Crystal and molecular structure of the 1: 2 adduct formed between N,N′-Butylenebis(imidazole) and carboxylic acid derivatives

Article abstract of DOI:10.1007/s10870-009-9606-0

Two imidazolyl derived complexes [N,N′-butylenebis(imidazole): (fumaric acid)₂ (1), and N,N′-butylenebis(imidazole): (2,4,6-trinitrophenol)₂ (2)] were prepared and structurally characterized by X-ray crystallography. Compound 1 crystallizes in the triclinic, space group P-1, with a = 5.9990(12) A, b = 8.1772(16) A, c = 10.419(2) A, α = 86.88(2)°, β = 84.73(3)°, γ = 77.03(4)°, V = 495.67(17) A³, Z = 1. For 1, two dimensional network structure is formed through imidazolium moieties forming hydrogen bonds to di-ionic carboxylate groups of fumarate chains. In the same network layers and adjacent layers, C-H???O contact also accompanies the N⁺-H???O^- hydrogen bonds, all these lead the extended architecture to show a three-dimensional lamellar structure. Compound 2 crystallizes in the triclinic, space group P - 1, with a = 7.0236(14) A, b = 8.2831(17) A, c = 12.053(2) A, α = 106.05(4)°, β = 99.13(2)°, γ = 98.84(3)°, V = 650.8(2) A³, Z = 1. In 2, two parallel imidazolium cations and two antiparallel 2,4,6-trinitrophenolate anions formed 32-membered rings through hydrogen bonding interaction, these rings extended along the c axis direction to form one dimensional railway structure. Adjacent parallel railways connect further through C-H???O hydrogen bonds between the 2-CH of the imidazole ring and the NO₂ group O atoms. These weak interactions combined, the complex showed 3D layer structure.

Full text of DOI:10.1007/s10870-009-9606-0

J Chem Crystallogr (2010) 40:87–92
DOI 10.1007/s10870-009-9606-0
ORIGINAL PAPER
Crystal and Molecular Structure of the 1:2 Adduct Formed
Between N,N0-Butylenebis(imidazole) and Carboxylic Acid
Derivatives
Shouwen Jin Æ Wenbiao Zhang Æ Daqi Wang Æ
Hongfang Gao Æ Jian Zhong Zhou Æ
Rongpo Chen Æ Xiaolei Xu
Received: 18 December 2008 / Accepted: 8 August 2009 / Published online: 16 September 2009
Ó Springer Science+Business Media, LLC 2009
Abstract Two imidazolyl derived complexes [N,N0-but-
ylenebis(imidazole): (fumaric acid)2 (1), and N,N0-butyl-
enebis(imidazole): (2,4,6-trinitrophenol)2 (2)] were
prepared and structurally characterized by X-ray crystal-
lography. Compound 1 crystallizes in the triclinic, space
dimensional railway structure. Adjacent parallel railways
connect further through C–HꢀꢀꢀO hydrogen bonds between
the 2-CH of the imidazole ring and the NO2 group O atoms.
These weak interactions combined, the complex showed 3D
layer structure.
˚
˚
group P-1, with a = 5.9990(12) A, b = 8.1772(16) A,
˚
c = 10.419(2) A, a = 86.88(2)°, b = 84.73(3)°, c =
Keywords Crystal structure ꢀ
3
N,N0-Butylenebis(imidazole) ꢀ Hydrogen bonds
˚
77.03(4)°, V = 495.67(17) A , Z = 1. For 1, two dimen-
sional network structure is formed through imidazolium
moieties forming hydrogen bonds to di-ionic carboxylate
groups of fumarate chains. In the same network layers and
adjacent layers, C–HꢀꢀꢀO contact also accompanies the N?–
HꢀꢀꢀO- hydrogen bonds, all these lead the extended archi-
tecture to show a three-dimensional lamellar structure.
