X-ray crystallographic and 2D HETCOR NMR studies of 2-acetylthiophene-o-aminobenzoylhydrazone: synthesis and spectral studies of its transition metal complexes

Article abstract of DOI:10.1016/j.molstruc.2005.11.012

The coordination chemistry of the ligand 2-acetylthiophene-o-aminobenzoylhydrazone (ATABZ) with oxovanadium(IV), manganese(II), cobalt(II), nickel(II), copper(II), zinc(II) and cadmium(II) has been studied wherein the complexes were characterized by elemental analyses, magnetic moments, conductivity measurements, spectral (IR, 1D and 2D HETCOR NMR, EPR and UV-VIS) and thermal studies. The ligand ATABZ crystallizes in the orthorhombic system, space group Pca21 with lattice parameters a=8.5279(17) ?, b=5.8101(11) ?, c=25.720(5) ?, V=1274.3(4) ?³ and Z=4. All the complexes are neutral in nature and possess four-coordinate geometry around the metal ion except oxovanadium(IV) complex, which is five-coordinate. The X-band EPR spectra of the copper(II) and oxovanadium(IV) complexes at both room temperature and liquid nitrogen temperature have been recorded and their salient features are reported. The antibacterial and antifungal activities of the ligand and complexes have been carried out.

Full text of DOI:10.1016/j.molstruc.2005.11.012

Journal of Molecular Structure 788 (2006) 22–29
www.elsevier.com/locate/molstruc
X-ray crystallographic and 2D HETCOR NMR studies
of 2-acetylthiophene-o-aminobenzoylhydrazone: synthesis
and spectral studies of its transition metal complexes
a
a
Kalagouda B. Gudasi a, , Rashmi V. Shenoy , Ramesh S. Vadavi ,
*
Siddappa A. Patil a, Munirathinam Nethaji b
a Department of Chemistry, Karnatak University, Dharwad -580 003, Karnataka, India
b Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore-560 012, India
Received 12 August 2005; received in revised form 7 November 2005; accepted 10 November 2005
Available online 14 February 2006
Abstract
The coordination chemistry of the ligand 2-acetylthiophene-o-aminobenzoylhydrazone (ATABZ) with oxovanadium(IV), manganese(II),
cobalt(II), nickel(II), copper(II), zinc(II) and cadmium(II) has been studied wherein the complexes were characterized by elemental analyses,
magnetic moments, conductivity measurements, spectral (IR, 1D and 2D HETCOR NMR, EPR and UV-VIS) and thermal studies. The ligand
˚
˚
˚
ATABZ crystallizes in the orthorhombic system, space group Pca21 with lattice parameters aZ8.5279(17) A, bZ5.8101(11) A, cZ25.720(5) A,
3
˚
VZ1274.3(4) A and ZZ4. All the complexes are neutral in nature and possess four-coordinate geometry around the metal ion except
oxovanadium(IV) complex, which is five-coordinate. The X-band EPR spectra of the copper(II) and oxovanadium(IV) complexes at both room
temperature and liquid nitrogen temperature have been recorded and their salient features are reported. The antibacterial and antifungal activities
of the ligand and complexes have been carried out.
q 2006 Elsevier B.V. All rights reserved.
Keywords: 2-Acetylthiophene; Hydrazone ligand; Transition metal complexes; X-ray structure determination
1. Introduction
Especially, the 2-substituted thiophenes are an important
constituent of the drugs methapyrilene, temidap, tienilic acid
and temocillin [6]. The metal complexes of thiosemicarba-
zones containing the thiophene moiety have exhibited
enhanced antiamoebic activity [7].
Hydrazones are a versatile class of ligands having great
physiological and biological activities, and have found use as
insecticides, anticoagulants, antitumour agents, antioxidants
and plant growth regulators [1]. Their metal complexes have
found applications in various chemical processes like
nonlinear optics, sensors, medicine, etc. [2]. Furthermore,
hydrazones incorporating heterocyclic moieties are well
known for their metal binding ability and exhibit interesting
coordinating behavior with transition metal ions [3,4], which
makes them interesting from the structural point of view
also.
