Synthesis, spectral characterization and crystal structure of 2-benzoylpyridine N(4)-cyclohexylthiosemicarbazone

Article abstract of DOI:10.1016/j.molstruc.2004.06.018

The synthesis, characterization, molecular and crystal structure of 2-benzoylpyridine N(4)-cyclohexylthiosemicarbazone is reported. IR analysis was done and NMR assignments using COSY homonuclear and HMQC heteronuclear correlation techniques were carried

Full text of DOI:10.1016/j.molstruc.2004.06.018

Journal of Molecular Structure 705 (2004) 63–70
www.elsevier.com/locate/molstruc
Synthesis, spectral characterization and crystal structure
of 2-benzoylpyridine N(4)-cyclohexylthiosemicarbazone
a
Marthakutty Joseph , V. Suni , Chandini R. Nayar ,
a
a
a,
Maliyeckal R. Prathapachandra Kurup , Hoong-Kun Fun
b
*
a
Department of Applied Chemistry, Cochin University of Science and Technology, Kochi, Kerala 682 022, India
b
X-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia
Received 8 April 2004; revised 4 June 2004; accepted 8 June 2004
Available online 17 July 2004
Abstract
The synthesis, characterization, molecular and crystal structure of 2-benzoylpyridine N(4)-cyclohexylthiosemicarbazone is reported. IR
analysis was done and NMR assignments using COSY homonuclear and HMQC heteronuclear correlation techniques were carried out. The
electronic structure of the compound was revealed by solid state reflectance studies and in chloroform solution. The infrared spectrum gives
evidence for the compound in the thione form, which is consistent with the observed bond lengths from the crystal structure. The compound
crystallizes into a monoclinic lattice with space group P2 =n: The non-coplanarity of the two benzene rings in the compound is confirmed
1
from the dihedral angles. Puckering analysis and least square planes calculations point out to chair conformation of the cyclohexyl ring.
q 2004 Elsevier B.V. All rights reserved.
1 13
Keywords: Thiosemicarbazone; 2-Benzoylpyridine; H NMR; C NMR; COSY; HMQC; Crystal structure
1
. Introduction
N(4)-substituted 2-benzoylpyridine thiosemicarbazones and
their metal complexes [11–13]. Thiosemicarbazones exist
in the tautomeric thione (A) and thiol (B) forms (Fig. 1).
The thione form acts as a neutral bidentate ligand while
the thiol form can deprotonate and act as an anionic ligand
[14]. As a part of our studies on N(4)-substituted
thiosemicarbazones [15–24], we now report the
spectral and crystal studies of 2-benzoylpyridine
N(4)-cyclohexylthiosemicarbazone (Fig. 2).
Thiosemicarbazones are thiourea derivatives and the
studies on their chemical and structural properties have
received much attention due to the widespread application
in the chemotherapeutic field [1,2]. Thiosemicarbazones,
1
2
3 4
with the general formula R R C ¼ N–NH–CS–NR R
usually react as chelating ligands with transition metal ions
by bonding through the sulphur and the hydrazinic nitrogen
atom. The group N–CyS is of considerable chemother-
apeutic interest and is responsible for the pharmacological
activity. Thiosemicarbazones of a-(N)-heterocyclic alde-
hydes and ketones possess a broad spectrum of potentially
useful chemotherapeutic activities such as antimalarial,
antibacterial, antiviral and antileishmanial activities [3,4].
We have recently reported spectral and structural studies of
copper(II) complexes of 2-benzoylpyridine N(4), N(4)-
2. Experimental
2.1. Materials
Cyclohexyl isothiocyanate (Fluka), hydrazine hydrate
Lancaster) and 2-benzoylpyridine (Lancaster) were used as
(
(
butane-1,4-diyl)thiosemicarbazone [5]. Thiosemicarba-
received. Carbon, hydrogen and nitrogen analyses were
done on a Heraeus elemental analyzer at Central Drug
Research Institute, Lucknow, India. The infrared spectra
were recorded on a Shimadzu DR 8001 series FTIR
zones derived from 2-acetylpyridine have been extensively
studied [6–10], but there are fewer reports on the studies of
*
Corresponding author. Tel.: þ91-484-2575804; fax: þ91-484-
577595.
