Syntheses and crystal structures of two new complexes with 5-bromoisophthalate and bis(imidazole) ligands

Article abstract of DOI:10.1080/15533174.2011.609219

Two new complexes, [Cu(5-Br-ip)(biim-5)]_n (1) and [Ni(5-Brip)₂(biim-4)]_n (2) [ 5-Br-H₂ip=5- bromoisophthalate; biim-4=1,4- bis(imidazol)butane; biim-5 = 1,5-bis(imidazole)pentane], have been synthesized via hydrothermal reactions and characterized by elemental analysis and single-crystal x-ray analysis. Complex 1 belongs to the monoclinic system, P2(1)/c space group, a = 7.6055(19) A, b=25.860(6) A, c=10.075(3) A, β =96.585(3)°, F (000)=1028, R₁ = 0.0327, _wR₂ = 0.0820; Complex 2 belongs to the triclinic system, P-1 space group, a = 9.4766(12) A, b = 11.5781(14) A, c = 14.1063(17) A, a = 73.5900(10)°, β = 71.8470(10)°, ? = 74.337(2)°, F (000) = 736, R₁ = 0.0662,_wR₂ = 0.1626. In complex 1, the 5-Br-ip ligand takes the bidentate-bridging and bidentate-chelatingmodes to bridge the neighboring Cu(II) ions to yield a one-dimensional (1D) double chain with dinuclear Cu units. However, the 5-Br-ip ligand takes the bidentate- bridgingmodes to bridge the neighbouring Ni(II) ions to yield a 1D chain in complex 2. Both 1D chains in 1 and 2 are connected by biim-5 or biim-4 to form an infinite two-dimensional (2D) layer. Copyright Taylor & Francis Group, LLC.