Knowledge of the structural peculiarities of a biologically
active molecule and its inherent 3 -dimensional structure is a
necessary condition for investigating the interaction with
metal ions and for designing new compounds. To gain an
insight into the conformational aspects of the title ligand and
in order to study its coordination behavior towards transition
metal ions, we have designed and synthesized a compound
by condensing two biologically active moieties, o-amino-
benzoylhydrazide [8] with 2-acetylthiophene.
Of the heterocyclic moieties the thiophene ring system is
ubiquitous in nature and is known to exhibit antifungal,
bacteriostatic, analgesic and anti-inflammatory activities [5].
The single crystal structures of a few hydrazones derived
from o-aminobenzoylhydrazide have been reported [9–11]. In
the present work, we report for the first time, the X-ray
crystal structure of 2-acetylthiophene-o-aminobenzoylhydra-
zone (ATABZ) and the synthesis, characterization and
biological evaluation of its oxovanadium(IV), manganese(II),
cobalt(II), copper(II), nickel(II), zinc(II) and cadmium(II)
complexes.
*
Corresponding author. Tel.: C91 836 2460129/215286; fax: C91 836
2771275.
E-mail address: kbgudasi@rediffmail.com (K.B. Gudasi).
0022-2860/$ - see front matter q 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.molstruc.2005.11.012

K.B. Gudasi et al. / Journal of Molecular Structure 788 (2006) 22–29
23
2. Experimental
2.1. Materials and general methods
All chemicals were of A.R. grade and were used without
further purification. Methyl anthranilate (S.D. Fine-chem),
hydrazine hydrate (Rankem) and 2-acetylthiophene (Sisco-
Chem) were used as obtained. o-Aminobenzoylhydrazide was
prepared by an earlier method [12].
Elemental analyses of the ligand and complexes were
performed on a thermoquest CHN analyzer. The complexes
were analyzed for their metal content by EDTA titration after
decomposition with a mixture of HCl and HClO4. The
chloride content was determined as AgCl after decomposition
with HNO3. The sulphate content in the VO(IV) complex was
determined as barium sulphate, gravimetrically. The IR
spectra were recorded as KBr pellets in the 4000–400 cmK1
region on a Nicolet 170 SX FT-IR spectrometer. Electronic
absorption spectra were measured in DMSO with a Cary-Bio
50 Varian spectrophotometer. The 1D and 2D NMR spectra of
the ligand were recorded in dmso-d6 on a Bruker AMX 500
1
spectrometer operating at 500.13 MHz for H and 127.77 for
1
1
13C using a 5 mm H/13C dual probe. The H and 13C NMR
spectra of the cadmium(II) complex were recorded on a
Bruker Avance 300 spectrometer operating at 300.13 MHz for
1H and 75.47 MHz for 13C using a 5 mm1H/13C dual probe.
Magnetic susceptibility measurements were made at room
temperature on a Faraday balance using Hg[Co(CNS)4] as the
calibrant and the diamagnetic corrections were made by direct
weighing of the ligand for diamagnetic pull. Conductance
measurements were recorded in DMSO (10K3 M) using an
ELICO-CM-82 conductivity bridge with platinum electrodes
and cell constant 0.53. Thermogravimetric analyses of the
complexes were carried out under N2 atmosphere in the 25–
1000 8C range at a heating rate of 10 8C/min using a TGA
Analyzer, Perkin Elmer, US. EPR spectra of the copper(II)
and oxovanadium(IV) complexes were recorded with a Varian
E4 X-band spectrometer at both RT and LNT using TCNE as
‘g’ marker.