E-mail address: mrp@cusat.ac.in (M.R.P. Kurup).
2
1
instrument as KBr pellets in the range 4000–400 cm
1
.
The H NMR, C NMR, COSY and HMQC spectra were
2
13
0022-2860/$ - see front matter q 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.molstruc.2004.06.018

64
M. Joseph et al. / Journal of Molecular Structure 705 (2004) 63–70
Table 1
Summary of crystal data and structural refinement for HL
Empirical formula
19 22 4
C H N S
Formula weight (M)
338.47
293(2)
Fig. 1. Tautomers of thiosemicarbazone.
Temperature ðTÞ (K)
˚
Wavelength (Mo Ka) (A)
Crystal system
0.71073
recorded using Bruker DRX 500, with CDCl as solvent and
3
Monoclinic
Space group
P2 =n
1
TMS as standard at Sophisticated Instruments Facility,
Indian Institute of Science, Bangalore, India. The solid state
reflectance spectrum was recorded on Ocean Optics,
SD2000 Fiber Optic Spectrometer. The electronic spectrum
in CHCl3 solution was recorded on a Shimadzu 160A
UV/Vis Spectrophotometer.
Lattice constants
˚
a (A)
˚
b (A)
6.1522(3)
17.9701(8)
16.9023(7)
90.00
c ( A˚ )
a (8)
b (8)
g (8)
94.423(1)
90.00
3
˚
Volume V (A )
1863.08(15)
4
2
.2. X-ray data collection, structure solution and refinement
Z
Calculated density
3
1.207
2
ðrÞ (mg m
)
Slow evaporation of the ligand in methanol yielded
Absorption coefficient
2
0.181
single crystals suitable for X-ray analysis. A pale yellow
crystal of HL was mounted on a glass fiber with epoxy
cement for the crystallographic study. The crystallographic
data and structure refinement parameters for the compound
at 293 K are given in Table 1. The data were collected using
a SMART CCD diffractometer equipped with graphite-
monochromated Mo Ka radiation, with a detector distance
of 5 cm and swing angle of 2358. A hemisphere of the
reciprocal space was covered by combination of three sets
of exposures. Each set had a difference of angle (0, 88, 1808)
and each exposure of 10 s covered 0.38 in v: The structures
1
ðmÞ (mm
)
Fð000Þ
720
Crystal size (mm)
0.86 £ 0.38 £ 0.32
2.42–28.30
Q Range for data collection
Limiting indices
27 ¼ h ¼ 8; 219 ¼ k ¼ 23;
2
22 ¼ l ¼ 21
Reflections collected
Unique reflections
4559
3581 ðR ¼ 0:0169Þ
int
Completeness to u
Max. and min. transmission
Refinement method
28.29 (91.1%)
0.9444 and 0.8599
Full-matrix least-squares on F
4559/0/297
2
Data/restraints/parameters
2
Goodness-of-fit on F
1.047
were solved by direct methods and refined by least-square
2
Final R indices ðI . 2sðIÞÞ
R indices (all data)
R ¼ 0:0452; wR ¼ 0:1228
1
2
on F using the SHELXTL software package [25]. The
0
R ¼ 0:0587; wR ¼ 0:1374
1
2
collected data were reduced using SAINT program [26] and
the empirical absorption were carried out using the SADABS
program. The graphics tool was PLATON for windows [27].
All the hydrogen atoms were fixed geometrically and treated
as riding on their parent C and N atoms, with C–H distances
Largest difference peak
2
0.298 and 20.233
3
˚
and hole (eA
)
(0.250 g, 5 mmol), each dissolved in 10 ml methanol were
mixed with constant stirring. The stirring was continued for
30 min and the white product, N(4)-cyclohexylthiosemicar-
bazide formed was washed with methanol and dried.
A solution of the N(4)-cyclohexylthiosemicarbazide
˚
in the range 0.87–1.08 A. The non-hydrogen atoms were
refined with anisotropic thermal parameters. The selected
bond lengths and bond angles are listed in Table 2.
(0.865 g, 5 mmol) in 10 ml methanol was refluxed with a
2
.3. Synthesis of HL
Table 2
˚
Selected bond lengths (A) and bond angles (8) of HL
.
