256
J. Wang et al. / Journal of Molecular Structure 1068 (2014) 255–260
Table 1
with versatile structural motifs. Simultaneously, these flexible
bis(N-heterocycle) ligands with their conformational freedoms
increase the coordination versatility and provide additional
spacing and the formation of stable open frameworks [25–28]. A
number of coordination polymers based on the flexible
bis(N-heterocycle) ligands have been reported [29–32]. For the flex-
ible bis(N-heterocycle) ligands, 1,4-bis(1,2,4-triazol-1-ylmethyl)-
benzene (btx) possesses the merits of triazole which can coordinate
with the metal ions in various modes. In addition, the phenylene
ring and triazole ring can freely rotate to meet the requirements
of the coordination geometries of metal atoms on the basis of its
–CH2– spacer [33–35]. A few coordination polymers based on btx
ligand has been reported, which exhibit the interesting structures
and properties [36–42].
With this background information, we choose the bis(N-hetero-
cycle) flexible ligand 1,4-bis(1,2,4-triazol-1-ylmethyl)benzene(btx)
as bridging ligands in combination with isophthalic acid/oxalate to
build new coordination polymers. Two new polymers, namely,
[Ni(btx)(ip)(H2O)] (1) and [Co(btx)(ox)]ꢁ2H2O (2) (H2ip = isophthalic
acid; ox = oxalate) have been constructed successfully. Both two
compounds exhibit two-dimensional layer structure. We report
herein the synthesis, crystal structure, and magnetic properties of
the two compounds. Magnetic data reveal weak antiferromagnetic
coupling for compounds 1 and 2.
Crystal data and structure refinements for compounds 1 and 2.
Empirical formula
Formula weight
Crystal system
space group
a(Å)
C20H18N6NiO5
481.09
Triclinic
C14H16CoN6O6
423.26
Triclinic
Pı
¯
Pı
¯
10.118(2)
10.399(2)
11.026(2)
73.03(3)
68.12(3)
69.96(3)
993.3(3)
1.615
5.4013(11)
8.9450(18)
9.6153(19)
75.25(3)
79.13 (3)
85.84(3)
441.04(15)
1.594
217
b(Å)
c(Å)
a
(°)
b(°)
c
(°)
V(Å3)
qcalc (mg/m3)
F(000)
500
Crystal size (mm3) 0.18 ꢃ 0.17 ꢃ 0.20
0.16 ꢃ 0.14 ꢃ 0.10
h rang for data
collection (°)
3.20–25.01
2.23–25.01
Limiting indices
ꢂ12 6 h 6 ꢂ12;
ꢂ12 6 k 6 ꢂ12;
ꢂ13 6 l 6 ꢂ13
ꢂ6 6 h 6 ꢂ5;
ꢂ10 6 k 6 ꢂ10;
ꢂ11 6 l 6 ꢂ10
1.070
Goodness-of-fit on 1.056
F2
R1, wR2 [I > 2
Max. difference
r
(I)] 0.0369/0.0959
0.970, ꢂ0.533
0.0572/0.1599
0.667, ꢂ0.715
peak, hole
(eÅꢂ3
)
Experimental
Table 2
Selected bond distances (Å) and angles (°) for compound 1.
Materials and physical measurements
Ni(1)–O(4)#1
Ni(1)–N(4)
Ni(1)–O(1)
2.0021(19)
2.050(2)
2.058(2)
90.27(9)
85.85(9)
177.38(9)
101.40(8)
161.82(8)
162.99(8)
100.39(8)
61.61(7)
128.3(2)
123.09(18)
88.55(14)
Ni(1)–N(1)
Ni(1)–O(2)
Ni(1)–O(3)
2.069(2)
2.113(2)
2.1424(18)
96.54(8)
91.36(9)
91.92(9)
91.09(9)
90.60(9)
89.33(8)
89.72(9)
128.3(2)
132.72(19)
90.25(15)
125.6(2)
All commercially available reagents were used as received with-
out further purification. The ligand 1,4-bis(1,2,4-triazol-1-
ylmethyl)benzene was prepared according to the reported proce-
dures [43]. Elemental analysis (EA) for C, H, and N was performed
on a Perkin–Elmer 240 analyzer. Variable-temperature magnetic
susceptibilities were measured on a SQUID MPMS XL-7 magne-
tometer. Diamagnetic corrections were made with Pascal’s con-
stants for all the constituent atoms.
