(1)ACu(1)AO(3) O(2)#1ACu(1)AN(6)#2 N(1)ACu(1)AN(6)#2 O(3)ACu(1)AN(6)#2 O(2)#1ACu(1)AO(1)#3 N(1)ACu(1)AO(1)#3 O(3)ACu(1)AO(1)#3
92.09(10) 150.26(11) 87.71(10) 93.38(10) 170.79(11) 91.20(10) 120.47(10) 86.10(10) 89.20(9)
N(6)#2ACu(1)AO(1)#3 C(19)AO(3)ACu(1) C(5)AN(1)ACu(1) C(1)AN(1)ACu(1) C(20)AO(1)ACu(1)#3 C(20)AO(2)ACu(1)#4 C(11)AN(6)ACu(1)#5 C(12)AN(6)ACu(1)#5
84.74(11) 101.82(19) 117.0(2) 125.0(2) 165.9(2) 125.9(2) 116.6(2) 124.1(2)
Compound 2 Co(1)AO(4) Co(1)AO(4)#1 Co(1)AN(1)#1 Co(1)AN(1) Co(1)AO(6)#1 Co(1)AO(6) Co(2)AO(2)#2 Co(2)AO(2) Co(2)AO(5) Co(2)AO(5)#2 Co(2)AN(6)#2 Co(2)AN(6)
2.097(3) 2.097(3) 2.125(3) 2.125(3) 2.128(3) 2.128(3) 2.067(3) 2.067(3) 2.127(3) 2.127(3) 2.163(4) 2.163(4)
O(4)ACo(1)AO(4)#1 O(4)ACo(1)AN(1)#1 O(4)#1ACo(1)AN(1)#1 O(4)ACo(1)AN(1) O(4)#1ACo(1)AN(1) N(1)#1ACo(1)AN(1) O(4)ACo(1)AO(6)#1 O(4)#1ACo(1)AO(6)#1 N(1)#1ACo(1)AO(6)#1 N(1)ACo(1)AO(6)#1 O(4)ACo(1)AO(6) O(4)#1ACo(1)AO(6) N(1)#1ACo(1)AO(6) N(1)ACo(1)AO(6) O(6)#1ACo(1)AO(6) O(2)#2ACo(2)AO(2) O(2)#2ACo(2)AO(5)
180.000(1) 90.04(14) 89.96(14) 89.96(14) 90.04(14) 180.00(13) 90.61(13) 89.39(13) 93.56(13) 86.44(13) 89.39(13) 90.61(13) 86.44(13) 93.56(13) 180.00(17) 180.00(16) 89.90(13)
O(2)ACo(2)AO(5) O(2)#2ACo(2)AO(5)#2 O(2)ACo(2)AO(5)#2 O(5)ACo(2)AO(5)#2 O(2)#2ACo(2)AN(6)#2 O(2)ACo(2)AN(6)#2 O(5)ACo(2)AN(6)#2 O(5)#2ACo(2)AN(6)#2 O(2)#2ACo(2)AN(6) N(6)#2ACo(2)AN(6) C(19)AO(2)ACo(2) C(20)AO(4)ACo(1) C(5)AN(1)ACo(1) C(1)AN(1)ACo(1) C(12)AN(6)ACo(2) C(11)AN(6)ACo(2)
90.10(13) 90.10(13) 89.90(13) 180.0 90.21(13) 89.79(13) 89.04(12) 90.96(12) 89.04(12) 180.0(2) 133.6(3) 129.8(3) 119.4(3) 121.8(3) 120.1(2) 122.3(3)
Compound 3 Ni(1)AO(2)#1 Ni(1)AO(5) Ni(1)AO(4) Ni(1)AO(6) Ni(1)AN(6) Ni(1)AN(1)#2 N(1)ANi(1)#1 O(2)ANi(1)#2
2.001(4) 2.014(4) 2.017(4) 2.125(5) 2.156(6) 2.201(6) 2.201(6) 2.001(4)
O(2)#1ANi(1)AO(5) O(2)#1ANi(1)AO(4) O(5)ANi(1)AO(4) O(2)#1ANi(1)AO(6) O(5)ANi(1)AO(6) O(4)ANi(1)AO(6) O(2)#1ANi(1)AN(6) O(5)ANi(1)AN(6) O(4)ANi(1)AN(6) O(6)ANi(1)AN(6) O(2)#1ANi(1)AN(1)#2
91.09(19) 177.03(19) 85.94(19) 94.51(19) 173.45(19) 88.46(19) 85.85(19) 88.20(19) 94.2(2) 88.82(19) 87.01(19)
O(5)ANi(1)AN(1)#2 O(4)ANi(1)AN(1)#2 O(6)ANi(1)AN(1)#2 N(6)ANi(1)AN(1)#2 C(18)AN(1)ANi(1)#1 C(17)AN(1)ANi(1)#1 C(9)AN(6)ANi(1) C(13)AN(6)ANi(1) C(1)AO(2)ANi(1)#2 C(8)AO(4)ANi(1)
91.86(19) 92.94(19) 91.83(19) 172.9(2) 117.2(4) 125.2(5) 117.6(4) 123.7(4) 131.4(4) 127.4(4)
Compound 4 Cu(1)AO(2)#1 Cu(1)AO(2) Cu(1)AN(6) Cu(1)AN(6)#1 Cu(1)AO(3)
1.9695(16) 1.9695(16) 2.0036(18) 2.0036(18) 2.559(2)
O(2)#1ACu(1)AO(2) O(2)#1ACu(1)AN(6) O(2)ACu(1)AN(6) O(2)#1ACu(1)AN(6)#1 O(2)ACu(1)AN(6)#1 N(6)ACu(1)AN(6)#1 O(2)#1ACu(1)AO(3)
180.0 89.11(7) 90.89(7) 90.89(7) 89.11(7) 180.00(13) 92.56(7)
O(2)ACu(1)AO(3) N(6)ACu(1)AO(3) N(6)#1ACu(1)AO(3) C(2)AO(2)ACu(1) C(14)AN(6)ACu(1) C(13)AN(6)ACu(1)
