Hydrogen bonded 3D supramolecular architectures of three saccharinate salts

Article abstract of DOI:10.1007/s10870-011-0050-6

Three saccharinate salts (2-aminopyrimidine): (saccharin) (1), (4-phenylthiazol-2-amine): (saccharin) (2), and (2-methylquinoline): (saccharin) (3) were prepared and structurally characterized by X-ray crystallography. Salt 1 crystallizes in the monoclinic, space group P2(1)/c, with a = 7.1782(9) A, b = 13.5105(16) A, c = 12.2251(12) A, β = 93.3410(10)°, V = 1183.6(2) A³, Z = 4. Compound 2 crystallizes in the triclinic, space group P-1, with a = 7.4584(7) A, b = 8.6930(9) A, c = 12.9179(14) A, α = 108.952(2)°, β = 91.7510(10)°, γ = 97.2280(10)°, V = 783.57(14) A³, Z = 2. Compound 3 crystallizes in the monoclinic, space group P2(1)/c, with a = 7.781(8) A, b = 19.4209(19) A, c = 10.9719(12) A, β = 107.7390(10)°, V = 1579.2(16) A³, Z = 4. The different hydrogen bonding interaction modes of the saccharinate anions and the cations lead to 3D network structure, 3D staircase structure, and 3D ABAB layer structure for 1, 2, and 3 respectively. Despite variations in the cation shape on the aromatic N-heterocyclic compounds, there all existed strong intermolecular N-H...O(carbonyl) hydrogen bonds. In compounds 1, and 3 the N⁺-H...O interaction between the N⁺-H group of the cation and the C=O group of the saccharinate anion is the most important interaction in this family of salts. However, in 2, there was a N-H...O interaction between the amino proton and the C=O group of the saccharinate anion. At the next level, the aromatic C-H proton interacts with the sulfonyl O atom. There are also π-π interactions in compounds 1-2, there is CH₃-π interaction in 3. Under these interactions the three compounds exhibit synthons I-III respectively. These interactions are responsible for the high-yielding supramolecular assembly of N-containing aromatic bases and the saccharinate into salts.

Full text of DOI:10.1007/s10870-011-0050-6

J Chem Crystallogr (2011) 41:1085–1092
DOI 10.1007/s10870-011-0050-6
ORIGINAL PAPER
Hydrogen Bonded 3D Supramolecular Architectures
of Three Saccharinate Salts
•
Shouwen Jin Daqi Wang
Received: 27 June 2010 / Accepted: 7 March 2011 / Published online: 18 March 2011
Ó Springer Science+Business Media, LLC 2011
Abstract Three saccharinate salts (2-aminopyrimidine):
(saccharin) (1), (4-phenylthiazol-2-amine): (saccharin) (2),
and (2-methylquinoline): (saccharin) (3) were prepared and
structurally characterized by X-ray crystallography. Salt 1
crystallizes in the monoclinic, space group P2(1)/c, with
of the saccharinate anion. At the next level, the aromatic
C–H proton interacts with the sulfonyl O atom. There are
also p–p interactions in compounds 1–2, there is CH3–p
interaction in 3. Under these interactions the three com-
pounds exhibit synthons I–III respectively. These interac-
tions are responsible for the high-yielding supramolecular
assembly of N-containing aromatic bases and the saccha-
rinate into salts.
˚
˚
3
˚
a = 7.1782(9) A, b = 13.5105(16) A, c = 12.2251(12) A,
˚
b = 93.3410(10)°, V = 1183.6(2) A , Z = 4. Compound 2
crystallizes in the triclinic, space group P-1, with
˚
˚
a = 7.4584(7) A, b = 8.6930(9) A, c = 12.9179(14) A,
˚
a = 108.952(2)°, b = 91.7510(10)°, c = 97.2280(10)°,
Keywords Synthesis Á Structure characterization Á
3
V = 783.57(14) A , Z = 2. Compound 3 crystallizes in the
˚
Hydrogen bonding Á Saccharinate salt Á N-heterocyclic base
˚
monoclinic, space group P2(1)/c, with a = 7.781(8) A,
˚
˚
b = 19.4209(19) A, c = 10.9719(12) A, b = 107.7390(10)°,
3
V = 1579.2(16) A , Z = 4. The different hydrogen bonding
˚
Introduction
interaction modes of the saccharinate anions and the cations
lead to 3D network structure, 3D staircase structure, and
3D ABAB layer structure for 1, 2, and 3 respectively.
