Structures of hydrazones, (E)-2-(1,3-benzothiazolyl)-NHNCHAr, [Ar = 4-(pyridin-2-yl)phenyl, pyrrol-2-yl, thien-2-yl and furan-2-yl]: Difference in conformations and intermolecular hydrogen bonding

Article abstract of DOI:10.1016/j.molstruc.2012.09.058

Structures of hydrazones, (E)-2-(1,3-benzothiazolyl)-NHNCHAr(Ar = pyridine-2-yl (1), pyrrol-2-yl (2), thien-2-yl (3) and furan-2-yl (4), prepared from 2-hydrazinyl-1,3-benzothiazole and ArCHO, followed by recrystallisation from alcohol solutions, are repo

Full text of DOI:10.1016/j.molstruc.2012.09.058

Journal of Molecular Structure 1036 (2012) 19–27
Contents lists available at SciVerse ScienceDirect
Journal of Molecular Structure
journal homepage: www.elsevier.com/locate/molstruc
Structures of hydrazones, (E)-2-(1,3-benzothiazolyl)-NHAN@CHAAr,
[Ar =4-(pyridin-2-yl)phenyl, pyrrol-2-yl, thien-2-yl and furan-2-yl]: Difference
in conformations and intermolecular hydrogen bonding
Eric B. Lindgren a, Julliane D. Yoneda b, Katia Z. Leal a,c, Antônio F. Nogueira d, Thatyana R.A. Vasconcelos a,d
,
James L. Wardell e,f, , Solange M.S.V. Wardell g
⇑
a Programa de Pós-Graduação em Química, Instituto de Química, Universidade Federal Fluminense, Outeiro de São João Batista s/n°, 24020-141 Niterói-RJ, Brazil
b Departamento de Química, Instituto de Ciências Exatas, Universidade Federal Fluminense, Rua Des. Ellis Hermydio Figueira 783, 27213-415 Volta Redonda-RJ, Brazil
c Departamento de Físico-Química, Instituto de Química, Universidade Federal Fluminense, Outeiro de São João Batista s/n°, 24020-141 Niterói-RJ, Brazil
d Departamento de Química-Orgânica, Instituto de Química, Universidade Federal Fluminense, Outeiro de São João Batista s/n°, 24020-141 Niterói-RJ, Brazil
e Centro de Desenvolvimento Tecnológico em Saúde (CDTS), Fundação Oswaldo Cruz (FIOCRUZ), Casa Amarela, Campus de Manguinhos, Av. Brasil 4365,
21040-900 Rio de Janeiro-RJ, Brazil
f Chemistry Department of Chemistry, University of Aberdeen, Old Aberdeen AB24 3UE, Scotland, United Kingdom
g CHEMSOL, 1 Harcourt Road, Aberdeen AB15 5NY, Scotland, United Kingdom
h i g h l i g h t s
"
"
"
Crystal structures of (E)-2-(1,3-benzothiazolyl)-NHAN@CHAAr(Het) are reported.
Differences in the supramolecular arrangements are observed.
Calculated conformations are in agreement with crystallographic findings.
a r t i c l e i n f o
a b s t r a c t
Article history:
Structures of hydrazones, (E)-2-(1,3-benzothiazolyl)-NHAN@CHAAr(Ar = pyridine-2-yl (1), pyrrol-2-yl
(2), thien-2-yl (3) and furan-2-yl (4), prepared from 2-hydrazinyl-1,3-benzothiazole and ArCHO, followed
by recrystallisation from alcohol solutions, are reported. No significant intramolecular hydrogen bonds
are present in any of the four molecules. Different conformations were found between 2 and 3, on one
hand and for 4, on the other. Thus for 4, the oxygen atom of the furanyl ring is on the same side of the
molecule as is the sulfur atom of the benzothiazole unit, while in contrast, each of the heteroatoms of
the thienyl and pyrrole rings lies on opposite sides to the benzothiazole sulphur atom. In addition to
the conformational variations, differences are noted in the connections between molecules. Despite
the presence in each case of N(hydrazono)AH—N(benzothiazolo) intermolecular hydrogen bonds, molecules of
4 are linked into spiral chains, while molecules of 2 and 3 (and indeed all compounds having Ar = substi-
tuted phenyl) form symmetric dimers. Further intermolecular interactions, albeit weaker ones, are found
Received 1 September 2012
Received in revised form 21 September 2012
Accepted 24 September 2012
Available online 2 October 2012
Keywords:
Hydrazones
2-Hydrazinyl-1,3-benzothiazoles
Crystal structures
Supramolecular arrangements
in 2 [CAHꢀꢀN and NAHꢀꢀ
p
], 3 [CAHꢀꢀ
p
] and 4 [
p p], while dimers of 1 remain essentially free. Calculations
ꢀꢀ
carried out using the DFT(B3LYP)/6-311++G(d,p) method indicated that the conformations determined by
crystallography for 2–4 were the more stable.