The thiosemicarbazone (HL) was prepared by adopting
the reported procedure of Klayman [28]. Cyclohexyl
isothiocyanate (0.706 g, 5 mmol) and hydrazine hydrate
C(1)–C(6)
C(5)–C(6)
C(6)–N(1)
C(7)–N(1)
C(7)–S(1)
C(7)–N(2)
N(2)–N(3)
C(8)–N(3)
C(8)–C(14)
C(8)–C(9)
C(9)–N(4)
C(10)–N(4)
C(9)–C(13)
C(14)–C(15)
C(14)–C(19)
1.499(3)
1.525(2)
1.452(19)
1.328(19)
1.675(15)
1.364(18)
1.367(17)
1.290(18)
1.489(2)
1.488(2)
1.345(2)
1.337(2)
1.391(2)
1.393(2)
1.384(2)
N(1)–C(6)–C(5)
N(1)–C(6)–C(1)
C(6)–N(1)–C(7)
N(1)–C(7)–S(1)
N(2)–C(7)–S(1)
N(1)–C(7)–N(2)
N(2)–N(3)–C(8)
N(3)–C(8)–C(9)
C(9)–C(8)–C(14)
N(4)–C(9)–C(8)
C(8)–C(9)–C(13)
N(4)–C(9)–C(13)
C(8)–C(14)–C(19)
C(8)–C(14)–C(15)
C(15)–C(14)–C(19)
109.43(14)
111.57(15)
125.92(13)
125.62(11)
118.87(11)
115.51(13)
120.14(12)
126.94(13)
118.95(12)
118.25(13)
120.04(14)
121.62(14)
119.82(13)
121.17(14)
118.99(14)
Fig. 2. Structure of compound N(4)-cyclohexylthiosemicarbazone (HL).

M. Joseph et al. / Journal of Molecular Structure 705 (2004) 63–70
65
methanolic solution of 2-benzoylpyridine (0.916 g, 5 mmol)
continuously for 5 h after adding 1–2 drops of acetic acid.
On cooling the solution pale yellow crystals separated,
which were filtered and washed with methanol. The crystals
were recrystallised from ethanol and dried over P O in
4
10
vacuo. (m.p. 170 8C). Yield 1.425 g (80%). The empirical
formula given for the compound C N H S was confirmed
1
9 4 22
by elemental analysis: found (calcd): C, 67.63 (67.45); H,
6
.70 (6.50); N, 16.54 (16.57).
Fig. 4. IR spectrum of HL.
3
. Results and discussion
multiplicities and coupling constants and connectivity
1
1
1
3
.1. Spectral studies
from H and H– H correlation experiments [31,34].
These give insight into the average effective magnetic
fields present, interaction of the nuclear spin with the
adjacent atoms and the number of equivalent protons.
The NMR spectral assignments are given in Figs. 5–7.
In the solid state reflectance spectrum of HL, bands
2
observed at 34,730 and 28,730 cm are assigned to the
1
p
thiosemicarbazone moiety and the n ! p transitions of the
p
1
pyridyl ring, respectively [29], whereas the p ! p
The H NMR spectrum reveals four signals for the pyridyl
moiety, multiplet for the phenyl moiety and seven well
resolved peaks for the cyclohexyl moiety. The signals at
2
1
transitions are observed at 38,610 cm (Fig. 3). In the
spectra from DMF solution, these bands are shifted in
2
1
2
1
energy to 34,810, 29,410 and 39,010 cm having log 1
values 4.13, 3.32 and 4.20, respectively.
The IR spectrum of HL (Fig. 4) shows a broad band at
d ¼ 13:48 and 7.63 ppm are assigned to the NH and NH
protons, respectively. The intensity of these peaks decreases
on addition of D O, which suggests that they are easily
2
2
1
3
334 cm corresponding to the NH moiety linked to the
cyclohexyl group. The other bands observed in the spectrum
1
at 833 and 1582 cm are due to n(CyS) and n(CyN),
respectively, whereas the band at 1435 cm is due to the
cyclohexane ring [8,30]. A ring deformation band of
1
pyridine is observed at 607 cm . The absence of n(S–H)
exchangeable. These protons are shifted downfield because
they are attached to heteroatoms and so are easily subjected
to hydrogen bonding and are decoupled by the electrical
2
2
1
2
quadrupole effects. The proton attached to N appears as
singlet as expected since the NH protons are decoupled from
the nitrogen atoms and the protons from the adjacent atoms.