Despite variations in the cation shape on the aromatic
N–heterocyclic compounds, there all existed strong inter-
molecular N–H_O(carbonyl) hydrogen bonds. In
compounds 1, and 3 the N?–H_O interaction between the
N?–H group of the cation and the C=O group of the sac-
charinate anion is the most important interaction in this
family of salts. However, in 2, there was a N–H_O
interaction between the amino proton and the C=O group
The self-assembly of molecular species in the solid-state via
weak non-covalent interactions is a fundamental aspect of
supramolecular chemistry [1–3] and an important compo-
nent in the synthesis and manipulation of functional mate-
rials [4]. Supramolecular assemblies are often stabilized
by hydrogen bonding, p–p stacking, as well as electrostatic
interactions between ionic groups [1–5]. Nowadays, hydro-
gen bonding has been widely investigated in the area of
crystal engineering, supramolecular chemistry, material
science, and biological recognition [6–12]. The application
of intermolecular hydrogen bonds is a well known and
efficient tool to regulate the molecular arrangement in a
crystal structure [11, 12]. Through hydrogen bonds we can
form cocrystals and organic salts. In pharmaceuticals, salt
formation is often used in order to modify the properties of
the compounds [13]. Salt formation can be used to increase
or decrease solubility, to improve stability and to reduce
hygroscopicity of a drug product. There are many inter-
esting hydrogen bonded topological structures from infinite
1-D chain to 3-D supramolecular framework [14, 15].
S. Jin (&)
Faculty of Science ZheJiang A & F University,
Lin’An 311300, People’s Republic of China
e-mail: jinsw@zafu.edu.cn
D. Wang
Department of Chemistry, Liaocheng University,
Liaocheng 252059, People’s Republic of China
123

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J Chem Crystallogr (2011) 41:1085–1092
Saccharin (Hsac = C7H5SO3N, o-sulfobenzoimide or
H
1,2-benzisothioazole-3(2H)-one-1,1-dioxide) was discov-
ered more than 100 years ago and is one of the best known
and most widely used artificial sweetener. The imino
hydrogen of saccharin is acidic with pKa of 2.2. Saccharin
has been used as an acid in the pharmaceutical industry
[16, 17] and the crystal structures, physical properties such
as solubility and solution pH characteristics of several API
(active pharmaceutical ingredient) saccharinates have been
reported by Desiraju recently [18–20]. The saccharin is a
polyfunctional ligand with three hydrogen bond acceptor
(one carbonyl and two sulfonyl O atoms) and one hydrogen
bond donor (imino group NH). Metal complexes of
sac(saccharin) have received much attention due to their
physical and chemical properties [21].
N
N
H2N
O
O
H2N
S
N
H
N
N
S
S
O
O
O
O
1
2
N
H
O
N
Recently N-heterocyclic compounds have been widely
studied as building block to form supramolecular com-
pounds under the multiple hydrogen bonding action [22]. As
the N-containing heterocyclic aromatic compounds 2-ami-
nopyrimidine, 4-phenylthiazol-2-amine, and 2-methylquin-
oline may act as potentially tridentate or monodentate
ligands (NNN, NSN, and N). The binary organic salts of the
saccharin and N-containing heterocyclic aromatic com-
pounds may display the different hydrogen-bonding patterns
from the these acceptor atoms. As an extension of our study
of weak interactions (hydrogen bonding, p–p interaction,
and halogen bonding) concerning N-heterocyclic derivatives
[23–25], herein we report the preparation and structures of
three organic salts assembled from 2-aminopyrimidine (L1),
4-phenylthiazol-2-amine (L2), 2-methylquinoline (L3) and
saccharin (Scheme 1), respectively. In the present work,
three adducts (1–3) of the singly protonated ligand L1, L2 or
L3 with saccharin have been obtained. The three organic
salts are (2-aminopyrimidine): (saccharin) [(HL1)?Á(sac)-]
(1) (sac = saccharin), (4-phenylthiazol-2-amine): (saccha-
rin) [(HL2)?Á(sac)-] (2), and (2-methylquinoline): (saccha-
rin) [(HL3)?Á(sac)-] (3) (Scheme 2).