Ó 2012 Elsevier B.V. All rights reserved.
1. Introduction
logical activities [1]. Most recently, the crystal structures of some
2-(1,3-benzothiazolyl)-NHAN@CHAAr, compounds, prepared from
For some time, we have been interested in structures of aryl-
NHAN@CH-aryl compounds, especially those having potential bio-
substituted benzaldehydes and 2-hydrazinyl-1,3-benzothiazole [2]
were reported. This followed on from a study by Vasconcelos and
co-workers on an evaluation of the in vitro anticancer activities
of these derivatives against three neoplastic cancer cells, namely
HL-60 (leukemia), MDAMB-435 (breast) and HCT-8 (colon) [3,see
also 4]. 1,3-Benzothiazole derivatives, in general, possess diverse
⇑
Corresponding author at: Centro de Desenvolvimento Tecnológico em Saúde
(CDTS), Fundação Oswaldo Cruz (FIOCRUZ), Casa Amarela, Campus de Manguinhos,
Av. Brasil 4365, 21040-900 Rio de Janeiro-RJ, Brazil. Tel./fax: +55 21 2552 0435.
E-mail address: j.wardell@abdn.ac.uk (J.L. Wardell).
0022-2860/$ - see front matter Ó 2012 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.molstruc.2012.09.058

20
E.B. Lindgren et al. / Journal of Molecular Structure 1036 (2012) 19–27
pharmacological activities [5], including as anti-inflammatory [6],
antitumor [7–9], analgesic [10] and antimicrobial [11] agents.
Hydrazone derivatives containing heterocyclic fragments have at-
tracted special attention due to their potential as photochromic
devices [12,13], and as recording layers in the range of 350–450 nm
[14]. Such hydrazone derivatives have also found use as ligands for
extraction of metals from environmental samples [15].
Following on from our report [2] on 2-(1,3-benzothiazolyl)-
NHAN@CHAAr, compounds, where Ar = a substituted phenyl
derivative, we now wish to report the structures of four
other (E)-2-(1,3-benzothiazolyl)-NHAN@CHAArderivatives, where
Ar = 4-(pyridin-2-yl)phenyl (1), pyrrol-2-yl) (2), thien-2-yl (3) and
furan-2-yl (4), see Fig. 1. The structural and theoretical study of
compounds, 1–4, was undertaken to ascertain whether the presence
of the additional heteroaryl group led to differences in the supramo-
lecular arrangements.
with an
D
E of 2.07 ꢁ 10ꢂ5 eV. The closeness of molecules, as ob-
served in the experimental structure, was maintained in the opti-
mized chain structure, which was not observed for the gas-phase
simulations, stressing the importance of solid state effects for
compound 4.
2.2. Molecular structures
The atom numbering schemes and atom arrangements for 1–4
are shown in Fig. 2. Selected bond geometric parameters are shown
in Table 1. Molecules 2–4 are very near planar, as shown by the tor-
sional angles and the angles between the aromatic rings. The least
overall planar molecule of the four is 1, due to the pyridine-2-yl
ring being rotated out of the plane of the rest of the molecule,
see Table 1. The orientation of the pyridine ring in 1 places N(4)
in the neighbourhood of H(15), see Fig. 2, however the N(4)—
H(15) separation, at 2.56 Å (2.47 Å, calculated), suggests at best
only a weak intramolecular hydrogen bond. In 2, the N(2)—H(4)
separation, at 2.67 Å (2.63 Å, calculated), is even longer and con-
firms the absence of aN(4)AH(4)ꢀꢀN(2) intramolecular hydrogen
bond, especially as the N(4)AH(4) bond is better sited to form an
2. Results and discussion
2.1. Preparation and solution properties
The compounds were synthesised from reactions of arenecar-
baldehydes and 2-hydrazinyl-1,3-benzothiazole following a gen-
eral method [3,16]. Compounds 1 and 4 have been previously
reported [17]. Recrystallisations of 1–4 were performed from EtOH
solutions and in each case the (E)-isomer was isolated: as has been
reported [18], both (E) and (Z) isomers of related compounds have
been detected in solution.
intermolecular N(4)AH(4)ꢀꢀ
p bond with the phenyl moiety of the
benzotriazole unit, see later. All in all, no significant intramolecular
hydrogen bond appears present in any of the four compounds.
Of interest, the orientation in 4 of the heteroaryl furan moiety,
relative to the remainder of the molecule, is different from those
in compounds 2 and 3, see Fig. 2. This has consequences for the
allowed intermolecular hydrogen bonds and the supramolecular
arrangement, see later.