2.2. Syntheses
2.2.1. 2-Acetylthiophene-o-aminobenzoylhydrazone (ATABZ)
(Scheme 1)
2-Acetylthiophene (10.8 g, 100 mmol) was added to a
methanolic (130 cm3) solution of o-aminobenzoylhydrazone
(15.1 g, 100 mmol) and the mixture was stirred for 2–3 h to
yield a yellow crystalline product. Completion of the reaction
was checked by TLC on precoated silica gel plates. The
isolated compound was filtered as yellow crystals, washed with
cold ethanol and dried in air. Recrystallization from hot
methanol yielded the light yellow crystals of ATABZ. m.p.
198–200 8C, yield: 87%.
2.2.2. Preparation of complexes
To a clear hot solution of ATABZ (0.259 g, 1 mmol) in
25 cm3 methanol was added 1 mmol of metal chloride/sulphate

24
K.B. Gudasi et al. / Journal of Molecular Structure 788 (2006) 22–29
Table 2
and stirred for 3–4 h. The solution was then concentrated to a
small volume and the precipitate obtained was filtered, washed
with cold ethanol and air-dried. Attempts to grow single
crystals of the complexes were unsuccessful. Yield: 69–74%.
Crystal data and structure refinement of ATABZ
Empirical formula
Formula weight
Temperature, K
Crystal system
C13H13N3OS
259.32
293
Orthorhombic
Pca21
2.3. X-ray crystallography
Space group
˚
Unit cell dimensions
aZ8.5279(17) A aZbZgZ908
˚
The crystal structure of the title compound was determined
by single crystal X-ray diffraction with dimensions of 0.62!
0.51!0.33 mm3. The data were collected on a BRUKER
SMART APEX CCD Diffractometer at 293 K, using graphite-
bZ5.8101(11) A
˚
cZ25.720(5) A
1274.3(4)
3
˚
V, A
Z
4
Density (calculated)(mg/m3)
1.3516
˚
monochromatized MoKa radiation (lZ0.71073 A) and scan
Habit
Absorption coefficient (mmK1
˚
l, A
Rectangular
mode in the range 3.17–28.02. The structure was solved by
direct methods and refined by Full-matrix least squares on F2.
All of the non-hydrogen atoms were refined with anisotropic
temperature factors. The calculations were performed using the
SHELXTL programme [13]. Crystallographic data of ATABZ
have been deposited at the Cambridge Crystallographic Data
Centre (CCDC), 12 Union Road, Cambridge CBZ 1EZ, UK.
Copies of the data can be obtained free of charge by quoting the
deposition number 269110.
)
0.245
0.71073
F(000)
544
Range (8) for data collection
No. of reflections measured
No. of unique reflections
R(Int)
3.17–28.02
9374
2974
0.0332
No. of observed reflections
Refinement method
Final R indices (IO2s (I))
Goodness-of-Fit-on F2
Final R indices (all data)
2342
Full matrix least squares on F2
0.0617
1.115
0.0825
3. Results and discussion
The elemental analyses, magnetic moments and conduc-
tivity data are presented in Table 1. All the metal complexes
possess 1:1 (M: L) stoichiometry. The complexes are soluble in
EtOH, MeOH, CHCl3, DMF and DMSO but are insoluble in
CCl4, C6H6 and H2O. The molar conductance values of the
complexes ranging from 0.41–0.56 OhmK1 cm2 molK1 reveal
their non-electrolytic nature [14].