Full text of DOI:10.1080/15533174.2011.609219

Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 41:1358–1363, 2011
Copyright ꢀ Taylor & Francis Group, LLC
C
ISSN: 1553-3174 print / 1553-3182 online
DOI: 10.1080/15533174.2011.609219
Syntheses and Crystal Structures of Two New Complexes
with 5-Bromoisophthalate and Bis(imidazole) Ligands
Jian-Hua Qin, Jian-Ge Wang, Ke-Yan Zhao, and Yue Hu
College of Chemistry and Chemical Engineering, Luoyang Normal University, Luoyang, P. R. China
been well investigated. 1,4-Bis(imidazol)butane (biim-4) and
1,5-bis(imidazole)pentane (biim-5), bearing a longer methylene
( CH2 )4 or ( CH2 )5 skeleton, are good candidates for N-
donor linkers.[14–20] The flexible nature of the ( CH2 )4 or
( CH2 )5 spacer allows the molecules to bend and rotate freely
when binding to metal centers so as to conform to the coordina-
tive geometries of metal ions. In addtion, 5-bromoisophthalate
(5-Br-H2ip) may serve as a suitable building block to construct
novel coordination polymers due to the existence of a noncoor-
dinating electron-withdrawing Br group on the aromatic back-
bone, which will have a profound impact on the electron density
of such a ligand and therefore different physical and chemical
properties. In this contribution, 5-Br-H2ip, biim-4, and biim-
5 are selected to react with Cu(II) and Ni(II) ions to obtain
new MOFs. Herein, the syntheses and x-ray crystal structures
of two coordination networks, [Cu(5-Br-ip)(biim-5)]n (1) and
[Ni(5-Br-ip)2(biim-4)]n (2), are reported.
Two new complexes, [Cu(5-Br-ip)(biim-5)]n (1) and [Ni(5-Br-
ip)2(biim-4)]n (2) [ 5-Br-H2ip = 5-bromoisophthalate; biim-4 = 1,4-
bis(imidazol)butane; biim-5 = 1,5-bis(imidazole)pentane], have
been synthesized via hydrothermal reactions and characterized by
elemental analysis and single-crystal x-ray analysis. Complex 1 be-
longs to the monoclinic system, P2(1)/c space group, a = 7.6055(19)
Å, b = 25.860(6) Å, c = 10.075(3) Å, β = 96.585(3)◦, F (000) = 1028,
R1 = 0.0327, wR2 = 0.0820; Complex 2 belongs to the triclinic sys-
tem, P-1 space group, a = 9.4766(12) Å, b = 11.5781(14) Å, c =
14.1063(17) Å, α = 73.5900(10)◦, β = 71.8470(10)◦, γ = 74.337(2)◦,
F (000) = 736, R1 = 0.0662,wR2 = 0.1626. In complex 1, the 5-Br-ip
ligand takes the bidentate-bridging and bidentate-chelating modes
to bridge the neighboring Cu(II) ions to yield a one-dimensional
(1D) double chain with dinuclear Cu units. However, the 5-Br-ip
ligand takes the bidentate-bridging modes to bridge the neighbour-
ing Ni(II) ions to yield a 1D chain in complex 2. Both 1D chains
in 1 and 2 are connected by biim-5 or biim-4 to form an infinite
two-dimensional (2D) layer.
Keywords bis(imidazole), 5-bromoisophthalate, crystal structure,
hydrothermal synthesis
EXPERIMENTAL
Materials and Physical Measurements
All reagents used in the syntheses were of analytical grade.
Elemental analyses for carbon, hydrogen, and nitrogen were
performed on a Vario EL III elemental analyzer. The crys-
tal determination was performed on a Bruker Smart Apex II
CCD diffractometer equipped with graphite-monochromatized
MoKα radiation (λ = 0.71073 Å).
INTRODUCTION
The design and synthesis of metal-organic frameworks
(MOFs) have attracted considerable attention because of their
potential applications as function materials as well as their
structural diversity and intriguing variety of topologies.[1–6] It
is well known that carboxylate ligands play an important role
in coordination chemistry, which may adopt diverse binding
modes such as monodentate, chelating, and bridging in the
syn–syn, syn–anti, and anti–anti configurations.[7–13] So far,
a great many metal-carboxylate complexes, in the presence
of rigid N-donor bridging ligands such as 4,4ꢁ-bipyridine and
its derivatives have been designed and characterized widely.
However, metal-carboxylate complexes containing flexible N-
bridging ligands, especially bis(imidazole) ligands, have not
Syntheses of Complexes
[Cu(5-Br-ip)(biim-5)]n (1)
A mixture of 5-Br-H2ip (0.10 mmol, 24.5 mg), biim-5 (0.10
mmol, 20.4 mg), and Cu(OAc)2·H2O (0.10 mmol, 20 mg) in
distilled water (15 mL) was placed in a Teflon-lined stainless-
steel vessel, heated to 120◦C for 3 days, and then cooled to room
temperature over 24 h. Blue block crystals of 1 were obtained.
Elem. anal. (%): calcd. for C19H19BrCuN4O4 (Mr = 510.83):
C, 44.67; H, 3.75; N, 10.98; found: C, 44.58; H, 3.69; N, 10.90.
Received 9 May 2011; accepted 26 July 2011.
[Ni(5-Br-ip)2(biim-4)]n (2)
Address correspondence to Jian-Hua Qin, College of Chemistry and
Chemical Engineering, Luoyang Normal University, Luoyang 471022,
P. R. China. E-mail: jh q128105@126.com
A mixture of 5-Br-H2ip (0.20 mmol, 49 mg), biim-4 (0.10
mmol, 19 mg), and Ni(OAc)2·4H2O (0.10 mmol, 24.9 mg) in
1358