87.44(7) 90.42(7) 89.58(7) 128.50(16) 118.87(14) 122.24(15)
Symmetry transformations used to generate equivalent atoms: #1 x, y 1, z, #2 x, y 1, z + 1, #3 x + 1, y + 2, z + 1, #4 x, y + 1, z, #5 x, y + 1, z 1 for 1; #1 x + 2, y + 1, z + 1, #2 x + 2, y + 1, z for 2; #1 x + 1, y + 1/2, z + 1/2, #2 x 1, y + 1/2, z 1/2 for 3; #1 x, y, z for 4.
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2.3. X-ray crystallography Single-crystal XRD data for compounds 1–4 were collected on a Bruker Smart Apex-II CCD diffractometer with graphite monochromatic Mo-Ka radiation (k = 0.71073 Å) at room temperature. Empirical absorption corrections were applied using SADABS program. The structures were solved by direct method with SHELXS-97 program and refined by full-matrix least squares on F2 with SHELXL-97 program [17]. All hydrogen atoms were placed geometrically and all none-hydrogen atoms were refined anisotropically. The crystal data and structural refinement results are given in Table 1. The selected bond distances and angles are presented in Table 2. 3. Results and discussion 3.1. Synthesis and characterization Compounds 1–2 were obtained as polymeric compounds by hydrothermal synthesis, while compounds 3–4 were prepared in
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mixed solvent systems by slow evaporation at room temperature. We also tried to prepare compound 3 by hydrothermal synthesis, but it was failed. During the reaction process, we found the metal-to-ligand ratio is a key factor for the preparation of these crystalline materials. However, the metal-to-ligand ratio is unrelated for the synthesis of compound 4. The compounds 1–4 contain 3-abpt, carboxylate and coordinated or lattice water, which are in agreement with their IR spectra. The broad absorption bands from 3500 to 3200 cm1 are assigned to coordinated or lattice water with strong hydrogenbonding interactions. The amino group of 3-abpt displays a sharp peak at 3351, 3352, 3374 and 3336 cm1 for 1, 2, 3 and 4, respectively. In the IR spectrum of 1 (or 2), the ip ligand exhibits two mas(COO) strong absorptions at 1627 (1599), 1550 (1546) and two ms(COO) strong absorptions at 1396 (1422), 1371 (1373) cm1. The compound 3(or 4) shows mas(COO) absorption at 1558 (1560) and ms(COO) absorption at 1383 (1410) cm1. The absence of characteristic absorption of mas(COOH) near 1680 cm1 indicates the carboxylic acid are deprotoned for com-
Fig. 1. (a) View of the metal coordination environment in 1 (H atoms and lattice water are omitted for clarity); (b) the ip-bridged ring-like chain structure; (c) the 3-abptbridged ring-like chain structure; (d) the 2D double-layered framework; and (e) schematic illustrating the (4,4) network topology of 1.