Compound 2 crystallizes in the triclinic, space group P - 1,
Introduction
Nowadays, hydrogen bonding has been widely developed in
the area of crystal engineering, supramolecular chemistry,
material science, and biological recognition [1–7]. The
application of intermolecular hydrogen bonds is a well
known and efficient tool to regulate the molecular arrange-
ment in a crystal structure [6, 7]. Through hydrogen bond we
can form co-crystals and organic salts. In pharmaceuticals,
salt formation is often used in order to modify the properties
of the compounds [8]. Salt formation can be used to increase
or decrease solubility, to improve stability and to reduce
hygroscopicity of a drug product. Assemble through
hydrogen bond, there have been reported many topology
structures such as an infinite 1-D chain structure [9], and 3-D
layer structure [10].
˚
with a = 7.0236(14) A, b = 8.2831(17) A, c = 12.053(2)
˚
˚
A, a = 106.05(4)°, b = 99.13(2)°, c = 98.84(3)°, V =
3
650.8(2) A , Z = 1. In 2, two parallel imidazolium cations
˚
and two antiparallel 2,4,6-trinitrophenolate anions formed
32-membered rings through hydrogen bonding interaction,
these rings extended along the c axis direction to form one
S. Jin (&) ꢀ J. Z. Zhou ꢀ R. Chen ꢀ X. Xu
Faculty of Science, ZheJiang Forestry University,
Lin’An 311300, People’s Republic of China
e-mail: Jinsw@zjfc.edu.cn; jinsw08@yahoo.cn
The carboxylic acid group is an important hydrogen
bonding functional group in crystal engineering [11]. Car-
boxylic acids aggregate in the solid state as dimer, catemer,
and bridged motifs [12–14]. Thus, it is interesting to carry
out premeditated crystal design not only with carboxylic
acids [14], but, as recent trends indicate, by exploiting
the robust and directionary recognition of carboxylic acids
with N-heterocyclic moieties [15–17]. In this context,
4,40-bipyridine [9, 18, 19], phenazine [20–22], 2-pyridone
W. Zhang
School of Engineering, ZheJiang Forestry University,
Lin’An 311300, People’s Republic of China
D. Wang
Department of Chemistry, Liaocheng University,
Liaocheng 252059, People’s Republic of China
H. Gao
Middle School of JinShan, Shanyin Road, 1268 XiaoShan,
Hangzhou, ZheJiang 311203, People’s Republic of China
123

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J Chem Crystallogr (2010) 40:87–92
O
1373s, 1284m, 1167m, 1090m, 983m, 842m, 759m, 648m,
513m.
NO2
OH
NO2
2,4,6-trinitrophenol
HO
O2N
OH
N
N
N
N
O
N,N0-Butylenebis(imidazole): (2,4,6-Trinitrophenol)2 (2)
1,4-di(1H-imidazol-1-yl)butane
fumaric acid
N,N0-butylenebis(imidazole) (0.019 g, 0.1 mmol) was dis-
solved in 1 mL of methanol. To this solution was added
2,4,6-trinitrophenol (0.046 g, 0.2 mmol) in 10 mL metha-
nol. Pale yellow block crystals were afforded after several
hours, yield 39 mg, 60%. mp 258–260 °C. Elemental
analysis performed on crystals exposed to the atmosphere:
Calc. for C22H20N10O14: C 40.71, H 3.08, N 21.59. Found:
C 40.68, H 3.07, N 21.55. Infrared spectrum (KBr disc,
cm-1): 3446m, 3146m, 3060m, 2957m, 2848m, 1614s,
1561s, 1546s, 1526s, 1484s, 1435m, 1364s, 1316s, 1274s,
1165m, 1076m, 914m, 786m, 767m, 747m, 706m, 625m,
539m.
Scheme 1 Hydrogen bond synthons discussed in this paper
[23–25], and imidazole derivatives [26, 27] have emerged as
important complementary ligands for the crystal engineering
of carboxylic acids. When carboxylic acids interact with
Im(imidazoles) and Bzim(benzimidazoles) the solid-state
outcome is often an organic salt, not a co-crystal, as a result
¨
of proton transfer [28–33]. Aakeroy [34] reported direct
assemble of ditopic imidazoles/benzimidazoles and dicar-
boxylic acids into co-crystals via selective O–HꢀꢀꢀN hydro-
gen bonds. For we are interested in the crystal engineering
assembling through weak interaction [35, 36], here in we
report the crystal structure of two complexes assembled
through hydrogen bonding interactions.