2
2
1
1
But contrary to this, NH shows coupling with the adjacent
band around 2700 cm suggests that HL remains in the
thione form in the solid state [31,32]. This thiosemicarba-
zone is found to act as a tridentate ligand in its copper(II)
complexes [33].
hydrogen H6 and hence give a doublet. This coupling is
clear in COSY, which can be attributed to the low NH
exchange rate. The peak at 8.80 ppm is assigned to be due to
the H10 proton. This proton is very sensitive to the electron
densities as it is close to the pyridyl nitrogen and is observed
to be deshielded due to the electronic effect of the phenyl
ring. The phenyl moiety appears as a multiplet at about
The one-dimensional and two-dimensional nuclear
magnetic resonance spectra are used in resolving the
1
carbon and hydrogen atoms. The H resonances were
assigned on the basis of the chemical shift values,
7.45 ppm where the chemical shift values are very close,
hence very difficult to be resolved. The complexity of the
COSY predicts that the spectrum is not strictly of the first
order. The peak (7.3 ppm) corresponding to the solvent
(CDCl ) appears to be superimposed with that of the phenyl
3
protons. The cyclohexyl moiety forms a chair conformation
and hence the hydrogens exist in two different electronic
environments, viz. axial and equatorial, and hence give
seven well-resolved peaks. The equatorial protons 2.08 ppm
(H5e) are found to resonate at a slightly higher frequency
compared to that of the axial protons 1.27 ppm (H5a). A
multiplet present at 4.32 ppm is attributed to the H6, which
is deshielded by the adjacent electronegative nitrogen.
1
1
Fig. 8 shows the H– H-correlation spectrum of
the compound. The COSY spectrum separates out
the interactions among the protons and establishes
the proton–proton couplings. The proton spectrum is
Fig. 3. Electronic spectrum of HL.

66
M. Joseph et al. / Journal of Molecular Structure 705 (2004) 63–70
1
Fig. 5. H NMR assignments of HL.
plotted along the X and Y-axes and can be seen as contours
in diagonal. In the proton NMR spectrum, we have already
identified a doublet at 8.80 ppm as of the pyridyl proton
H10. If we extend horizontal and vertical lines from this
point, it will eventually encounter off-diagonal cross peaks
at 7.36 ppm, which is assigned as peak due to the H11. That
is, the peak of the proton H10 is split by that of the proton at
H11. Similarly by extending the lines from the spot at
Similarly H5e and H4e protons split the peak of the axial
1
proton H5a. In the H NMR, the multiplet at 1.72 ppm is
already assigned to the H4e proton which interacts with five
other protons H5a, H5e, H4a, H3e and H3a where
interaction with H3a is very weak. All these couplings are
of vicinal type. The multiplet at 1.64 ppm is formed by the
coupling of H4a protons with the neighboring H4e, H3a and
H3e protons. The proton shows no coupling with the H5e
and H5a protons. The coupling between the H3a and H4a
protons give J values around 11 Hz, which is consistent with
diaxial type coupling constants. Even though, the coupling
in the region 1.5 ppm is intricate to resolve as the chemical
shift values of H3a, H3e and H5a are very close, it is clearly
evident from the spectrum that the H3a proton couples with
H4a and H3e. Similarly H3e is coupled with the H3a, H4e
and H4a protons. The same coupling is observed for the
protons at C1 and C2, which are magnetically equivalent to
the C5 and C4 protons. The H6 proton interacts with the
7
.36 ppm it will encounter off diagonal spots at 8.80 ppm
H10) and 7.70 ppm (H12). The multiplet at 7.36 ppm is
(
related to the number of possible orientations these
neighboring protons can adopt. The H12 proton is also
split by the H13 proton and vice versa. In the spectrum
around d 7.40 ppm, the contours are seen ambiguous and the
multiplet is assigned to the protons of the phenyl moiety.