The NMR spectra of 1–4 were run in DMSO-d6 solution. The
d1H(NH) values, in the range 11.86–12.28 ppm, indicate significant
deshielding, as expected for the involvement of these NH moieties
in NAH—N strong hydrogen bonding. B3LYP/6-311++G(d,p) theo-
retical calculations support this conclusion, but point strongly in
all cases to centrosymmetric dimers just as found in the solid state
for 1–3, see Section 2.3. Calculated d1H(NH) of dimers are in the
range 13.75–13.99 ppm, which is in agreement with the experi-
mental results, whereas calculated d1H(NH) of monomers are in
the range 8.32–8.64 ppm, which is far shielded in relation with
experimental values. As also will be discussed in Section 2.3, these
NAH—N hydrogen bonds in solid 4 result in the creation of chains
rather than centrosymmetric dimers. B3LYP/6-311++G(d,p) calcu-
lations indicate that chain formation in 4 is not theoretically
favoured and that pairing of molecules to give symmetric dimers
provides appreciable stability for all 1–4. Indeed the optimized
geometry for chains of 4 has the molecules too far apart from each
other, which was somewhat expected, since the calculations has
been performed on the gas-phase. Hence, it has to be concluded
that solid state effects must over-ride the thermodynamic effects
for compound 4. In an attempt to reproduce these solid state
effects, both dimer and chain crystal structures were optimized
DFT/PBE method. The obtained energies were almost identical,
2.3. Crystal structures
The only strong intermolecular interactions found in each of
1–4 are the N(1)AH(1)—N(3) hydrogen bonds, see Table 2a. While
in compounds, 1–3, these lead to symmetry related dimers, R22(8),
in the case of 4 these lead to spiral C(4) chains [19], see Figs. 3a, 4,
5a and 6a. Symmetric dimer formation was generally found
for (E)-2-(1,3-benzothiazolyl)-NHAN@CHAArcompounds (Ar =
substituted phenyl group), as previously reported [2]. Thus the sit-
uation in 4 appears unique for this series of compounds.
B3LYP/6-311++G(d,p) theoretical calculations indicated that the
H(1)—N(3) distances within the N(1)AH(1)—N(3) hydrogen bonds
in the symmetric dimers are all ca. 1.92 Å in 1–3, compared to the
solid state values determined by X-ray crystallography of 2.10(3),
2.12(2) and 2.17(3) Å.
The strong N(1)AH(1)ꢀꢀN(3) hydrogen bond is the only intermo-
lecular interaction in 1. The shortest Cg—Cg separation between
non-equivalent rings [thienyl and phenyl rings] in adjacent layers
is longer at 4.2354(15) Å than the accepted cut-off distance of
4.0 Å.
Fig. 1. Formation of compounds 1–4.

E.B. Lindgren et al. / Journal of Molecular Structure 1036 (2012) 19–27
21
Fig. 2. Atom numbering schemes and arrangements for 1–4. Probability ellipsoids are drawn at the 50% level. Hydrogen atoms are drawn as spheres of arbitrary radius.
In the case of 2, two short intermolecular contacts, namely
H(6)ꢀꢀN(2) and H(4)ꢀꢀCg(phenyl) at 2.69 Å and 3.31 Å, respectively, be-
tween molecules at x, y, z and ꢂx + 1, y ꢂ 1/2, ꢂz + 1/2 are present
calculated. Both these distances are not individually considered by
the PLATON program [20] as being significant. However, the fact that
the same pair of molecules are involved in both potential interac-
tions leads us to consider that the C(6)AH(6)ꢀꢀN(2) and N(4)AH
(4)ꢀꢀCg(phenyl) interactions contribute in combination to a positive
interaction between the symmetric dimers, generated by the
N(1)AH(1)ꢀꢀN(3) hydrogen bonds, see Fig. 4.
The symmetric dimers of 3 are linked by C(7)AH(7)ꢀꢀp(thienyl)
interactions, see Fig. 5b and Table 2. As shown in Fig. 5b, each dimer
is linked to four other dimers, while
a
combination of
p(thienyl) hydrogen
N(1)AH(1)ꢀꢀN(3) hydrogen bonds and C(7)AH(7)ꢀꢀ
bonds produces a network of rings made up from six molecules, see
Fig. 6c.
As mentioned above, the N(1)AH(1)ꢀꢀN(3) intermolecular inter-
actions in 4 generate chains of molecules, C4,arranged in helices,
see Fig. 6a, rather than the symmetric dimers found in 1–3. The
helical arrangements, in the direction of the b axis, are further

22
E.B. Lindgren et al. / Journal of Molecular Structure 1036 (2012) 19–27
Table 1
Selected geometric parameters (Å, °) for 1–4.