S
O
O
3
Scheme 2 The three organic salts described in this paper, 1–3
Experimental Section
Materials and Physical Measurements
The chemicals and solvents used in this work are of ana-
lytical grade and available commercially and were used
without further purification. 4-Phenylthiazol-2-amine was
prepared by the method described in the literature [26]. The
FT-IR spectra were recorded from KBr pellets in range
4,000–400 cm-1 on a Mattson Alpha-Centauri spectrom-
eter. Microanalytical (C, H, N, S) data were obtained with a
Perkin-Elmer Model 2400II elemental analyzer. Melting
points of new compounds were recorded on an XT-4
thermal apparatus without correction.
Preparation of the Compounds 1–3
H
(2-Aminopyrimidine): (saccharin) [(HL1)?Á(sac)-] (1)
O..............................
H
N
..................
O
H
N
N
N.................
H
N
......
N
H
N
H
S
To an ethanol solution (5 mL) of 2-aminopyrimidine (19 mg,
0.2 mmol) was addedsaccharin (36.6 mg, 0.2 mmol) in 10 mL
ethanol. The solution was stirred for a few minutes, then the
solution was filtered. The solution was left standing at room
temperature for several days, colorless crystals were isolated
after slow evaporation of the solution in air. The crystals were
collected and dried in air to give the title compound [HL1?Á
(sac)-] (1). Yield: 45 mg, 80.85%. m.p. 185–186 °C. Anal.
Calcd for C11H10N4O3S (278.29): C, 47.43; H, 3.59; N, 20.12;
S, 11.49. Found: C, 47.41; H, 3.47; N, 20.02; S, 11.37. Infrared
spectrum (KBr disc, cm-1): 3382s(mas(NH)), 3136s(ms(NH)),
3113m, 3064m, 2390w, 2196w, 1988w, 1692s(C=O), 1601m,
S
......
O
H
S
O
O
O
II
I
O
N
......
O
N H
S
O
III
Scheme 1 Hydrogen bond synthons discussed in this paper
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J Chem Crystallogr (2011) 41:1085–1092
1087
1557m, 1490m, 1361m, 1279s(l-asym.(SO2)), 1157vs
(l-sym.(SO2)), 781m, 740m, 682m, 636m, 608m, 540m, 480m,
440m.
All hydrogen atoms were placed in calculated positions
and their coordinates were refined using a riding model.
Further details of the structural analysis are summarized in
Table 1. Selected bond lengths and angles for the salts 1, 2,
and 3 are listed in Table 2, the relevant hydrogen bond
parameters are provided in Table 3.
(4-Phenylthiazol-2-amine): (saccharin)
[(HL2)?Á(sac)-] (2)
To a methanol solution (5 mL) of 4-phenylthiazol-2-amine
(35.2 mg, 0.2 mmol) was added saccharin (36.6 mg,
0.2 mmol) in 10 mL ethanol. The solution was stirred for
10 min, then the solution was filtered. The solution was left
standing at room temperature for several days, colorless
crystals were isolated after slow evaporation of the metha-
nol–ethanol solution in air. The crystals were dried in air to
give the title compound [HL2?Á(sac)-] (2). Yield: 61 mg,
84.86%. m.p. 206–208 °C. Anal. Calcd for C16H13N3O3S2
(359.41): C, 53.42; H, 3.61; N, 11.68; S, 17.81; Found:
C, 53.31; H, 3.49; N, 11.61; S, 17.74. Infrared spectrum
(KBr disc, cm-1): 3438s(mas(NH)), 3115s(ms(NH)), 3072m,
3012m, 2442w, 2288w, 1962w, 1684s(C=O), 1596m, 1536m,
1480m, 1333m, 1275s(l-asym.(SO2)), 1152vs(l-sym.(SO2)),
732m, 682m, 630m, 567m, 452m.