X-Ray Crystallography
In this study, we get two organic complexes composed of
carboxylic acids and symmetric ditopic bis-imidazol-1-yl
compounds (Scheme 1), namely N,N0-butylenebis(imidaz-
ole): (fumaric acid)2 (1), and N,N0-butylenebis(imidazole):
(2,4,6-trinitrophenol)2 (2).
Suitable crystals were mounted on a glass fiber on a Bruker
SMART 1000 CCD diffractometer operating at 50 kv and
˚
40 mA using Mo Ka radiation (0.71073 A). Data collection
and reduction were performed using the SMART and
SAINT software [38]. 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 [39].
Experimental Section
Hydrogen atom positions for all of the structures were
located in a difference map and refined independently.
Further details of the structural analysis are summarized in
Table 1. Selected bond lengths and angles for complexes 1
and 2 are listed in Table 2, the relevant hydrogen bond
parameters are provided in Table 3.
Materials and Methods
All reagents were commercially available and used as
received. N,N0-butylenebis(imidazole) was prepared as
described previously [37]. The C, H, and N microanalysis
were carried out with a Carlo Erba 1106 elemental ana-
lyzer. The FT-IR spectra were recorded from KBr pellets in
range 4,000–400 cm-1 on a Mattson Alpha-Centauri
spectrometer. Melting points of new compounds were
recorded on an XT-4 thermal apparatus without correction.
Results and Discussion
Preparation and General Characterization
N,N0-butylenebis(imidazole) has good solubility in com-
mon organic solvents, such as CH3OH, C2H5OH, CH3CN,
CHCl3, and CH2Cl2. The crystals were grown by slow
evaporation of the corresponding solution at room tem-
perature. Crystallization of N,N0-butylenebis(imidazole)
with fumaric acid or picric acid were carried out in a 1:2
ratio. The two complexes are not hygroscopicity, and they
all crystallized with no solvent molecules accompanied.
The molecular structures and their atom labelling schemes
for the two structures are illustrated in Figs. 1, 3.
Preparation of the Complexes
N,N0-Butylenebis(imidazole): (Fumaric Acid)2 (1)
N,N0-Butylenebis(imidazole) (0.019 g, 0.1 mmol) was
dissolved in 1 mL of ethanol. To this solution was added
fumaric acid (0.024 g, 0.2 mmol) in 3 mL ethanol. Col-
orless prisms were afforded after 1 week of slow evapo-
ration of the solvent, yield 24 mg, 55.8%. mp 209–210 °C.
Elemental analysis performed on crystals exposed to the
atmosphere: Calc. for C18H22N4O8: C 51.14, H 5.21, N
13.26. Found: C 51.07, H 5.16, N 13.22. Infrared spectrum
(KBr disc, cm-1): 3427s, 3131s, 1642s, 1621s, 1455 m,
In the preparation of 1, and 2, the acids were mixed
directly with the base in methanol and/or ethanol solution,
which was allowed to evaporate at ambient conditions to
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J Chem Crystallogr (2010) 40:87–92
89
Table 1 Summary of X-ray
crystallographic data for
complexes 1–2
1
2
Formula
Fw
C10H16N4,C4H4O4,C4H2O4
422.40
C10H16N4,2(C6H2N3O7)
648.48
T (K)
293(2)
293(2)
˚
Wavelength (A)
Crystal system
Space group
0.71073
0.71073
Triclinic
Triclinic
P - 1
P - 1
˚
a (A)
5.9990(12)
8.1772(16)
10.419(2)
86.88(2)
7.0236(14)
8.2831(17)
12.053(2)
106.05(4)
99.13(2)
˚
b (A)
˚
c (A)
a (°)
b (°)
c (°)
84.73(3)
77.03(4)
98.84(3)
3
˚
V (A )
495.67(17)
1
650.8(2)
Z
1
Dcalcd (Mg/m3)
Absorption coefficient (mm-1
F(000)
1.415
1.655
)
0.113
0.141
222
334
Crystal size (mm3)
0.50 9 0.36 9 0.16
3.17–27.52
-7 B h B 7
-10 B k B 10
-13 B l B 13
4,927
0.36 9 0.24 9 0.07
3.00–26.00
-8 B h B 8
-10 B k B 10
-13 B l B 14
5,709
h range (°)
Limiting indices
Reflections collected
Reflections independent (Rint
Goodness-of-fit on F2