C5.64 and C17.958, respectively. The torsional angle of
K177.468 exhibited by S(1)-C(4)-C(5)-C(13) indicate the
C(13) of the methyl group to be in a trans position to
the sulphur of the thiophene moiety. The torsional angles
˚
S(1)-C(4)-C(5)-N(1) [C2.24 A] and N(1)-N(2)-C(6)-O(1)
˚
[K5.11 A] indicate that S(1), N(1) and O(1) are cis to
each other. The molecular packing diagram (Fig. 2) shows
3.1. Description and discussion of the crystal structure of
ATABZ
Table 3
˚
Selected bond lengths (A) and angles (8) for ATABZ
The crystal data, structure refinement and selected bond
lengths and bond angles of ATABZ are given in Tables 2
and 3, respectively. The ORTEP [15] and molecular packing
diagrams are depicted in Figs. 1 and 2 respectively. The
analysis of the crystal structure of ATABZ evidences that it
is coplanar. The average C–C bond lengths and bond angles
Atom
Bond lengths
Atom
Bond lengths
S(1)-C1
1.697(4)
1.712(3)
1.234(3)
1.384(4)
1.276(4)
1.355(4)
1.350(5)
1.318(7)
1.411(6)
1.365(5)
Bond angles
92.2(2)
C(4)-C(5)
C(5)-C(13)
C(6)-C(7)
C(7)-C(8)
C(7)-C(12)
C(8)-C(9)
C(9)-C(10)
C(10)-C(11)
C(11)-C(12)
1.466(4)
1.485(5)
1.486(4)
1.418(4)
1.388(4)
1.411(5)
1.367(5)
1.385(5)
1.362(5)
S(1)-C4
O(1)-C(6)
N(1)-N(2)
N(1)-C(5)
˚
of the phenyl ring (Fig. 1) lie between 1.316–1.418 A and
N(2)-C(6)
117–123.098, respectively, which is similar to the analogous
compound di-2-pyridylketone-2-aminobenzoylhydrazone
˚
[16]. All the C–C bond lengths [1.364 A] and C–C–C
angles [112.568] of the thiophene ring as well as the C–S
˚
bond lengths [1.70 A] and C–S–C angle [92.168] are in
accordance with that of a typical thiophene moiety [17].
˚
The CaO [C(6)-O(1)] displays a bond distance of 1.234 A
which is consistent with a carbonyl double bond [18]. The
C(7)-C(6)-N(2) angle is 118.78 as for an sp2 hybridized
carbon[(6)]. The ligand lies in two planes with plane I
[C(7), C(8), C(9), C(10), C(11), C(12)] making a dihedral
angle of 175.558 with plane II [S(1), C(1), C(2),C(3), C(4)].
The conformational designations across C(6)-C(7)-C(8)-N(3)
and O(1)-C(6)-C(7)-C(8) indicate the Csynperiplanar
arrangement and the corresponding torsional angles are
N(3)-C(8)
C(1)-C(2)
C(2)-C(3)
C(3)-C(4)
Atom
Atom
Bond angles
119.1(3)
122.1(3)
118.6(3)
123.2(3)
119.2(3)
117.5(3)
121.5(3)
120.7(3)
120.7(3)
118.6(4)
123.1(3)
C(1)-S(1)-C(4)
C(5)-N(1)-N(2)
C(6)-N(2)-N(1)
C(2)-C(1)-S(1)
C(1)-C(2)-C(3)
C(3)-C(4)-S(1)
C(5)-C(4)-S(1)
C(3)-C(4)-C(5)
C(4)-C(5)-C(13)
O(1)-C(6)-N(2)
O(1)-C(6)-C(7)
N(2)-C(6)-C(7)
C(8)-C(7)-C(6)
C(12)-C(7)-C(6)
C(12)-C(7)-C(8)
N(3)-C(8)-C(7)
N(3)-C(8)-C(9)
C(9)-C(8)-C(7)
C(10)-C(9)-C(8)
C(9)-C(10)-C(11)
C(9)-C(10)-C(11)
C(12)-C(11)-C(10)
C(11)-C(12)-C(7)
119.0(3)
116.8(3)
111.9(4)
113.6(4)
110.1(3)
119.5(2)
130.4(3)
119.0(3)
120.0(3)
121.2(3)
118.7(3)

K.B. Gudasi et al. / Journal of Molecular Structure 788 (2006) 22–29
25
The EPR spectrum of the polycrystalline oxovanadium(IV)
complex (Fig. 4) at room temperature exhibits an eight-line
pattern corresponding to the well resolved parallel and
perpendicular components of g-and hyperfine (hf) A -tensors.