The chemical shifts are very close, so this spectrum is not
strictly first order. The peak at 2.08 ppm is assigned to the
equatorial proton on the carbon atom C5. From the COSY, it
is shown to interact with three other protons H6, H5a and
H4e. The couplings are of diequatorial and axial/equatorial
type. The coupling constants agree well with those
corresponding to the chair conformation of cyclohexane.
1
NH and also with two protons of C1 and C5.
1
The C NMR spectrum was assigned on the basis of the
3
1
3
proton-decoupled C and the HMQC spectrum (Fig. 9).
The HMQC experiment provides the correlation between
13
Fig. 6. C NMR assignments of HL.

M. Joseph et al. / Journal of Molecular Structure 705 (2004) 63–70
67
1
Fig. 7. H– H COSY assignments of HL.
1
the protons and their attached heteronuclei through the
1
3.2. Crystal structure of HL
3
heteronuclear scalar coupling. The decoupled C spectrum
of the compound contains 15 peaks corresponding to the
The molecular structure of HL along with the atomic
numbering scheme is given in Fig. 10. The compound
crystallizes into a monoclinic lattice with space group P2 =n
1
3
fifteen magnetically unique atoms. The signal from C is
much weaker than that of the corresponding proton NMR.
From the HMQC spectrum, it is evident that the peaks at
1
and the molecule shows an Z configuration with respect to
the C8yN3 bond. A torsion angle value of 2174.318
corresponding to the S1–C7–N2–N3 moiety confirms the
trans configuration of the thiocarbonyl S1 atom with
respect to the hydrazine nitrogen atom N3 [35]. Similarly,
1
77.02, 152.52 and 148.72 ppm are of the non-protonated
carbons and they correspond to the S ¼ C7, N ¼ C8 and C9
carbon atoms, respectively. The carbon atom closest to the
electronegative atom is farthest downfield. The carbon
atoms on the pyridyl ring can be assigned as C10, 142.38;
C11, 137.81; C12, 124.11; C13, 126.05. Aromatic carbons
of the phenyl ring appear around 129 ppm and it is very
difficult to be resolved. The peaks at 32.74, 24.89, 25.61 and
˚
the N2–N3 bond length (1.367 A) is closer to single bond
˚
˚
length (1.45 A) than to double bond length (1.25 A) [36].
˚
The C7–S1 bond distance (1.675 A) is close to that
˚
expected of a CyS double bond (1.60 A) [36] and the
5
2.85 ppm are assigned to C1, C2, C3 and C6 carbons,
˚
C8–N3 bond length (1.290 A) is nearly the same as that of
respectively. The C4 and C5 are chemically equivalent with
C2 and C1 carbons and hence have the values 24.89 and
˚
the CyN double bond (1.28 A) [37]. These bond distances
are in strong support of the existence of 2-benzoylpyridine
N(4)-cyclohexylthiosemicarbazone in the thione form in
3
2.74 ppm, respectively.
1
Fig. 8. H– H COSY spectrum of HL.
1
13
Fig. 9. C– H HMQC spectrum of HL.
1

68
M. Joseph et al. / Journal of Molecular Structure 705 (2004) 63–70
Fig. 10. ORTEP diagram for HL, displacement ellipsoids are drawn at 50% probability level and hydrogen atoms are shown as small spheres of arbitrary radii.
the solid state. A collection of the data observed in our study
on the various bond distances in the crystal structures of
thiosemicarbazones is presented in Table 3. The mean plane
deviation calculations show that the pyridyl ring Cg(1) is
˚
planar with a max deviation of 20.0096 A. The thiosemi-
carbazone moiety also is planar with a maximum mean
evident from the figure that the unit cell as a whole is packed
in a centrosymmetric manner especially at the center, where
two units each comprising of two molecules are symme-
trically packed in a ‘face-to-face’ manner. The self-
assembly of the molecules in the crystal lattice in this
manner is effected by the p–p interaction between the two
pyridyl rings, i.e. the Cg(1) of the two neighboring units are
˚
plane deviation value of 20.0596 A and a torsion angle
˚
observed at a distance of 3.8582 A whereas these are
˚
observed at an average distance 5.7295 A between the Cg(1)
value of 3.658 for N2–N3–C8–C9 confirms that the
C8–C9 bond is in the same plane of the thiosemicarbazone
moiety. Also, the atoms C9, N4, C10, C11, C12, C13 and C8
are coplanar as evidenced from the maximum deviation
of one unit with the phenyl ring Cg(3) of the adjacent
molecule (Table 4). The C–H–p interaction, viz.