R indices [I [ 2r(I)]
R indices (all data)
)
2,257 (0.0151)
1.058
2,554 (0.0263)
1.064
0.0405, 0.1248
0.0512, 0.1312
0.195, -0.285
0.0442, 0.1061
0.0667, 0.1184
0.183, -0.238
-3
)
˚
Largest diff. peak and hole (e A
give the final crystalline products. The elemental analysis
data for the compounds are in good agreement with their
compositions. The infrared spectra of 1 and 2 are consistent
with their chemical formulas determined by elemental
analysis and further confirmed by X-ray diffraction analy-
sis. The very strong and broad features at approximately
3,400–3,200 cm-1 in the spectra of the two compounds
arise from O–H or N–H stretching frequencies. Aromatic
and imidazolyl ring stretching and bending are attributed to
the medium intensity bands in the regions of 1,500–
1,630 cm-1 and 600–750 cm-1, respectively. The intense
peak at 1,642 cm-1 was derived from the existence of the
C=O stretches, and the band at 1,284 cm-1 exhibited the
presence of the C–O stretches of the fumarate. The absence
of bands at ca. 2,500 cm-1 and 1,900 cm-1 in compound 1,
and 2, was interpreted as a lack of co-crystal formation [40].
IR spectroscopy has also proven to be useful for the
recognition of proton transfer compounds [41, 42]. The
most distinct feature in the IR spectrum of proton transfer
compounds is the presence of strong asymmetrical and
symmetrical stretching frequencies at 1,550–1,610 cm-1
and 1,300–1,420 cm-1 in compound 2, respectively [43].
X-Ray Structure of N,N0-Butylenebis(imidazole):
(Fumaric Acid)2 1
The asymmetric unit of 1 consists of half a molecule of
N,N0-butylenebis(imidazole), one half of fumaric acid and
one half of a fumarate ion, which is shown in Fig. 1. Only
one N atom of 1-(4-(1H-imidazol-1-yl)-butyl)-1H-imidaz-
ole is protonated by fumaric acid. In the compound, there
are two pairs of ion pair with no included solvent mole-
cules, which is well agreement with the micro-analysis
results.
The N(1)–O(4)#4(Symmetry code 4: x ? 1, y, z) dis-
´
˚
tance in these contacts is 2.626 (2) A, which is consider-
ably less than the sum of the van der Waals radii for N and
´
˚
O (3.07 A) [44], so in the solid state, there is consistently
ionic hydrogen bonds formed between the imidazolium
NH? and the fumarate ions, which is to be expected [45].
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J Chem Crystallogr (2010) 40:87–92
˚
Table 2 Selected bond lengths [A] and angles [°] for 1–2
1
N(2)–C(1)
1.3244(17) N(2)–C(3)
1.3749(18)
1.3181(18)
1.2041(18)
1.2624(17)
108.39(12)
126.55(12)
108.75(12)
N(2)–C(4)
1.4718(16) N(1)–C(1)
N(1)–C(2)
1.3616(19) O(1)–C(6)
O(2)–C(6)
1.3025(17) O(3)–C(8)
O(4)–C(8)
1.2471(17) C(1)–N(2)–C(3)
125.04(12) C(3)–N(2)–C(4)
108.93(12) N(1)–C(1)–N(2)
C(1)–N(2)–C(4)
C(1)–N(1)–C(2)
2
N(1)–C(1)
1.319(3)
1.329(3)
1.476(3)
1.222(2)
1.224(2)
1.446(3)
1.228(2)
1.254(2)
N(1)–C(2)
N(2)–C(3)
N(3)–O(3)
N(3)–C(10)
N(4)–O(5)
N(5)–O(6)
N(5)–C(6)
C(1)–N(1)–C(2)
1.365(3)
1.370(3)
1.212(2)
1.459(2)
1.228(2)
1.216(2)
1.453(3)
108.65(19)
129.06(17)
N(2)–C(1)
Fig. 1 The structure of 1, showing the molecular components and
atom numbering scheme. Displacement ellipsoids are drawn at the
30% probability level
N(2)–C(4)
N(3)–O(2)
N(4)–O(4)
N(4)–C(8)
˚
carboxylic acid group (0.098 A) is much greater than the one
˚
found in the fumarate anions (0.0153 A). Also the average
˚
distances for C–O(1.2548 A) in fumarate is less than the
˚
single bond C–O(1.3025 A) and greater than the double bond
N(5)–O(7)
O(1)–C(11)
C(1)–N(2)–C(3)
C(3)–N(2)–C(4)
108.50(17) C(1)–N(2)–C(4)
122.43(17) O(3)–N(3)–O(2) 124.03(18)
˚
C=O(1.2041 A) in carboxylic acid group of fumaric acid.