The various spin-Hamiltonian parameters have been calculated
and are as follows: gkZ2.01, gtZ2.02, g0Z2.01, AkZ
K85.71, AtZ10 and A0 (isotropic hf parameter) ZK21.90.
The trend ge!gk!gt shows the presence of the
unpaired electron in the dxy orbital. Using the values of E1
(16,620 cmK1) and E2 (11,100 cmK1) obtained from elec-
tronic absorption spectra and the above g parameters, the spin-
orbit coupling constant (l) has been calculated using the
relations,
Fig. 1. ORTEP diagram of ATABZ.
the presence of one intra molecular and two intermolecular
hydrogen bondings. One of the hydrogens [H3A] of N(3) of
NH2 group is involved in intra molecular hydrogen
bonding with the O(1) of the CaO entity. The O(1) of
the carbonyl group also acts as an acceptor to H(12) of the
phenyl ring and H(2A) of the NH group of another
molecule. The N(2A)-H(2A)/O(1)[I] ([I] ZxK1/2, Ky,
8l
2l
gjj Z geK
and gt Z geK
E1
E2
According to Kivelson and Lee [21], a theoretical value of
170 cmK1 is predicted for l for C4V symmetry. In the present
case, the l value obtained is 55 cmK1, the reduction in its value
for the double bonded oxovanadium (VaO)2C complex being
attributed to the substantial p bonding.
˚
Cz) distance (2.943 A) is shorter than the C(12)-H(12)/
˚
O(1)[I] distance of 3.225 A whereas the N(3)-H(3A)/
˚
O(1)[0] ([0]Zx, y, z) distance is 2.655 A. Interestingly these
3.3. UV spectra
hydrogen bonds link the molecules in a helical-like structure
as shown in Fig. 3.
The Uv-visible spectra of ligand and complexes were taken
in order to assign the geometries around the metal ions. The
electronic spectrum of the ligand APABZ showed two strong
bands at 30,769 and 28,169 cmK1 assignable to the nKp*
transitions.
3.2. EPR spectra
The EPR spectra of the polycrystalline sample of
[Cu(ATABZ)Cl2] showed identical features at both room
temperature (RT) and liquid nitrogen temperature (LNT) with
two gk and one gt values. The g values obtained are gk Z
2.16, gk2Z2.24 and gtZ2.10 (at RT) and gk1Z2.15, gk12Z
2.23 and gtZ2.09 (at LNT). The gkOgtO ge (2.00277)
indicates the localization of the unpaired electron in the dx2Ky2
orbital.
The electronic spectrum of the manganese(II) complex
shows three bands at 25,706, 27,397 and 29,154 cmK1 which
6
6
6
are assigned to the A1/4E, A1/4T2(D) and A1/4E(D)
transitions, respectively as for a tetrahedrally coordinated
manganese(II) ion. The magnetic moment value of 5.73 BM
obtained supports this assignment.
The electronic spectrum of the nickel(II) complex shows a
3
single band at 14,598 cmK1 assigned to the T1(E)/3T1(P)
The gk value is less than 2.3 indicating the covalent nature
of the metal-ligand bonding [19]. The axial factor G is 2.5 (RT)
and 2.4 (LNT), which is less than 4 indicates considerable
metal–metal interaction in the complex [20]. This is also
supported by its magnetic moment value, which is slightly
decreased.
transition which is consistent with a tetrahedral geometry. The
broad band at 25,641 cmK1 tailing into the visible region is
assigned to the charge-transfer band [3].
In the electronic spectrum of cobalt(II) complex, two bands
observed at 15,243 and 25,585 cmK1 are due to
Fig. 2. Molecular packing diagram of ATABZ showing the intra-and intermolecular hydrogen bondings.