Results and Discussion
Preparation and General Characterization
2-Aminopyrimidine, 4-phenylthiazol-2-amine, and 2-meth-
ylquinoline all have good solubility in common organic
solvents, such as acetone, methyl alcohol, ethyl alcohol,
methylene chloride, methyl trichloride, and acetonitrile. The
crystals were grown by slow evaporation of the corre-
sponding polar solution at room temperature.
The preparation of the compounds 1–3 were carried out
with saccharin and the corresponding organic base in 1:1
ratio. The three compounds are not hygroscopic, and they
all crystallized without solvent molecules accompanied.
The molecular structures and their atom labelling schemes
for the three structures are illustrated in Figs. 1, 2, and 3,
respectively.
(2-Methylquinoline): (saccharin) [(HL3)?Á(sac)-] (3)
To a methanol solution (2 mL) of 2-methylquinoline
(28.6 mg, 0.2 mmol) was added saccharin (36.6 mg,
0.2 mmol) in 10 mL ethanol. The solution was stirred for
10 min, then the solution was filtered. The solution was left
standing at room temperature for several days, colorless
crystals were isolated after slow evaporation of the solution in
air. The crystals were dried in air to give the title compound
[(HL3)?Á(sac)-] (3), yield 58 mg, 88.86%. m.p. 186–188 °C
(decomp.). Elemental analysis performed on crystals exposed
to the atmosphere: Calc. for C17H14N2O3S (326.36): C, 62.50;
H, 4.29; N, 8.58; S, 9.80. Found: C, 62.45; H, 4.21; N, 8.54; S,
9.70. Infrared spectrum (KBr disc, cm-1): 3452s(mas(NH)),
3231s(ms(NH)), 3086m, 3024m, 2442w, 2296m, 1978w,
1687s(C=O), 1616m, 1596m, 1565m, 1474m, 1336m,
1277s(l-asym.(SO2)), 1237m, 1154vs(l-sym.(SO2)), 1052s,
802m, 712m, 618m, 558m, 470m.
In the preparation of the organic salts 1, 2, and 3 the
organic acids were mixed directly with the base in the
corresponding solution, which was allowed to evaporate
at ambient conditions to give the final crystalline prod-
ucts. The elemental analysis data for the three com-
pounds are in good agreement with their compositions.
The infrared spectra of the three compounds are con-
sistent with their chemical formulas determined by ele-
mental analysis and further confirmed by X-ray
diffraction analysis. In 1, and 2 it is the most basic ring
N atoms that have been protonated which fits well with
published results [29], and the saccharin moiety exists as
the anion.
The very strong and broad features at approximately
3,500–3,100 cm-1 in the IR spectra of the compounds 1, 2,
and 3 arise from N–H stretching frequencies. Aromatic and
pyrimidic and thiazolic ring stretching and bending are
attributed to the medium intensity bands in the regions
of 1,500–1,630 and 600–750 cm-1, respectively. The
stretching vibrations of l-asym.(SO2) and l-sym.(SO2)
X-ray Crystallography and Data Collection
Suitable crystals were mounted on a glass fiber on a Bruker
SMART 1000 CCD diffractometer operating at 50 kV and
occur characteristically at ca. 1,280 and 1,150 cm-1
,
˚
40 mA using Mo Ka radiation (0.71073 A). Data collection
respectively. For 1, 2, and 3 the absorption bands of the
carbonyl group of sac appear at ca. 1,690 cm-1 as a very
strong single band, which indicated that the saccharinate
salts formation have occurred (ca. 1,720 cm-1 in
saccharin).
and reduction were performed using the SMART and
SAINT software [27]. 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 [28].