1
2
3
4
X-ray
B3LYP/6-
X-ray
B3LYP/6-
X-ray
B3LYP/6-
X-ray
B3LYP/6-
311++G(d,p)
311++G(d,p)
311++G(d,p)
311++G(d,p)
C(2)AN(1)
N(1)AN(2)
N(2)AC(10)
C(10)AC(11)
1.345(3)
1.370(3)
1.282(3)
1.457(3)
117.6(2)
115.7(2)
122.1(2)
176.6(2)
ꢂ2.8(3)
1.368
1.348
1.284
1.459
121.2
118.1
122.4
179.9
ꢂ0.1
1.324(3)
1.382(3)
1.269(3)
1.439(3)
113.8(2)
116.5(2)
121.8(3)
ꢂ180.0(2) ꢂ180.0
ꢂ0.1(3) 0.0
ꢂ180.0(2) ꢂ180.0
179.7(2) 180.0
1.365
1.355
1.287
1.437
121.1
118.0
121.3
1.352(3)
1.361(3)
1.278(3)
1.444(4)
115.3(2)
118.2(2)
119.5(3)
ꢂ179.9(3)
ꢂ0.4(4)
1.368
1.349
1.285
1.442
121.2
118.1
122.3
ꢂ180.0
0.0
1.333(9)
1.374(8)
1.271(9)
1.444(10)
118.3(5)
115.9(5)
120.6(6)
ꢂ178.0(7)
2.1(9)
1.368
1.348
1.285
1.440
121.1
117.9
121.4
ꢂ180.0
0.0
C(2)AN(1)AN(2)
N(1)AN(2)AC(10)
N(2)AC(10)AC(11)
N(3)AC(2)AN(1)AN(2)
S(1)AC(2)AN(1)AN(2)
C(2)AN(1)AN(2)AC(10)
N(1)AN(2)AC(10)AC(11)
N(2)AC(10)AC(11)AC(12)
N(2)AC(10)AC(11)AX
ꢂ172.5(2) ꢂ179.9
ꢂ179.2(2) ꢂ179.9
177.7(3)
180.0(3)
180.0
180.0
177.4(7)
179.5(7)
4.6(14)
180.0
180.0
0.0
ꢂ3.9(4)
ꢂ0.4
179.8
179.8
19.9
ꢂ176.6(3) ꢂ180.0
ꢂ171.8(3)a ꢂ180.0
175.5(2)b
1.7(4)c
0.0
180.0
6.9(4)d
0.0
180.0
ꢂ175.8(7)e ꢂ180.0
C(10)AC(11)AC(12)AC(13) 179.1(2)
C(15)AC(14)AC(17)AN(4) 23.7(4)
178.9(3)
178.2(3)a
ꢂ179.4(9)
ꢂ180.0
C(15)AC(14)AC(17)AC(21) ꢂ156.8(3) ꢂ159.2
Compound
Angle
Angle between best planes though the aromatic rings
1
2
3
4
3.77a/27.08(8)b
2.3(2)
4.4(2)
2.6(5)
a
b
c
C(14) instead of C(12).
X = C(16).
X = N(4).
X = S(2).
X = O(1).
d
e
Table 2
Parameters (Å, °) for the intermolecular interactionsa in 1–4.
Compound
DAHꢀꢀA
DAH
HꢀꢀA
DꢀꢀA
X-ray
DAHꢀꢀA
X-ray
Theoretical
X-ray
Theoretical
Theoretical
X-ray
Theoretical
(a) Intermolecular hydrogen bonds
1
2
3
4
N(1)AH(1)ꢀꢀN(3i)
0.93(3)
0.88(2)
0.84(3)
0.87(4)
1.059
1.038
1.038
1.038
2.10(3)
2.12(2)
2.17(3)
2.02(4)
1.925
1.934
1.934
1.936
3.020(3)
2.988(3)
2.999(4)
2.889(6)
2.981
2.967
2.968
2.970
171(3)
174(2)
176(3)
178(10)
174.8
173.0
173.3
173.0
N(1)AH(1)ꢀꢀN(3ii)
N(1)AH(1)ꢀꢀN(3iii
)
N(1)AH(1)ꢀꢀN(3iv
)
Compound
XAYꢀ ꢀ ꢀCg
Yꢀ ꢀ ꢀCg
Yperp
c
XAYꢀ ꢀ ꢀCg
Xꢀ ꢀ ꢀCg
(b) XAY—p interactions
2
3
N(4)AH(4)ꢀ ꢀ ꢀCg(3)
C(7)AH(7)ꢀ ꢀ ꢀCg(2ii)
3.31
2.89
140
144
2.83
11.41
3.697(3)
Cg(J)perp
Compound
Cg(I)ꢀꢀCg(J)
CgꢀꢀCg
a
b
c
Cg(I)perp
(c)
4
4
pꢀꢀp intermolecular contacts
Cg(1)ꢀꢀCg(3i)
3.682(4)
3.682(4)
1.8(3)
1.8(3)
19.42
18.98
18.98
19.42
3.482(3)
3.472(3)
3.472(3)
3.481(3)
Cg(3)ꢀꢀCg(1ii)
Symmetry operations: i = ꢂx, 1 ꢂ y, 1 ꢂ z; ii = 1 ꢂ x, ꢂ1 ꢂ y, ꢂz; iii = ꢂx, ꢂ1 ꢂ y, ꢂz; iv = 1 ꢂ x, 1/2 + y, 1/2 ꢂ z.