26
K.B. Gudasi et al. / Journal of Molecular Structure 788 (2006) 22–29
In the electronic spectrum of oxovanadium(IV) complex,
the two spin allowed transitions observed at 11,100 and
16,638 cmK1 were due to the 2B2/E and 2B2/2B1,
respectively as expected for a C4V symmetry. The third band
2
due to B2/2A1 transition was masked by the strong charge
transfer transition and hence was not observed [22,23]. A
magnetic moment value of 1.72 BM was obtained as expected
for an SZ1/2 system.
3.4. IR spectra
In order to ascertain the mode of bonding of ATABZ to the
metal ions, the IR spectra of the free ligand was compared with
those of its metal complexes. The diagnostic IR bands are
given in Table 4.
The IR spectrum of ATABZ exhibits two sharp bands of
medium intensity at 3469 and 3353 cmK1 which are assigned
to the nasym and nsym stretching frequencies of the free NH2
group, respectively [24]. A broad band at 3200 cmK1 is due to
NH stretching frequency of the amide moiety. Three strong
vibrations at 1629, 1537 and 1255 cmK1 are ascribed to the
amide I (nCaO), amide II and amide III bands respectively
[25]. The appearance of the nCaO band at a relatively lower
wave number is due to the presence of strong intra molecular
hydrogen bonding between free NH2 and carbonyl oxygen,
which is supported by single crystal X-ray study. A weak band
at 1606 cmK1 is due to the nCaN of the azomethine group
whereas the band at 1015 cmK1 is assigned to the nN–N [3].
The medium intensity band at 1355 cmK1 is ascribed to the
ring stretching vibration of the nCSC of the thiophene moiety
[26].
Fig. 3. Helical-like structure of ATABZ shown in space filling mode.
In the IR spectra of all the complexes, the bands due to
the nsym and nasym modes of the free NH2 group are shifted
to higher frequency by 39–71 and 12–67 cmK1, respectively
indicating the breakdown of hydrogen bonding between
NH2 and OCaO group. The amide I(nCaO) undergoes a
negative shift by 14–22 cmK1 in all the complexes followed
by the upward shift of the amide II and III bands by 13–15
and 5–8 cmK1, respectively. These changes indicate the
involvement of carbonyl oxygen in coordination to the
metal [25]. The azomethine frequency is shifted to lower
wave number in all the complexes indicating ligation of
azomethine nitrogen to metal which is further supported by
an increase in the nN–N band by 13–22 cmK1 [22]. The
nCSC vibration remains almost unperturbed in all the
complexes indicating the non-participation of the sulphur
atom in coordination [26].
4A2(F)/4T1(P) transitions. A weak band at 16,583 cmK1 is
due to spin–spin coupling. These assignments are supported by
the meff value of 4.46 BM which is consistent with tetrahedral
configuration around the cobalt(II) ion.
The broad band between 14,285–13,157 cmK1 in the
electronic spectrum of the copper(II) complex is formed by
the combination of the 2B1g/2A1g and 2B1g/2Eg transition as
for a square planar configuration around the Cu(II) ion. A broad
band centered at 28,571 and 27,397 cmK1 in the zinc(II) and
cadmium(II) complexes, respectively was assigned to the
charge-transfer transitions [3].
3.5. NMR spectra
In order to study the hydrogen bonding interactions in the
solution state, and to assign the respective protons and carbons,
the 2D HETCORR NMR study of ATABZ was carried out.
The 1H NMR spectra of ATABZ and its cadmium(II) complex
were recorded in dmso-d6. The spectral assignments were
made based on comparisons with NMR assignments of methyl
anthranilate [27], 2-acetylthiophene [28] and 2D HETCORR
Fig. 4. EPR spectrum of [VO(ATABZ) SO4 H2O] at LNT.