123

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J Chem Crystallogr (2011) 41:1085–1092
Table 1 Summary of X-ray
crystallographic data for
complexes 1, 2, and 3
1
2
3
Formula
Fw
C11H10N4O3S
278.29
C16H13N3O3S2
C17H14N2O3S
326.36
359.41
T (K)
298(2)
298(2)
298(2)
˚
Wavelength (A)
Crystal system
Space group
0.71073
Monoclinic
P2(1)/c
7.1782(9)
13.5105(16)
12.2251(12)
90
0.71073
Triclinic
P-1
0.71073
Monoclinic
P2(1)/c
7.7811(7)
19.4209(19)
10.9719(12)
90
˚
a (A)
7.4584(7)
8.6930(9)
12.9179(14)
108.952(2)
91.7510(10)
97.2280(10)
783.57(14)
2
˚
b (A)
˚
c (A)
a (°)
b (°)
c (°)
93.3410(10)
90
107.7390(10)
90
3
˚
V (A )
1183.6(2)
4
1579.2(3)
4
Z
Dcalcd (mg/m3)
Absorption coefficient (mm-1
F(000)
1.562
1.523
1.373
)
0.284
0.361
0.221
576
372
680
Crystal size (mm3)
0.42 9 0.39 9 0.35 0.44 9 0.38 9 0.35 0.47 9 0.46 9 0.34
h range (°)
Limiting indices
2.25–25.01
-8 B h B 7
-16 B k B 16
-14 B l B 11
5823
1.67–25.02
-8 B h B 8
-10 B k B 10
-15 B l B 14
4106
2.10–25.01
-9 B h B 9
-14 B k B 23
-12 B l B 12
7852
Reflections collected
Reflections independent (Rint
Goodness-of-fit on F2
R indices [I [ 2rI]
)
2091(0.0270)
1.050
2722(0.0213)
1.028
2780(0.0584)
1.027
0.0369, 0.0882
0.0569, 0.1039
0.231, -0.305
0.0446, 0.0937
0.0767, 0.1126
0.229, -0.302
0.0522, 0.1290
0.1078, 0.1664
0.262, -0.361
R indices (all data)
˚
Largest diff. peak and hole (e A
-3
)
Structural Descriptions
Fig. 1. As expected, the protonated ligand in this com-
pound adopts an almost planar conformation with rms
˚
deviation of 0.0040 A. The sac ligand present in the
X-ray Structure of (2-Aminopyrimidine): (Saccharin)
[(HL1)?Á(sac)-] (1)
complex is roughly planar with a rms deviation of the non-
hydrogen atoms (excluding the sulfonyl O atoms) from the
The compound 1 of the composition [(HL1)?Á(sac)-] (1)
was prepared by reaction equal mol of 2-aminopyrimidine
and saccharin, in which the acidic NH of saccharin was
ionized. Compound 1 crystallizes in the monoclinic space
group P2(1)/c. Its single crystal structure shows the
expected proton transfer from the acid to the pyrimidyl
nitrogen atom, i. e. the acid protonates the adjacent hetero
nitrogen of the pyrimidine ring. Protonation of the pyrim-
idine base on N2 site is reflected in a change in bond angle.
The angle C(9)–N(4)–C(8) at unprotonated atom N4 is
117.0(2)°, while for protonated N2 the C(11)–N(2)–C(8)
angle is 120.4(2)°. This also occurs with the salt
bis(2-aminopyrimidin-1-ium) dichromate(VI) [30].
˚
best least square plane of approximately 0.0257(2) A, the
dihedral angle between the cation and the anion is 11.4(1)°.
The rms deviation of the phenyl ring and the five mem-
˚
˚
bered ring of the anion are 0.0072(3) A, and 0.0180(1) A
respectively, and the interplanar angle between the two
rings is 2.9(2)°.
One anion is bonded to one cation through one
N–H_N- and one N?–H_O hydrogen bonds to form a
heteroadduct with a R22(8) loop motif (Scheme 1). The
N–H_N- hydrogen bond is formed between the amino
proton of the cation and the sac N- group with N–N dis-
˚
tance of 2.997(3) A, which is shorter than the van der waals
?