Cg1 and Cg3 are the centroids of the thiazolyl and phenyl rings, respectively; Alpha is the dihedral angle between the least squares plannes of the overlapping rings. Beta is
the angle between the vectors CgꢀꢀCg and Cg(I)perp where Cg(I)perp is the perpendicular distance of Cg(I) from the plane of ring J. Similarly
c is the angle between the vectors
CgꢀꢀCg and Cg(J)perp. Symmetry codes: (i) x, 1 + y, z; (ii) x, ꢂ1 + y, z.
a
Cg2 and Cg3 are the centroids of the thiophene and phenyl rings, respectively;
c
is the angle at H between the vectors Xꢀ ꢀ ꢀCg and Xperp.: symmetry operations: ii =
1/2 ꢂ x, 1/2 + y, ꢂz.
supported by p(thiazoly)ꢀꢀp(phenyl) stacking interactions between
alternate molecules in the chains, see Fig. 6b. There are no interac-
tions between the chains. Overall, a one-dimension array is pres-
ent. The packing of the molecules 1–4 are shown in Fig. 7.
whereas the conformer A is the most stable for 4, confirming the
crystallography findings. This type of calculation should be extre-
mely useful in predicting conformational preferences of similar
structures since the geometries obtained experimentally by X-ray
diffraction and theoretically by molecular modelling are very close
(RMS = 0.193 Å for 2, 0.319 Å 3, and 0.148 Å for 4. Fig. 8 shows the
relative energy vs. dihedral angle at PM3 level. From the lowest en-
ergy conformer, the barrier to rotation in 3 is smaller, compared
with the other two molecules. On the other hand, in direction to
2.4. Calculations on molecular conformations and hydrogen bonding
Table 3 shows the results of the ab initio B3LYP/6-311++G(d,p)
calculations. For 2 and 3, the conformer B is the most stable,

E.B. Lindgren et al. / Journal of Molecular Structure 1036 (2012) 19–27
23
Fig. 3. Compound 1. (a) Dimers generated by N(1)AH(1)—N(3) hydrogen bonds,
symmetry operations are listed in Table 2.
Fig. 5. Compound 3. (a) Dimers generated from N(1)AH(1)ꢀ ꢀ ꢀN(3) hydrogen bonds,
shown by blue dashed lines; (b) each dimer is linked by C(7)AH(7)ꢀ ꢀ ꢀp(thienyl)
interactions to four others shown as black dashed lines; (c) the combination of
N(1)AH(1)ꢀ ꢀ ꢀN(3) hydrogen bonds and C(7)AH(7)ꢀ ꢀ ꢀp(thienyl) interactions produces
a network of rings made up from six molecules. Symmetry operations are listed in
Table 2.
Fig. 4. Dimers of 2, generated by N(1)AH(1)ꢀꢀN(3) hydrogen bonds [symmetry
operations are listed in Table 2], linked by weak C(6)AH(6)ꢀꢀN(2) and
N(4)AH(4)ꢀ ꢀ ꢀp(phenyl) hydrogen bonds [C(6)AH(6)ꢀꢀN(2): d[H(6)ꢀꢀN(2)} = 2.69 Å and
[C(6)AH(6)ꢀꢀN(2)] = 133°;
N(4)AH(4)ꢀꢀ Cg = 140°).
N(4)AH(4)ꢀ ꢀ ꢀp(phenyl)
:
d(H(4)ꢀ ꢀ ꢀCg) = 3.31 Å
and
the lowest energy conformer, the barrier to rotation in 4 is the
smallest.
Despite differences in energies between conformers A and B of
each molecule, the semiempirical results are in agreement with the
ab initio calculations regarding the most stables conformations.
raphy on F254 silica-gel pre-coated sheets (Merck), using chloro-
form/methanol mixture as eluent, and visualized under UV light.
After reaction was complete, the solid product was collected and
washed successively with cold alcohol and ethyl ether. For the
structure determinations, the samples were recrystallized from
EtOH solutions.
Compound 1: (E)-2-(2-(4-(pyridin-2-yl)benzylidene)hydrazi
nyl)benzo[d]thiazole.