O(3)–N(3)–C(10) 117.89(17) O(2)–N(3)–C(10) 118.07(17)
O(4)–N(4)–O(5) 122.23(18)
This supports our assignment of the fumarate anions. C–O
˚
distances (O(4)–C(8), 1.2471(17) A) clearly indicate that the
acid moieties in the compound are dianions when it formed
hydrogen bonds with the imidazoliun nitrogen atoms. So the
-
negative charge in CO2 group is localized on O(4) atom.
-
Table 3 Hydrogen bond distances and angles in studied structures 1–2
Whereas the corresponding distances for CO2 ꢀꢀꢀHOOC
´
˚
(O(2)–C(6), 1.3025(17) A) support the existence of non-
D–HꢀꢀꢀA
d(D–H) d(HꢀꢀꢀA) d(DꢀꢀꢀA) \(DHA)
˚ ˚ ˚
[A]
[A]
[A]
[°]
ionic acid moieties indicating co-crystal formation. The
significant difference in O–C bond distances of the com-
pound is mainly because of the fact that O(2) is involved in
stronger hydrogen bonding with O(3) of fumarate compared
to O(4) which is involved with hydrogen bonding of N?–
HꢀꢀꢀO- of the imidazole moiety. In the structure, there are
1
N(1)–H(2)ꢀꢀꢀO(4)#4
0.86(2) 1.77(2)
2.626(2) 170.9(2)
O(2)–H(10)ꢀꢀꢀO(3)#4 0.99(2) 1.52(2)
2.504(2)
173(2)
2
N(1)–H(10)ꢀꢀꢀO(7)#2 0.88(3) 2.39(3)
N(1)–H(10)ꢀꢀꢀO(1)#2 0.88(3) 1.88(3)
2.988(3)
2.699(3)
126(2)
155(2)
-
chains of fumarate moieties linked via CO2 ꢀꢀꢀHOOC
hydrogen bonds in which the two carboxylate O(C=O) atoms
form two hydrogen bonds in bis-monodentate fashion with
the neutral fumaric acid. The fumarate also gives strong
electrostatic interactions between both charged units, the
other two fumarate O(C–O) atoms also form two hydrogen
bonds in bis-monodentate mode with the two imidazole N
atoms. While the fumaric acid only acts as double donor(OH)
to the di-ionic fumarate. Two dimensional network structure
is formed through imidazolium moieties forming hydrogen
bonds to di-ionic carboxylate groups of fumarate chains,
which is shown in Fig. 2. In the same network layers, C–
HꢀꢀꢀO contact also accompanies the N?–HꢀꢀꢀO- hydrogen
bond, which utilizes H3, H2A on imidazole ring and O3, and
Symmetry transformations used to generate equivalent atoms for 1:
#4 x ? 1, y, z
Symmetry transformations used to generate equivalent atoms for 2:
#2 x, y - 1, z
Each imidazolium NH? forms one hydrogen bond with
one oxygen atom of the fumarate ions. It was found that
protonation of the imidazole ring nitrogen atoms causes no
significant change in conformation of (1-(4-(1H-imidazol-1-
yl)butyl)-1H-imidazole) in 1 in comparison to the corre-
sponding neutral molecule (1-(4-(1H-imidazol-1-yl)butyl)-
1H-imidazole) [46]. The imidazole rings in 1 have trans-(ap)
position in respect to C5–C5a bond (angle C4–C5–C5a–C4a,
180°), which is different from the corresponding 1,10-(1,
4-butanediyl)bis(imidazolium) dihydrochloride [46]. It is
clear that the difference in bond lengths of C–O within the
-
˚
O4 on the CO2 carbonyl oxygen atom (C3ꢀꢀꢀO3, 3.379 A;
˚
C2ꢀꢀꢀO4, 3.478 A). Adjacent layers are also connected by C–
˚
HꢀꢀꢀO (C1–H1ꢀꢀꢀO3, C1ꢀꢀꢀO3, 3.244 A) contact, all these lead
the extended architecture to show a three-dimensional
lamellar structure.