˚
contact (3.1A) [31]. The N –HÁÁÁO interaction exists
between NH? and the carbonyl group of the sac with N–O
The asymmetric unit of 1 contains a mono-protonated
ligand (HL1? cation), and one (sac)- anion, as shown in
˚
distance of 2.631(3) A. There are p–p interactions between
123

J Chem Crystallogr (2011) 41:1085–1092
1089
˚
the neighboring heteroadducts with the closest centroid
˚
centroid separation of 3.309(2) A to form a heteroadduct
Table 2 Selected bond lengths [A] and angles [°] for compounds 1,
2, and 3
dimer. In the dimers the corresponding anion and cation of
the two heteroadducts were antiparallely arranged. The
dimers were connected by S=OÁÁÁp interaction to form a 1D
chain along the a axis direction in which the O atom is at
1
N(1)–C(1)
1.346(3)
1.346(3)
N(1)–S(1)
1.616(2)
1.352(3)
N(2)–C(11)
N(3)–C(8)
N(2)–C(8)
1.320(3)
O(1)–S(1)
1.4406(19)
1.242(3)
˚
ca. 2.995 A from the gravity center of the pyrimidine ring.
O(2)–S(1)
1.4322(19)
1.764(2)
O(3)–C(1)
This distance is similar to the distances reported for OÁÁÁp
S(1)–C(3)
C(1)–N(1)–S(1)
O(2)–S(1)–O(1)
O(1)–S(1)–N(1)
O(1)–S(1)–C(3)
O(3)–C(1)–N(1)
C(9)–N(4)–C(8)
C(9)–N(4)–C(8)
110.74(16)
114.86(12)
110.57(11)
110.72(11)
124.9(2)
2-
interaction concerning SO4
[32]. Such chains were
C(11)–N(2)–C(8)
O(2)–S(1)–N(1)
O(2)–S(1)–C(3)
N(1)–S(1)–C(3)
C(11)–N(2)–C(8)
O(3)–C(1)–C(2)
2
120.4(2)
connected in the c axis direction by C–HÁÁÁO interaction
112.20(12)
109.97(12)
97.16(11)
120.4(2)
between 3-CH of the cation and S=O of the anion with
˚
C–O distance of 3.337(2) A. Such chains were also con-
nected in the b axis direction through one N–HÁÁÁO
117.0(2)
hydrogen bond (between the amino group and the sulfonyl
˚
group with N–O distance of 2.996(3) A), and one CH–O
121.2(2)
117.0(2)
interaction (between the phenyl CH and the sulfonyl group
˚
with C–O distance of 3.432(3) A). With the assistance of
S(1)–O(1)
1.434(2)
1.626(2)
1.707(3)
1.340(4)
1.396(3)
1.247(3)
111.40(13)
110.44(15)
96.87(13)
110.8(2)
S(1)–O(2)
1.434(2)
1.755(3)
S(1)–N(1)
S(1)–C(3)
these interactions the compound displays a 3D network
structure, which is shown in Fig. 4. In this case the N?–
HÁÁÁO interaction between the cation NH? and the C=O
group is stronger than the N–HÁÁÁO hydrogen bond between
the amino proton and the sulfonyl group.
S(2)–C(8)
S(2)–C(10)
1.725(3)
N(1)–C(1)
N(2)–C(8)
1.340(3)
N(2)–C(9)
N(3)–C(8)
1.305(4)
O(3)–C(1)
O(1)–S(1)–O(2)
O(2)–S(1)–N(1)
O(2)–S(1)–C(3)
C(8)–S(2)–C(10)
C(8)–N(2)–C(9)
115.49(14)
111.07(14)
110.01(14)
90.57(15)
114.7(2)
O(1)–S(1)–N(1)
O(1)–S(1)–C(3)
N(1)–S(1)–C(3)
C(1)–N(1)–S(1)
3
X-ray Structure of (4-Phenylthiazol-2-amine): (saccharin)
[(HL2)?Á(sac)-] (2)
The structure of the anhydrous salt 2 with the composition
of [(HL2)?Á(sac)-] was evidenced by X-ray single crystal
diffraction. The asymmetric unit of 2 consists of one crys-
tallographically independent 4-phenylthiazolium-2-amine
cation, one crystallographically independent saccharinate
anion in its asymmetric unit (Fig. 2). Compound 2 crys-
tallizes in the triclinic space group P-1. Its single crystal
structure shows the expected proton transfer from the
acidic NH to the more basic hetero nitrogen atom of L2.