K.B. Gudasi et al. / Journal of Molecular Structure 788 (2006) 22–29
27
Table 4
IR spectral assignments of ATABZ and its transition metal complexes
Compound
n(NH2)
n(CaO)amide
n(CaN)
n(NH) amide Amide II
Amide III
n(N-N)
n(CSC)
nasym
nsym
ATABZ
3469sh
3505sh
3515 sh
3478 sh
3463 sh
3480 sh
3485 sh
3540sh
3353sh
3402sh
3383sh
3365sh
3372sh
3375sh
3376sh
3420sh
1629s
1612s
1606s
1618s
1615s
1616s
1615s
1615s
1606m
1587m
1592m
1598m
1597m
1596m
1593m
1592m
3200m
3258m
3274m
3275m
3273m
3273m
3277m
3278m
1537s
1255s
1015m
1028m
1037m
1035m
1034m
1035m
1030m
1029m
1355m
1357m
1356m
1358m
1355m
1353m
1354m
1355m
(Cd(ATABZ)Cl2)
(Co(ATABZ)Cl2)
(Cu(ATABZ)Cl2)
(Ni(ATABZ)Cl2))
(Mn(ATABZ)Cl2)
(Zn(ATABZ)Cl2)
((VO(ATABZ)SO4
H2O)
1550m
1552m
1552m
1553m
1553m
1550m
1552m
1260m
1255m
1252m
1252m
1255m
1263m
1263m
sh, sharp; s, strong; m, medium.
NMR of ATABZ. The 1H and 13C NMR data for ATABZ and
its cadmium(II) complex is given in Table 5. The numbering
scheme for the assignments of carbons and protons is given in
Scheme 1. and the 2D HETCORR of ATABZ is displayed in
Fig. 5.
due to the loss of two coordinated chlorides. Further weight
loss of 66.6% (Calcd 66.65%) between 360–580 8C is assigned
to the loss of a ligand molecule. Finally the most stable oxide
NiO is formed. The metal percentage of 15.0% is in agreement
with the values obtained by metal determinations (Calcd
15.1%).
The NH proton resonates as a singlet in the downfield region
(10.51 ppm). The resonance due to the methyl protons was
observed as a singlet at 3.34 ppm while that of NH2 also
appeared as a singlet at 6.22 ppm. The aromatic protons of the
phenyl ring are observed as doublets at 7.60 [H10] and 6.76
[H13] and as triplets at 7.20 [H12] and 6.58 ppm [H11]. The
signals at 7.50, 7.10 and 7.54 ppm were observed as a doublet,
triplet and doublet, respectively and are assigned to H2, H3 and
H4 of the thiophene moiety
In the case of the zinc(II) complex a weight loss of 83.3%
(Calcd 83.4%) in the 200–600 8C region is due to the loss of
two coordinated chlorides and a ligand molecule. The plateau
obtained on heating above 600 8C with a residual weight of
20.5% (Calcd 20.5%) accounts for the formation of stable ZnO
and tallies with the metal analysis (16.5%).
1
3.7. Biological activity
In the H NMR spectrum of the cadmium(II) complex, the
NH singlet undergoes an upfield shift to 9.56 ppm probably due
to the breakdown of intra molecular hydrogen bonding
between carbonyl oxygen and amide NH upon complexation.
The H10, H4 and H2 signals are merged together and shifted
upfield to give a multiplet at 7.42 ppm. A triplet at 7.15 ppm is
due to the merger of the H12 and H3. The H13 and H11 signals
undergo a slight up field shift of 0.06 and 0.09 ppm
respectively whereas the methyl singlet remains almost
unperturbed.