3. Experimental
Yield: 65%; m.p.: 258–260 °C. ESI-MS: m/z[MꢂH]ꢂ: 329.3.
3.1. General
1H NMR [300.00 MHz, DMSO-d6]d: 12.28 (1H; s; NH); 8.69 (1H;
00
0
d; J = 4.5 Hz; H3 ); 8.20 (1H; s; N@CAH); 8.18 (2H; d; J = 8.4 Hz; H3
Melting points were determined on a Fisher-Johns apparatus and
are uncorrected. Infrared spectra were recorded on a Perkin–Elmer
1420 spectrometer in KBr. Mass spectra (ESI-MS) were recorded
on a ZQ single quadrupole mass spectrometer. NMR spectra were re-
corded on a Varian Unity Plus 300 spectrometer operating at
300.00 MHz (1H) and 75.0 MHz (13C) in DMSO-d6 solutions.
0
and H5 ); 8.00 (1H; d; J = 7.8 Hz; H4 or H7); 7.88 (1H; ddd; J = 8.1,
0
0
7.8 and 2.1 Hz; H5 or H6); 7.81 (2H; d; J = 8.4 Hz; H2 and H6 );
7.77 (1H; s; H6 ); 7.46 (1H; d; J = 7.5 Hz; H7 or H4); 7.38–7.28
00
00
00
(2H; m; H4 and H5 ); 7.12 (1H; dd; J = 7.8 and 7.5 Hz; H6 or H5)
ppm.
13C NMR [75.0 MHz, DMSO-d6]d: 167.2; 155.3; 149.7; 139.5;
137.3; 135.0; 127.0; 126.0; 122.9; 121.7; 121.6; 120.4 ppm.
IR (cmꢂ1; KBr pellets): mmax 3427 (NH); 1624 (C@N).
Compound 2: (E)-2-(2-((1H-pyrrol-2-yl)methylene)hydrazinyl)
benzo[d]thiazole.
3.2. Synthesis
1,3-Benzothiazole hydrazoneswere prepared from reactions be-
tween 2-hydrazinobenzothiazole(1 mmol) and heteroaromatic
aldehydes(1 mmol) in ethanol (10 ml) at room temperature. The
progress of the reactions were monitored by thin-layer chromatog-
Yield: 62%; m.p.: 208–209 °C. ESI-MS: m/z[MꢂH]ꢂ: 241.3.
1 H NMR [300.00 MHz, DMSO-d6]d: 11.86 (1H; s; NH); 11.26
(1H; s; NH); 7.97 (1H; s; N@CAH); 7.71 (1H; d; J = 7.5 Hz; H4 or

24
E.B. Lindgren et al. / Journal of Molecular Structure 1036 (2012) 19–27
Fig. 6. Compound 4. (a) A partial helical chain, C4, of molecules generated from N(1)AH(1)ꢀ ꢀ ꢀN(3) hydrogen bonds n the direction of the b axis, shown by dashed lines; (b)
alternate molecules in the helical chains are linked by p(thiazoly)ꢀꢀp(phenyl) stacking interactions. Symmetry operations are listed in Table 2.
Fig. 7. Packing diagrams for compounds 1–4.
H7); 7.36 (1H; d; J = 7.2 Hz; H7 or H4); 7.25 (1H; dd; J = 8.1 and
Compound 4: (E)-2-(2-(furan-2-ylmethylene)hydrazinyl)benzo
7.2 Hz; H5 or H6); 7.05 (1H; dd; J = 7.8 and 7.2 Hz; H6 or H5);
[d]thiazole.
0
6.91 (1H; d; J = 1.5 Hz; H5 ); 6.44 (1H; s; H4); 6.13 (1H; dd; J = 5.4
Yield: 68%; m.p.: 197–199 °C. ESI-MS: m/z[MꢂH]ꢂ: 242.3.
0
and 2.4 Hz; H3 ) ppm.
1H NMR [300.00 MHz, DMSO-d6]d: 12.16 (1H; s; NH); 8.02 (1H;
s; N@CAH); 7.80 (1H; d; J = 1.8 Hz; H3 );7.72 (1H; d; J = 7.5 Hz; H4
or H7); 7.40 (1H; d; J = 7.2 Hz; H7 or H4); 7.28 (1H; dd; J = 8.1 and
7.2 Hz; H5 or H6); 7.09 (1H; dd; J = 7.8 and 7.2 Hz; H6 or H5); 6.83
0
13C NMR [75.0 MHz, DMSO-d6]d: 166.4; 137.7; 129.2; 127.3;
125.9; 122.0; 121.4; 121.2; 117.1; 111.9; 109.4 ppm.