N(1)–C(1)
1.332(5)
1.319(4)
N(1)–S(1)
1.606(3)
1.359(4)
1.422(3)
1.756(3)
123.7(3)
111.35(17)
111.05(17)
97.02(16)
121.3(3)
N(2)–C(9)
N(2)–C(13)
O(1)–S(1)
1.427(2)
O(2)–S(1)
O(3)–C(1)
1.245(4)
S(1)–C(3)
C(1)–N(1)–S(1)
O(2)–S(1)–O(1)
O(1)–S(1)–N(1)
O(1)–S(1)–C(3)
O(3)–C(1)–N(1)
110.9(2)
C(9)–N(2)–C(13)
O(2)–S(1)–N(1)
O(2)–S(1)–C(3)
N(1)–S(1)–C(3)
O(3)–C(1)–C(2)
115.65(19)
110.44(16)
109.79(15)
124.1(3)
˚
The bond length N(3)–C(8) (1.305(4) A) is shorter than
Table 3 Hydrogen bond distances and angles in studied structures of 1, 2, and 3
˚
d(D–H) (A)
˚
˚
D–H_A
d(H_A) (A)
d(D_A) (A)
\(DHA) (°)
1
N(3)–H(3B)_N(1)#1
N(3)–H(3A)_O(1)
N(2)–H(2)_O(3)#1
2
0.86
0.86
0.86
2.14
2.16
1.77
2.997(3)
2.996(3)
2.631(3)
174
164
176
N(3)–H(3B)_O(3)#1
N(3)–H(3A)_O(3)#2
N(2)–H(2)_N(1)#2
3
0.86
0.86
0.86
2.05
1.90
2.13
2.833(3)
2.763(3)
2.970(3)
151
176
165
N(2)–H(2)_O(3)
0.86
1.78
2.636(4)
178
Symmetry transformations used to generate equivalent atoms for 1: #1 x, -y ? 1/2, z ? 1/2. Symmetry transformations used to generate
equivalent atoms for 2: #1 -x ? 1, -y, -z ? 1, #2 x ? 1, y, z
123

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J Chem Crystallogr (2011) 41:1085–1092
Fig. 1 Molecular structure of 1
showing the atomic numbering
scheme. Displacement
ellipsoids are drawn at the 30%
probability level
heterocyclic compounds, shorting of the C–NH2 bonds
has been explained by the attraction of a more electron-
accepting heterocyclic ring [22].
The angle C8–S2–C10 (90.57(15)°) is larger than the
corresponding angle in the neutral molecule (88.7(2)°) [33]
and in the salt 2-amino-4-phenylthiazole hydrobromide
monohydrate (90.17°) [34]. This may be due to the dif-
ference of the hydrogen bonding strength in the corre-
sponding compound. The dihedral angle between the
planes of the phenyl and thiazole rings in the same cation
of 2 is 22.5(3)°, which is larger than the value (19.23(6)°)
in 2-amino-4-phenylthiazole hydrobromine monohydrate.
But compound 2 is less planar than the neutral L2 in which
the dihedral angle between the phenyl ring and the thiazole
ring is (6.2(3) °). The planarity of 2 is further verified by
˚
the shorter C(9)–C(11) bond distance [1.463(4) A] in 2
˚
compared with the value of 1.506(3) A found in 2-amino-
4-phenylthiazole hydrobromine monohydrate [33].
The sac ligand is also planar with a rms. deviation of
˚
0.055(2) A, and the interplane angle between the 5-mem-
Fig. 2 The structure of 2, showing the atom-numbering scheme.
Displacement ellipsoids were drawn at the 30% probability level
bered ring and benzene ring in the same sac ion is 0.6(1)°.
˚
The rms deviation of the cation is 0.1784(6) A. The dihe-
dral angle between the cation and the anion is 5.3(2)°.