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pounds 1–4. Their formulas have been confirmed by elemental analysis data and X-ray structural analysis. 3.2. Description of crystal structures 3.2.1. [Cu(3-abpt)(ip)]n2nH2O (1) X-ray analysis has revealed that the compound 1 displays an interesting 2D layered framework. As shown in Fig. 1(a), each copper atom exhibits distorted octahedral coordination environment, coordinated by four oxygen atoms from three independent carboxylate groups which are in the equatorial positions and two nitrogen
atoms from two 3-abpt ligands which located at the axial positions. The CuAO distances range between 1.936(2) and 2.284(2) Å. The OACuAO bond angles range from 89.20(9) to 150.26(11)°, and the OACuAN bond angles range from 84.74(11) to 93.38(10)°. The ip ligand in compound 1 acts as a tetradentate ligand to link up three copper (II) centers (see Scheme 2E). As shown in Fig. 1(b), one carboxylate group of ip coordinates in a bidentate chelating mode, and the other carboxylate group acts as a bidentate bridge which links copper dimmer with Cu. . .Cu separation of 7.7679(10) Å. This yields a ring-like infinite chain along b axis. From Fig. 1(c), we can see each copper center is also bridged by
Fig. 2. (a) View of the metal coordination environment in 2 (H atoms and lattice water are omitted for clarity) and (b) view of the 1D ring-like chain.
Fig. 3. (a) View of the metal coordination environment in 3 (H atoms are omitted for clarity) and (b) view of the 1D ring-like chain.
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the 3-abpt linkers which are in trans-arrangement (see Scheme 1A) to form a 1D double-chain. The dihedral angle between the C(1)C(2)C(3)C(4)C(5)N(1) and C(8)C(9)C(10)C(11)C(12)N(6) planes in 3-abpt ligand is 12.18(2)°. The linkages of these two kinds of ring-like chain further generate an unusual 2D double-layered motif (see Fig. 1(d)). From the viewpoint of network topology, we take the adjacent dinuclear Cu(II) as one node, then compound 1 can be simplified as a (4,4) network as shown in Fig. 1(e). 3.2.2. [Co(3-abpt)(ip)(H2O)2]n 2nH2O (2) Compound 2 features a 1D ring-like infinite chain coordination structure in which Co(II) centers are interlinked by ip and 3-abpt bridges. As shown in Fig. 2(a), each Co(II) atom is surrounded by two oxygen donors from two ip, two pyridyl nitrogen atoms from a pair of 3-abpt in cis-arrangement (see Scheme 1B), and two H2O ligands. The CoAO distances range between 2.067(3) and 2.128(3) Å. The CoAN1 and CoAN6 distances are 2.125(3) and 2.163(4) Å, respectively. The OACoAO bond angles range from 89.39(13) to 180.00(1)°, and the OACoAN bond angles range from 86.44(13) to 93.56(13)°. The ip ligand acts as a bidentate bridge links two Co(II) centers in trans-fashion (see Scheme 2H). As shown in Fig. 2(b), the Co(II) centers are bridged by ip and 3-abpt ligands to yield a 1D ring-like chain with Co. . .Co separation of 9.8345(75) Å. The dihedral angle between the C(1)C(2)C(3)C(4)C(5)N(1) and C(8)C(9)C(10)C(11)C(12)N(6) planes in 3-abpt ligand is 29.74(1)°. 3.2.3. [Ni(3-abpt)(tp)(H2O)2]n (3) Compound 3 is a 1D ring-like infinite chain coordination polymer in which Ni(II) centers are interlinked by tp and 3-abpt ligands. As shown in Fig. 3(a), each Ni(II) atom is surrounded by two oxygen donors from two tp, two pyridyl nitrogen atoms from a pair of 3-abpt in cis-arrangement (see Scheme 1B) and two H2O ligands. Similar as the coordination modes of ip in 2, the tp ligand also acts as a bidentate ligand using both monodentate carboxylate groups to link two Ni(II) centers in trans-fashion (see Scheme 2P).