IR (cmꢂ1; KBr pellets): mmax 3441 (NH); 1627 (C@N).
Compound 3: (E)-2-(2-(thiophen-2-ylmethylene)hydrazinyl)
benzo[d]thiazole.
0
0
0
(1H; d; J = 3.3 Hz; H4 ); 6.61 (1H; dd; J = 3.3 and 2.1 Hz; H5 ) ppm.
13C NMR [75.0 MHz, DMSO-d6]d: 166.8; 149.6; 144.8; 134.8;
128.8; 126.2; 121.6; 113.0; 112.4 ppm.
(E)-2-Benzothiazolylhydrazone 2-thiophenecarboxaldehyde.
Yield: 60%; m.p.: 217–219 °C. ESI-MS: m/z[MꢂH]ꢂ: 258.2.
1H NMR [300.00 MHz, DMSO-d6]d: 12.01 (1H; s; NH); 8.32 (1H;
s; N@CAH); 7.71 (1H; d; J = 7.8 Hz; H4 or H7); 7.58 (1H; d;
IR (cmꢂ1; KBr pellets): mmax 3436 (NH); 1615 (C@N).
3.3. Crystallography
0
0
J = 5.1 Hz; H5 ); 7.38–7.35 (2H; m; H3 and H7 or H4); 7.27 (1H;
0
ddd; J = 7.8, 7.2 and 1.2 Hz; H5 or H6); 7.12–7.05 (2H; m; H4 and
H6 or H5) ppm.
Data for 1–4 were obtained at 120(2) K with Mo Ka radiation by
means of the Bruker-Nonius 95 mm CCD camera kappa-goniostate
of the EPSRC crystallographic service, based at the University of
Southampton. Data collection was carried out under the control
of the program COLLECT [21] and data reduction and unit cell
13C NMR 13C[75.0 MHz, DMSO-d6]d: 166.7; 140.0; 139.3; 129.9;
128.2; 127.8; 125.9; 121.7; 121.6; 117.0 ppm.
IR (cmꢂ1; KBr pellets): mmax 3430 (NH); 1619 (C@N).

E.B. Lindgren et al. / Journal of Molecular Structure 1036 (2012) 19–27
25
Table 3
ZPE corrected energy (kcal/mol) of each conformer and
D
E between the two conformers, calculated at the B3LYP/6-311++G(d,p) level.
X
S
S
N
N
X
N
N
H
N
N
H
A
B
2
3
4
CONFORMER
A
B
A
B
A
B
Energy
E (BAA)
ꢂ678002.06
ꢂ3.65
ꢂ678005.71
ꢂ893147.87
ꢂ1.35
ꢂ893149.22
ꢂ690471.53
ꢂ690470.90
D
0.63
Fig. 8. Graph of relative energy vs. dihedral angle.
refinement were achieved with the COLLECT and DENZO [22]
programs. Correction for absorption was achieved in each case by
a semi-empirical method based upon the variation of equivalent
reflections with the program SADABS [23]. The programs ORTEP-
3 for Windows [24] and MERCURY [25] were used in the prepara-
tion of the figures. SHELXL97 [26] and PLATON [20] were used in
the calculation of molecular geometry. The structures were solved
by direct methods using SHELXS-97 [26] and fully refined by
means of the program SHELXL-97 [26]. Difference map peaks pro-
vided positions for the hydrogen atoms of the NH groups for which
the coordinates, along with isotropic displacement parameters,
were fully refined. All other hydrogen atoms were placed in calcu-
lated positions. Crystal data and structure refinement details are
listed in Table 4.
3.4. Calculations
The calculations were performed using the Gaussian 03W pro-
gram [27]. Molecular geometries of the dimers and the conformers
A and B of each monomer were fully optimized using the B3LYP/6-
311++G(d,p) level of theory. The zero-point energy correction was
applied to the obtained electronic energies. Since no imaginary

26
E.B. Lindgren et al. / Journal of Molecular Structure 1036 (2012) 19–27
Table 4
Crystal data and structure refinement.