O(4)#1–Ni(1)–N(4)
N(4)–Ni(1)–O(1)
N(4)–Ni(1)–N(1)
O(4)#1–Ni(1)–O(2)
O(1)–Ni(1)–O(2)
O(4)#1–Ni(1)–O(3)
O(1)–Ni(1)–O(3)
O(2)–Ni(1)–O(3)
C(16)–N(1)–Ni(1)
C(8)–N(4)–Ni(1)
C(1)–O(3)–Ni(1)
O(4)#1–Ni(1)–O(1)
O(4)#1–Ni(1)–N(1)
O(1)–Ni(1)–N(1)
N(4)–Ni(1)–O(2)
N(1)–Ni(1)–O(2)
N(4)–Ni(1)–O(3)
N(1)–Ni(1)–O(3)
C(12)–N(1)–Ni(1)
C(2)–N(4)–Ni(1)
C(1)–O(2)–Ni(1)
C(14)–O(4)–Ni(1)#4
Synthesis of complexes
Symmetry transformations used to generate equivalent atoms: #1: x + 1, y, z; #4:
x ꢂ 1, y, z.
Synthesis of [Ni(btx)(ip)(H2O)] (1)
The mixture of NiCl2ꢁ6H2O (0.0475 g, 0.2 mmol), isophthalic
acid (0.0332 g, 0.2 mmol), and btx (0.048 g, 0.2 mmol) was
dissolved in 10 mL of distilled water. The pH value was then
adjusted to 6.0 with 1 M NaOH solution. The resulting solution
was transferred and sealed in a 25 mL Teflon-lined stainless steel
vessel and heated at 160 °C for 2 days. The green crystals were
obtained after the reaction system was slowly cooled to room
temperature. The yield was 0.065 g (68%). Anal. Calcd. for
Table 3
Selected bond distances (Å) and angles (°) for compound 2.
Co(1)–O(1)#1
Co(1)–N(1)#1
2.071(2)
2.129(3)
98.87(9)
81.13(9)
81.13(9)
98.87(9)
88.35(11)
91.65(11)
Co(1)–O(2)#2
2.091(2)
O(1)–Co(1)–O(2)#2
O(1)#1–Co(1)–O(2)#2
O(1)–Co(1)–O(2)#3
O(1)#1–Co(1)–O(2)#3
O(1)–Co(1)–N(1)
O(1)#1–Co(1)–N(1)
O(2)#2–Co(1)–N(1)
O(2)#3–Co(1)–N(1)
O(1)–Co(1)–N(1)#1
O(1)#1–Co(1)–N(1)#1
O(2)#2–Co(1)–N(1)#1
O(2)#3–Co(1)–N(1)#1
88.14(11)
91.86(11)
91.65(11)
88.35(11)
88.47(10)
88.14(11)
C
20H18N6NiO5 (%): C, 49.93; H, 3.77; N, 17.47. Found: C, 49.70;
H, 3.88; N, 17.20. IR (KBr, cmꢂ1): 3413(m), 3120(w), 1607(m),
1525(s), 1479(w), 1440(w), 1404(m), 1372(s), 1283(w), 1134(m),
1022(w), 744(w), 721(m), 676(w).
Symmetry transformations used to generate equivalent atoms: #1: ꢂx, ꢂy + 1,
ꢂz + 2; #2: x ꢂ 1, y, z; #3: ꢂx + 1, ꢂy + 1, ꢂz + 2.
Preparation of [Co(btx)(ox)]ꢁ2H2O (2)
(KBr, cmꢂ1): 3479(m), 3137(w), 1618(s), 1520(m), 1440(w),
1358(w), 1314(w), 1274(w), 1119(m), 1014(m), 992(w), 806(w),
735(w), 680(w), 491(w).
A mixture of CoCl2ꢁ6H2O (0.0476 g, 0.2 mmol), (NH4)2C2O4ꢁH2O
(0.0284 g, 0.2 mmol), and btx (0.048 g, 0.2 mmol) was dissolved in
10 mL of distilled water and then was stirred in room temperature
for 0.5 h. The resulting solution was sealed in a 25 mL Teflon-lined
stainless steel vessel and heated at 160 °C for 2 days and then
slowly cooled to room temperature. Orange-yellow crystals suit-
able for X-ray diffraction analysis were obtained when the reactor
was cooled to room temperature from reaction temperature. The
yield was 0.049 g (58%). Anal. Calcd. for C14H16CoN6O6 (%): C,
39.73; H, 3.81; N, 19.86. Found: C, 39.68; H, 3.76; N, 19.83. IR
Crystal structure determination and refinement
The single crystal structure data for compounds 1 and 2 were
collected on a Bruker SMART1000 CCD with graphite monochro-
matic Mo K
a radiation (k = 0.71073 Å) at room temperature. The
structures were solved by direct method with SHELXS-97 program