C3–H3B–Cg(3), also contributes to the stability of the
crystal lattice, where Cg(3) is the cyclohexyl ring of the
adjoining molecular unit.
˚
value of 20.0205 A from the plane. The dihedral angle
formed by the two least square planes Cg(3) and Cg(1) is
equal to 678, which confirms the non-coplanarity of the two
rings. The intramolecular hydrogen bonding interaction
N(1)–H(1)N(1)–N(3) leads to the formation of a five
membered ring comprising of N(1), H(1)N(1), C(7), N(2)
and N(3). A similar six membered ring involving N(2),
H(1)N(2), N(3), C(8), C(9) and N(4) is also developed by
the N(2)–H(1)N(2)–N(4) intramolecular hydrogen bonding
interaction in the compound. The axial substitution of the
cyclohexyl ring at the N1 nitrogen of the thiosemicarbazone
is confirmed by a torsion Cg(3) ¼ C(14), C(15), C(16),
C(17), C(18), C(19) value of 2178.268 for the N2–C7–
N1–C6 bond. Ring puckering analysis and least square
planes calculations show that the cyclohexyl ring, Cg(2)
Table 3
A comparison of the selected bond lengths ( A˚ ) observed in various
thiosemicarbazones
˚
Compound Bond distances (A)
N1–C7
C7–S1
C7–N2
N2–N3
N3–C8
HL
1.328(19) 1.675(15) 1.364(18) 1.367(17) 1.290(18)
BpytTsc
ApytTsc
DpktTsc
DpkpTsc
1.343(4)
1.347(6)
1.349(5)
1.339(3)
1.681(3)
1.692(4)
1.671(4)
1.676(2)
1.360(4)
1.349(6)
1.386(4)
1.362(2)
1.366(3)
1.364(5)
1.371(4)
1.357(2)
1.362(2)
1.295(4)
1.293(6)
1.308(4)
1.286(2)
1.295(2)
˚
DpkmpTsc 1.349(2)
MbTsc
1.6686(18) 1.377(2)
adopts a chair conformation (Q ¼ 0:5701 A). The atoms
T
1.3238(18) 1.6987(15) 1.3398(18) 1.3886(17) 1.271(2)
C1, C2, C4 and C5 constitute the best fitting plane of the
cyclohexyl ring, and the atoms C3 and C6 deviate by 1.2462
BpytTsc, 2-benzoylpyridine 3-tetramethyleneiminyl thiosemicarbazone
[19]; ApytTsc, 2-acetylpyridine 3-tetramethyleneiminyl thiosemicarbazone
˚
and 21.2358 A, respectively, on either side of this plane.
[
20]; DpktTsc, Di-2-pyridyl ketone 3-tetramethyleneiminyl thiosemicarba-
zone [21]; DpkpTsc, di-2-pyridyl ketone N(4)-phenyl thiosemicarbazone
22]; DpkmpTsc, di-2-pyridyl ketone N(4)-methyl N(4)-phenyl thiosemi-
carbazone [23]; MbTsc, p-methoxybenzaldehyde thiosemicarbazone [24].
The packing of the molecule in a unit cell is shown in
Fig. 11. The unit cell is viewed down the ‘a’-axis and four
molecules of the compound are arranged in the unit cell. It is
[

M. Joseph et al. / Journal of Molecular Structure 705 (2004) 63–70
69
Fig. 11. Unit cell packing diagram of HL, viewed down the ‘a’-axis.