1
2
3
4
Empirical formula
Formula weight
Temperature (K)
Wavelength (Å)
Crystal system, space group
Unit cell dimensions:
a (Å)
C
19H14N4S
C12H10N4S
242.3
C12H9N3S2
259.34
120(2)
0.71073
Monoclinic, P21/a
C12H9N3OS
243.28
120(2)
0.71073
Monoclinic, I2/a
330.4
120(2)
0.71073
Monoclinic, P21/n
0.71073
Monoclinic, P21/c
16.1124(6)
3.8329(2)
25.1692(11)
90
15.9740(7)
4.9329(2)
16.2227(9)
90
15.4451(5)
5.2707(2)
15.7305(5)
90
21.773(4)
4.6227(7)
28.001(5)
90
b (Å)
c (Å)
a
(°)
b (°)
101.272(2)
90
1524.40(12)
4, 1.440
0.22
118.102(2)
90
1127.62(9)
4, 1.427
0.268
504
116.813(2)
90
1142.88(7)
4, 1.507
0.443
536
101.082(6)
90
2200.9(6)
8, 1.468
0.279
1008
c
(°)
Volume (Å3)
Z, calculated density (Mg/m3)
Absorpt. coefficient (mmꢂ1
F(000)
)
688
Crystal size (mm)
Theta range for data collection (°) 3.01–27.62
Index ranges
0.2 ꢁ 0.05 ꢁ 0.03
0.36 ꢁ 0.18 ꢁ 0.06
3.75–27.49
ꢂ20 6 h 6 20
ꢂ6 6 k 6 6
ꢂ21 6 l 6 20
11,498
0.11 ꢁ 0.05 ꢁ 0.02
2.90–27.63
ꢂ20 6 h 6 19
ꢂ6 6 k 6 6
ꢂ20 6 l 6 20
12,536
0.28 ꢁ 0.03 ꢁ 0.01
2.91–25.00
ꢂ25 6 h 6 24
ꢂ5 6 k 6 5
ꢂ26 6 l 6 26
5635
ꢂ20 6 h 6 20
ꢂ4 6 k 6 4
ꢂ32 6 l 6 32
13,960
Reflections collected/unique
Independent reflections
3465
2589
2632
1878
[R(int) = 0.0489]
2746
[R(int) = 0.0596]
1778
[R(int) = 0.0549]
2144
[R(int) = 0.0879]
1209
Reflections observed [I > 2r(I)]
Data completion
0.985
0.997
0.989
0.964
Max. and min. transmission
Refinement method
0.9912 and 0.9529
Full-matrix least-squares on
F2
0.9972 and 0.5346
Full-matrix least-squares on
F2
Full-matrix least-squares on
F2
Full-matrix least-squares on
F2
Data/restraints/parameters
3465/0/223
1.105
2589/4/164
1.031
2632/0/160
1.095
1878/1/157
1.085
Goodness-of-fit on F2
Final R indices [I > 2
R indices (all data)
r
(I)]
R1 = 0.058
wR2 = 0.108
R1 = 0.079
R1 = 0.052
wR2 = 0.120
R1 = 0.0859
wR2 = 0.1381
0.368 and ꢂ0.292
R1 = 0.050
wR2 = 0.098
R1 = 0.069
wR2 = 0.109
0.468 and ꢂ0.343
R1 = 0.098
wR2 = 0.174
R1 = 0.158
wR2 = 0.206
0.490 and ꢂ0.400
wR2 = 0.120
Largest diff. peak and hole (e/Å3) 0.282 and ꢂ0.321
frequency was found, all the optimized structures were character-
ized as minima.
Appendix A. Supplementary material
Theoretical NMR chemical shifts were calculated using the GIAO
B3LYP/6-311++G(d,p) level of theory. The effect of solvent (DMSO)
was included using the integral equation formalism for the polar-
izable continuum model (IEFPCM) on Gaussian 03W [27].
The conformational behavior of each conformer was studied by
semiempirical calculations using the PM3 method. Scanning of
360° in the dihedral angle N2AC10AC11AC12 was performed with
an increment of 1° with full optimization at each step.
A geometry optimization was performed on the dimer and chain
crystal structures of compound 4, based on the experimental crystal
structure after refinement. The calculations were performed within
the framework of DFT using CASTEP program of Materials Studio
software [28]. The electronic structure was calculated by optimiz-
ing all the atoms of the crystal using ultrasoft pseudopotentials
within a plane wave basis with cutoff energy of 340 eV. The gener-
alized gradient approximation (GGA) were applied using the
Perdew–Burke–Ernzerhof (PBE) exchange–correlation functional
[29]. The energy tolerance, the maximum force tolerance and the
maximum displacement tolerance were 1.0 ꢁ 10ꢂ5 eV/atom,
0.03 eV/Å and 0.001 Å, respectively.
Full details of the crystal structure determinations in cif format
are available in the online version, at doi: (to be inserted) and have
also been deposited with the Cambridge Crystallographic Data
Centre with deposition numbers 895995 (compound 3), 895997
(compound 1), 895998 (compound 4) and 895999 (compound 2).
Copies of these last can be obtained free of charge on written appli-
cation to CCDC, 12 Union Road, Cambridge, CB2 1EZ, UK (Fax: +44
1223 336033); on request by email to deposit@ccdc.cam.ac.uk or
by access to http://www.ccdc.cam.ac.uk. Supplementary data asso-
ciated with this article can be found, in the online version, at
http://dx.doi.org/10.1016/j.molstruc.2012.09.058.
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