5-BROMOISOPHTHALATE AND BIS(IMIDAZOLE) LIGANDS
1359
TABLE 1
Crystallographic data for complexes 1 and 2
Compound 1
Compound 2
Empirical formula
Formula weight
Temperature (K)
Crystal system
Space group
C19H19BrCuN4O4
510.83
296(2)
Monoclinic
P2(1)/c
C26H22Br2N4NiO8
737.01
296(2)
Triclinic
P-1
a = 7.6055(19) Å
b = 25.860(6) Å
c = 10.075(3) Å
α = 90 ◦
a = 9.4766(12) Å
b = 11.5781(14) Å
c = 14.1063(17) Å
α = 73.5900(10) ◦
β = 71.8470(10) ◦
γ = 74.337(2) ◦
1382.4(3)
Unit cell dimensions
β = 96.585(3) ◦
γ = 90 ◦
V (Å3 )
1968.5(8)
Z
4
2
Dc (kg m−3
F(000)
)
1.724
1028
1.771
736
GOF
1.015
1.032
Crystal size (mm3)
0.50 × 0.22 × 0.13
2.57∼25.50
14772
0.36 × 0.24 × 0.23
2.43∼25.50
10587
θ range for data collection (◦)
Reflections collected
Independent reflections
Final R indices (I > 2σ(I))
R indices (all data)
Largest diff. peak and hole (e Å−3
3662(Rint = 0.0335)
R = 0.0327, wR2 = 0.0820
R = 0.0452, wR2 = 0.0899
1.160 and −0.364
5109 (Rint = 0.0271)
R = 0.0662, wR2 = 0.1626
R = 0.0879, wR2 = 0.1773
2.972 and –3.063
)
–3.063 e/Å3 for 2. Table 1 shows the crystallographic crystal
data of 1 and 2, and Table 2 shows their selected bond lengths
and bond angles.
distilled water (15 mL) was placed in a Teflon-lined stainless
steel vessel, heated to 120◦C for 3 days, and then cooled to room
temperature over 24 h. Green block crystals of 1 were obtained.
Elem. anal. (%): calcd. for C26H22Br2N4NiO8 (Mr = 736.98):
C, 42.37; H, 3.01; N, 7.60; found: C, 42.28; H, 2.94; N, 7.52.
Crystallographic Data Collection and Structures
Determination
Single-crystal x-ray diffraction analyses of the two com-
plexes were carried out on a Bruker Smart Apex II CCD diffrac-
tometer equipped with a graphite-monochromated Mo Kα radi-
ation (λ = 0.71073Å) by using the φ/ω scan technique at room
temperature. The structures were solved by direct methods with
SHELXS-97.[21] Empirical absorption corrections were applied
with the SADABS program.[22] All non-hydrogen atoms were
refined anisotropically. The hydrogen atoms were assigned with
common isotropic displacement factors and included in the final
refinement by use of geometrical restrains. A full-matrix least-
squares refinement on F2 was carried out using SHELXL-97.[23]
The final R = 0.0327, wR = 0.0820 (w = 1/[σ2(Fo2) + (0.0355P)2
+ 2.0850P], where P = (F2o + 2Fc2)/3), S = 1.015, ( ρ)max
=
1.160, and ( ρ)min = –0.364 e/Å3 for 1; and R = 0.0662, wR
= 0.1626 (w = 1/[σ2(Fo2) + (0.0673P)2 + 0.4338P], where P
= (F2o + 22c)/3), S = 1.032, ( ρ)max = 2.972, and ( ρ)min
=
FIG. 1. Coordination environment of the Cu(II) ion in 1.

1360
Bond
J.-H. QIN ET AL.
TABLE 2
Selected bond lengthsa (Å) and bond angles (◦) for 1 and 2
Compound 1
Distance
Bond
Cu(1)-O(1)
Cu(1)-O(3)#3
Cu(1)-O(2)
Distance
Cu(1)-N(4)#1
Cu(1)-N(1)
Cu(1)-O(4)#2
1.981(3)
1.986(3)
1.998(2)
2.049(2)
2.280(2)
2.555(2)
Angle
(◦)
Angle
(◦)
N(4)#1-Cu(1)-N(1)
N(4)#1-Cu(1)-O(4)#2
N(1)-Cu(1)-O(4)#2
N(4)#1-Cu(1)-O(1)
N(1)-Cu(1)-O(1)
173.14(11)
96.83(11)
88.27(10)
88.53(10)
89.35(10)
O(4)#2-Cu(1)-O(1)
N(4)#1-Cu(1)-O(3)#3
N(1)-Cu(1)-O(3)#3
O(4)#2-Cu(1)-O(3)#3
O(1)-Cu(1)-O(3)#3
149.84(9)
87.65(10)
86.46(10)
107.17(9)
102.68(8)
Compound 2
Bond
Distance
Bond
Distance
Ni(1)-O(2)
Ni(1)-O(7)#1
Ni(1)-N(1)
2.052(4)
2.054(4)
2.066(5)
Ni(1)-N(4)#2
Ni(1)-O(4)#3
Ni(1)-O(5)
2.069(5)
2.118(4)
2.117(4)
Angle
(◦)
Angle
(◦)
O(2)-Ni(1)-O(7)#1
O(2)-Ni(1)-N(1)
93.09(16)
86.13(18)
176.90(19)
177.25(18)
87.27(18)
93.6(2)
N(1)-Ni(1)-O(4)#3
N(4)#2-Ni(1)-O(4)#3
O(2)-Ni(1)-O(5)
O(7)#1-Ni(1)-O(5)
N(1)-Ni(1)-O(5)
86.60(19)
91.12(18)
96.40(17)
85.68(16)
91.42(18)
86.35(19)
176.68(17)
O(7)#1-Ni(1)-N(1)
O(2)-Ni(1)-N(4)#2
O(7)#1-Ni(1)-N(4)#2
N(1)-Ni(1)-N(4)#2
O(2)-Ni(1)-O(4)#3
O(7)#1-Ni(1)-O(4)#3
N(4)#2-Ni(1)-O(5)
O(4)#3-Ni(1)-O(5)
86.13(16)
96.35(17)
aSymmetry transformations used to generate the equivalent atoms: #1, –x + 2, y + 1/2, –z + 1/2; #2, x, y, z – 1; #3, –x + 2, –y + 2, –z + 1
for 1; and #1, –x + 1, –y + 1, –z + 1; #2, x, y + 1, z; #3, –x, –y, –z + 1 for 2.
RESULTS AND DISCUSSION
dimensional (2D) network containing noncentrosymmetric din-
uclea Cu units as nodes. As shown in Figure 1, the asymmetric
unit of 1 consists of one Cu(II) ion, one 5-Br-ip ligand, and
one biim-5 molecule. The geometry around the Cu(II) ion ap-
pears to be strong distorted octahedral, which is shown with the
Crystal Structure Description
[Cu(5-Br-ip)(biim-5)]n
The x-ray structural analysis shows that 1 crystallizes in a
monoclinic system, space group P2(1)/c and features a two-
FIG. 2. One-dimensional chain of 1 bridged by 5-Br-ip ligand.