Table 4
H bonding, p–p and CH–p interactions of HL
˚
˚
H bonding (A, A)
D–H–A
D–H
0.87
0.90
H–A
2.15
2.01
D–A
D–H–A
N1–H1N1–N3
N2–H1N2–N4
2.5905
2.6853
117
131
p–p interactions
Cg(I)–Res(I)–Cg(J)
˚
˚
a (A)
0.00
˚
Cg–Cg (A)
3.8582
b (A)
13.64
53.66
48.82
a
Cg(1) [1]–Cg(1)
b
Cg(1) [1]–Cg(3)
5.4642
67.00
c
Cg(3) [1]–Cg(1)
5.9949
69.28
Cg(1) ¼ N(4),C(9), C(10), C(11),C(12),C(13)
Cg(2) ¼ C(1)0, C(2), C(3), C(4), C(5), C(6)
Cg(3) ¼ C(14), C(15), C(16), C(17), C(18), C(19)
CH–p interactions
X–H(I)–Cg(J)
˚
˚
H–Cg (A)
2.8680
X–H–Cg (8)
139.71
X–Cg (A)
3.6608
d
C(3)–H(3B)–Cg(3)
D, Donor; A, acceptor, Cg, centroid; a; dihedral angles between planes I and J; b; angle Cg(1)–Cg(J); equivalent position codes: a ¼ 2x; 1 2 y; 2z;
b ¼ 21 þ x; y; z; c ¼ 1=2; 1=2 2 y; 1=2 þ z; d ¼ 2x; 1 2 y; 1 2 z:

7
0
M. Joseph et al. / Journal of Molecular Structure 705 (2004) 63–70
[12] D.X. West, I.S. Billeh, J.P. Jesinski, J.M. Jesinski, R.J. Butcher,
4
. Supplementary data
Transition Met. Chem. 23 (1998) 209.
[
[
[
[
[
[
13] D.X. West, N.M. Kozub, G.A. Bain, Transition Met. Chem. 21 (1996)
Crystallographic data for structural analysis has been
5
2.
deposited with the Cambridge Crystallographic Data center,
CCDC for compound HL. Copies of this information maybe
obtained free of charge from the Director, CCDC, 12 Union
Road, Cambridge, CB2, IEZ, UK (Fax: þ44-1223-336-033;
e-mail: deposit@ccdc.cam.ac.uk or http://www.ccdc.cam.
ac.uk).
14] M.R.P. Kurup, M. Joseph, Synth. React. Inorg. Met. -Org. Chem. 33
(2003) 1275.
15] R.P. John, A. Sreekanth, M.R.P. Kurup, S.M. Mobin, Polyhedron 21
(
2002) 2515.
16] R.P. John, A. Sreekanth, M.R.P. Kurup, A. Usman, I.A. Razak, H.K.
Fun, Spectrochim. Acta 59A (2003) 1349.
17] A. Sreekanth, S. Sivakumar, M.R.P. Kurup, J. Mol. Struct. 655 (2003)
4
7.
18] V. Philip, V. Suni, M.R.P. Kurup, M. Nethaji, Polyhedron 23 (2004)
225.
1
Acknowledgements
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[
19] A. Sreekanth, M.R.P. Kurup, Polyhedron 23 (2004) 969.
20] A. Sreekanth, M.R.P. Kurup, H.-K. Fun, submitted.
The authors are thankful to Regional Sophisticated
Instrumentation Center, CDRI, Lucknow, India, for the
elemental analysis and Sophisticated Instruments Facility,
IISc Bangalore, India for NMR measurements. M.R.P.
Kurup is thankful to the State Committee on Science,
Technology and Environment, Thiruvananthapuram, India
for financial support.
21] A. Usman, I.A. Razak, S. Chantrapromma, H.K. Fun, V. Philip, A.
Sreekanth, M.R.P. Kurup, Acta Crystallogr. C 58 (2002) o652.
22] V. Suni, M.R.P. Kurup, M. Nethaji, unpublished data.
23] V. Philip, M.R.P. Kurup, M. Nethaji, submitted for publication.
24] V. Suni, S. Preetha, M.R.P. Kurup, M. Nethaji, submitted.
25] G.M. Sheldrick, SHELXTL Version 5.1, Software Reference Manual,
Bruker AXS Inc, Madison, Wisconsin, USA, 1997.
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Software, Siemens Analytical X-ray Instruments Inc., Madison,
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27] A.L. Speck, PLATON, a Multipurpose Crystallographic Tool, Utrechi
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