One cation and one anion form a heteroadduct by one
N?–HÁÁÁN- and one N–HÁÁÁO hydrogen bonds to generate a
R22(8) motif which is shown in Scheme 1. Although 2 has the
same hydrogen-bonded R22(8) loop motif as compound 1 and
the reported pyrimidyl saccharinate [29], the pair of donors
and acceptors are significantly different. Here N–HÁÁÁN
interaction is formed between the NH? cation and the anion
N- with N–N separation of 2.970(3) A which is similar to
˚
the N–N separation in compound 1. The N–HÁÁÁO hydrogen
bond existed between the amino proton and the carbonyl
˚
group with N–O distance of 2.763(3) A. There also exists
Fig. 3 The structure of 3, showing the atom-numbering scheme.
Displacement ellipsoids were drawn at the 30% probability level
one C–HÁÁÁOsulfonyl interaction with C–O distance of
˚
3.255(4) A, for this contact the anion and the cation also
formed a R22(9) hydrogen bonding graph set. These two
kinds of hydrogen bonding geometry were fused together
through the shared N?–HÁÁÁN- hydrogen bond. Two
˚
N(2)–C(8) (1.340(3) A). This suggests that the extent of
orbital overlap is more between the N(3) and C(8) atoms
than between N(2) and C(8) atoms. For similar 2-amino
123

J Chem Crystallogr (2011) 41:1085–1092
1091
Fig. 4 3D network structure
of 1
Fig. 5 3D staircase structure
of 2 viewed along the b axis direction
heteroadducts were joined together through p–p interaction
between the cationic phenyl ring of one heteroadduct and
the cationic thiazole ring of its adjacent heteroadduct with
P2(1)/c. The crystals of a new 2-methylquinoline salt,
C10H10N?ÁC7H4SO3N-, are built up from one protonated
2-methylquinoline (?1) residue, and one saccharinate (-1)
anion. The cations and the anions are roughly planar with
˚
centroid centroid separation of 3.202(8) A to form dimers. In
˚
˚
the dimers the corresponding two pairs of ions were anti-
parallely arranged. The dimers were further connected by a
pair of C–HÁÁÁO interaction between the two anions with
rms deviations of 0.0124(2) A, and 0.0103(2) A respec-
tively. The dihedral angle between the cation and the anion
is 81.3(3)°, indicating an almost perpendicular arrangement
of both ions.
˚
C–O distance of 3.258(6) A to form a 1D staircase structure
running along the a axis direction. Such staircases were also
connected by two N–HÁÁÁO hydrogen bonds between the
amino proton of the cation and the carbonyl group of the
The cation and the anion were bonded together per-
pendicularly through the only N?–HÁÁÁO hydrogen bond,
which is different from the pyridyl saccharinates in which
there are N?–HÁÁÁO hydrogen bonding accompanied with
C–HÁÁÁO, and C–HÁÁÁN interactions [29]. The N–HÁÁÁO
hydrogen bond is formed between the NH? cation and the
˚
anion with N–O distance of 2.832(3) A to form a 3D stair-
case structure, as shown in Fig. 5.
˚
carbonyl O with N–O distance of 2.636(4) A. The distance
X-ray Structure of (2-Methylquinoline): (Saccharin)
[(HL3)?Á(sac)-] (3)
between the N1 and N2 is too great to imply N–HÁÁÁN
˚
hydrogen bond (ca. 3.325(3) A which is larger than the van
-
der waals radii of two N atom (3.10) A). The N group in
˚
Compound 3 was also prepared by reaction equal mol of
2-methylquinoline and saccharin, it is also a 1:1 adduct.
The complex 3 crystallizes in the monoclinic space group
the saccharinate is not involved in any close contact which
is different from the sildenafil saccharinate [20].
123

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J Chem Crystallogr (2011) 41:1085–1092
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Supporting Information Available
Crystallographic data for the structural analysis have been
deposited with the Cambridge Crystallographic data center,
CCDC Nos. 766263 for 1, 765443 for 2, and 765439 for 3.
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.
Acknowledgment The authors are grateful for the financial support
of the Education Office Foundation of Zhejiang Province (project No.
Y201017321) and the Zhejiang A and F University Science Foun-
dation (project No. 2009FK63).
123