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J Chem Crystallogr (2010) 40:87–92
91
Fig. 2 Infinite two-dimensional network structure of 1
Fig. 4 2D network structure of 2 viewed from the a axis
X-Ray Structure of N,N0-Butylenebis(imidazole):
(2,4,6-Trinitrophenol)2 (2)
Imidazolium cations and 2,4,6-trinitrophenolate anions
self-assembled via N?–HꢀꢀꢀO- hydrogen bonds to form bis-
2,4,6-trinitrophenolate terminated compound, and the two
terminated 2,4,6-trinitrophenolates exist in trans confor-
mation. The NꢀꢀꢀO and HꢀꢀꢀO bond lengths ranged from
Complex 2 was prepared by reaction of a methanol solution
of 2,4,6-trinitrophenol and N,N0-butylenebis(imidazole) in
2:1 ratio, which crystallizes as triclinic pale yellow crystals
in the centrosymmetric space group P-1. The structure of
2 with the atom-numbering scheme is shown in Fig. 3. The
OH groups of 2,4,6-trinitrophenol are ionized by proton
transfer to one of the imidazole moieties of N,N0-butyl-
enebis(imidazole). Both of the terminal N atoms of bis-
imidazol-1-yl are protonated. In the whole molecule there
existed an inversion center locating in the middle point of
C5 and C5A. The dihedral angles between the imidazole
ring and the benzene ring is 78.45°.
In the solid state, there is consistently hydrogen bonds
formed between the imidazolium NH?, and the 2,4,6-tri-
nitrophenolate ions. Each imidazolium NH? forms two
hydrogen bonds with two oxygen atoms of the 2,4,6-tri-
nitrophenolate ions, one is the oxygen atom of the 2,4,6-
trinitrophenolate ions, the other oxygen atom comes from
the NO2 group.
˚
˚
2.699(3) to 2.988(3) A, and from 1.88(3) to 2.39(3) A,
respectively. The N?–HꢀꢀꢀO- bond angles ranged from
126(2) to 155(2)°. These values are consistent with values
reported from a statistical analysis of N–HꢀꢀꢀO hydrogen
bonds involving imidazolium residues in forming crystal
structures [47] and from a study of N?–HꢀꢀꢀO- hydrogen
bonding in salts of imidazole with monocarboxylic acids
[48].
Two parallel imidazolium cations and two antiparallel
2,4,6-trinitrophenolate anions formed 32-membered rings
through hydrogen bonding interaction, these rings extended
along the c axis direction to form one dimensional railway
structure. Adjacent parallel railways connect further
through C–HꢀꢀꢀO hydrogen bonds between the 2-CH of the
imidazole ring and the NO2 group O atoms (C–O distance
˚
is 3.024 A) to form 2D network structure, which is shown
in Fig. 4. The 2D network further stacks into 3D layer
structure.
Supporting Information Available
Crystallographic data for the structural analysis have been
deposited with the Cambridge Crystallographic data center,
CCDC Nos. 673178 for 1, and 674979 for 2. Copies of this
information may be obtained free of charge from the
?44(1223)336-033 or Email: deposit@ccdc.cam.ac.uk or
www: http://www.ccdc.cam.ac.uk.
Acknowledgments The authors thank the Zhejiang Forestry Uni-
versity Science Foundation for financial support.
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J Chem Crystallogr (2010) 40:87–92
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