5-BROMOISOPHTHALATE AND BIS(IMIDAZOLE) LIGANDS
1361
FIG. 3. Two-dimensional layer of 1 connected by 5-Br-ip and biim-5 ligands.
angle O1–Cu1–O2 = 56.430(74)◦. Four coordinated oxygen coordinated with two nitrogen atoms from two biim-4 molecules
atoms from three 5-Br-ip ligands occupy the equatorial basal and four oxygen atoms from four 5-Br-ip ligands. The Ni–O
plane [Cu1–O1 = 2.049(2), Cu1–O2 = 2.555(2), Cu1–O3B = and Ni–N bond lengths are in the range of 2.052(4)–2.118(4)
2.280(2), and Cu1–O4C = 1.998(2) Å], while two coordinated and 2.066(5)–2.069(5) Å, respectively, which are all within the
nitrogen atoms from two biim-5 molecules occupy the axial po- normal range generally found in the literature.[16] In 2, the 5-
sitions with an N1–Cu1–N4A angle of 173.14(11)◦. The Cu–O Br-ip ligand takes the bidentate-bridging modes to bridge the
and Cu–N bond lengths are in the range of 1.998(2)–2.555(2) neighboring Ni(II) ions to yield a 1D chain (Figure 5). Further-
and 1.9813(29)–1.9857(29) Å, respectively, which are in the more, these 1D chains are linked by biim-4 molecules to form
normal range expected for such coordination bonds.[14,18] Two O an infinite 2D sheet (Figure 6). The biim-4 molecule adopts a
atoms of each carboxylate group bridge two Cu(II) ions, and two bidentate-bridging conformation mode with the dihedral angle
such bridges form a eight-membered noncentrosymmetric din-
uclear ring with a Cu···Cu nonbonding distance of 4.6552(11)
Å. Further, such ring units are bridged by the 5-Br-ip ligands to
yield a one-dimensional (1D) double chain (Figure 2). Then the
neighboring 1D chains are linked by biim-5 molecules to form
an infinite 2D sheet (Figure 3). The biim-5 molecule adopts
a bidentate-bridging conformation mode with the dihedral an-
gle between the two imidazole rings of 86.06◦, suggesting that
these imidazole rings of each flexible ligand are almost perpen-
dicular to each other. The Cu···Cu separation across the biim-5
molecule is 13.0 Å.
[Ni(5-Br-ip)2(biim-4)]n
X-ray analysis reveals that the asymmetric unit of 2 consists
of one central Ni(II) ion, two 5-Br-ip ligands, and one biim-4
molecule. The coordination environment around the Ni(II) ion
can be described as a distorted octahedral [NiO4N2] coordi-
FIG. 4. Coordination environment of the Ni(II) ion in 2.
nation geometry (as shown in Figure 4). Each Ni(II) ion is six-

1362
J.-H. QIN ET AL.
FIG. 5. One-dimemsional chain of 2 bridged by 5-Br-ip ligand.
FIG. 6. Two-dimensional layer of 2 connected by 5-Br-ip and biim-4 ligands.
between the two imidazole rings of 21.00◦. The Ni···Ni separa- (fax: +44-1223-336-033; e-mail: deposit@ ccdc.cam.ac.uk; or
tion across the biim-4 molecule is 11.6 Å.
http://www.ccdc.cam.ac.uk).
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