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The NiAO distances range between 2.001(4) and 2.125(5) Å. NiAN1 and NiAN6 distances are 2.201(6) and 2.156(6) Å, respectively. The OANiAO bond angles range from 85.94(19) to 177.03(19)°, and the OANiAN bond angles range from 85.85(19) to 94.2(2)°. The metal centers are extended by the tp linkers and 3-abpt ligands with Ni(II) centers separation of 10.6520(55) Å to form a 1D ring-like chain (see Fig. 3(b)). The dihedral angle between the C(9)C(10)C(11)C(12)C(13)N(6) and C(16)C(17)C(18) C(19)C(20)N(1) planes in 3-abpt ligand is 51.61(2)°. 3.2.4. [Cu(3-abpt)2(CH3COO)2(H2O)2] (4) Compound 4 is a mononuclear complex which is central symmetric. As shown in Fig. 4(a), the Cu(II) center is in a octahedral environment and coordinated by two acetate oxygen atoms, two pyridyl nitrogen atoms and two H2O ligands. Both 3-abpt act as monodentate ligands bind to the axial sites of the copper center with the CuAN distance of 2.0036(18) Å. The CuAO2 and CuAO3 distances are 1.9695(16) and 2.559(2) Å, respectively. The OACuAO bond angles range from 87.44(7) to 180.0° and the OACuAN bond angles range from 89.11(7) to 90.89(7)°. The dihedral angle between the C(3)C(4)C(5)C(6)C(7)N(1) and C(10)C(11)C(12)C(13)C (14)N(6) planes in 3-abpt ligand is 60.99(1)°. All of these molecules are linked together through weak hydrogen bonding interaction between O3AH3E. . .O1 (x, y, z) and O3AH3F. . .N(2) (x, y, z 1) to form a 3D supramolecular architecture. Comparing the structures of compounds 1–4, 3-abpt ligands in compound 1 surround the Cu(II) centers in a trans-arrangement (see Scheme 1A). However, 3-abpt ligands adopt cis-arrangement in compounds 2 and 3 (see Scheme 1B). In compound 4, 3-abpt is monodentate ligand. Both compounds 2 and 3 have similar 1D ring-like chain structures, but show different dihedral angles between pyridyl planes of 3-abpt. They are 29.74(1) and 51.61(2)° for compounds 2 and 3, respectively. The reasons for these results may be depend on the length of the bridging ligands (ip and tp) and different metal centers.
Fig. 4. (a) View of the metal coordination environment in 4 (H atoms are omitted for clarity) and (b) view of the structure of 4 in a unit cell.
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product [CuO(3-abpt)] which is further decomposed in 465– 750 °C. The final residue at 800 °C is CuO (found 17.75%, calcd 15.85%). Compound 2 loses lattice and coordinated water in the range 90–183 °C (endothermic peak at 156 °C) with a weight-loss of 13.53% (calcd 13.51%). The ip ligand is released in 290–460 °C with a weight-loss of 30.27% (calcd 27.77%), resulting in an intermediate product [CoO(3-abpt)] formed. This intermediate product is further decomposed in 480–750 °C with a final residue Co2O3 formed (found 15.59%, calcd 15.55%). Compound 3 loses coordinated water (found 8.42%, calcd 7.25%) in higher temperature from 180 to 255 °C with an endothermic peak at 236 °C. The tp ligand is released in 300–400 °C with a weight-loss of 33.35% (calcd 29.80%). The intermediate product [NiO(3-abpt)] is further decomposed in 430–750 °C with a final residue NiO formed (found 12.25%, calcd 15.03%). 4. Conclusions This study demonstrates that 4-amino-3,5-bis(3-pyridyl)-1,2,4triazole (3-abpt) is capable of coordinating metal centers with Npyridyl donors, and generates novel coordination polymers. However, the relative orientation of Npyridyl donor connector 3-abpt and angular (ip) or linear (tp) building blocks results in the final structural arrays. This result undoubtedly discovers the tectonic effect of ligands in metal-organic frameworks. As expected, the metal centers also play a structure-directing role on the construction of coordination networks. This work prompts us to achieve more functional crystalline materials by employing a bent ligand 3-abpt and other angular or linear ligands, and further efforts on this perspective are underway. 5. Supplementary data Crystallographic data of compounds 1–4 have been deposited at the Cambridge Crystallographic Data Center with CCDC 672030– 672033, which can be obtained free of charge at www.ccdc.cam.ac.uk/conts/retrieving.html (or from the Cambridge Crystallographic Data Centre, 12, Union Road, Cambridge CB2 1EZ, UK). Email: [email protected]]. Acknowledgments Financially supported by the Research Foundation for Returned Chinese Scholars Overseas of Chinese Education Ministry (7A14219), the Development Foundation of Shanghai Education Commission (03AK35), the Science Foundation for the Excellent Youth Scholars of Higher Education of Shanghai, and the Innovation Foundation of Shanghai University. References
Fig. 5. The thermal analysis (TG-DSC) curves of compounds 1–3.
3.3. Thermal stabilities of compounds 1–3 The thermal stabilities of three coordination polymers 1–3 have been investigated by thermogravimetric analysis as shown in Fig. 5. Compound 1 displays a weight-loss of 6.47% in the range 76–131 °C with an endothermic peak at 106 °C, corresponding to expulsion of two lattice water molecules (calcd 7.18%). The main framework remains intact until it is heated to 280 °C, and then releases ip ligand fast with an exothermic peak at 286 °C (found 29.80%, calcd 29.51%). This process may afford an intermediate
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