The 13C NMR spectrum of ATABZ showed a signal at
166.21 ppm assigned to the carbonyl carbon (C8) whereas a
peak at 3.34 ppm is due to the methyl carbon (C7). The signals
due to the quaternary carbons C5, C6, C8, C9 and C14 were
observed at 132.49, 150.07, 166.21, 115.0 and 143.94 ppm. In
the 13C NMR spectrum of the cadmium(II) complex the C8 and
C6 signals are shifted downfield to 167.52 and 150.86 ppm
indicating the involvement of carbonyl oxygen and azomethine
nitrogen in ligation, respectively. All the other signals remain
almost unperturbed.
The antibacterial and antifungal activities of the ATABZ
and its transition metal (II) complexes were evaluated against
the bacteria Pseudomonas aeuregenosa (PA) (Gram negative)
Table 5
1H and 13C NMR data of ATABZ and its cadmium(II) complex
Position
ATABZ
13C
Cd(II) complex*
1H
13C
1H
NH
C2
–
10.51 (s)
7.50 (d, JZ3.4)a
–
9.56 (s)
128.43
128.00
129.28
132.49
150.07
15.21
166.21
115.0
129.51
115.23
132.49
116.91
143.94
–
128.44
128.02
129.52
132.59
150.86
15.20
167.52
115.0
129.27
115.22
132.50
116.69
143.98
–
–
C3
7.10 (t, JZ4.5)b
–
C4
7.54 (d, JZ7.7)a
–
7.42 (m)
C5
–
C6
–
–
C7
3.34(s)
3.31 (s)
C8
–
–
C9
–
–
C10
C11
C12
C13
C14
NH2
7.60 (d, JZ4.9)a
6.58 (t, JZ7.4)
7.20 (t, JZ7.5)b
6.76 (d, JZ8.2)
–
–
6.49 (t, JZ7.1)
7.15 (t, JZ7.71)
6.7 (d, JZ8.1)
–
3.6. Thermal studies
6.22 (s)
6.20 (s)
The thermograms of the representative nickel(II) and
zinc(II) complexes have been recorded. The nickel(II) complex
decomposes in two steps. In the first step, the weight loss of
18.1% (Calcd 18.2%) in the 230–350 8C temperature range is
m, multiplet; d, doublet; t, triplet; s, singlet. *The splitting pattern was obscured
due to the poor solubility of the compound in DMSO.
a
These protons appear as a multiplet in the complex.
b
These protons appear as a triplet in the complex.

28
K.B. Gudasi et al. / Journal of Molecular Structure 788 (2006) 22–29
The ligand ATABZ was found to be less active against all
O
C
the organisms. The complexes were found to be less active
against the fungi PN and AN. In case of bacteria, all the
complexes were found to be moderately active against the
Gram negative bacteria PA and Gram negative BC except
Mn(II) complex which was less active against PA. The
enhanced activity of some complexes, compared to the ligand
and metal salts (inactive) alone has been attributed to the
synergistic effect [30]. According to Tweedy’s chelation theory
[31], on chelation, the polarity of metal ion decreases due to
partial sharing of its positive charge with the ligand, which
further leads to enhancement of lipophilicity of the complex.
Increased lipophilicities allow for penetration of complexes
into, and through the lipid membrane of micro organisms and
inactivation of the enzyme active sites.
O
C
NH2
NH
+
CH3
S
NH2
MeOH
(2-3h.)
11
10
9
7CH3
12
13
3
4
8
5
N
H
C
2
C
N
14
6
S
1
N
O
H
H
Scheme 1.
4. Conclusions
and Bacillus cirroflagellosus (BC) (Gram positive) and the
fungi Aspergillus niger (AN) and Penicillium notatum (PN), by
the cup-plate method [29] and are compiled in Table 6. The
concentration of the compound used for testing was 1 mg/ml in
DMSO. Grisofulvin and Norfloxacin were the standards used
against fungi and bacteria respectively.
Based on the various studies, it is concluded that the ligand
ATABZ reacts with the transition metal salts to give
mononuclear four-coordinate complexes of 1:1 stoichiometry
having the formula [M(ATABZ).Cl2] [Fig. 6] in the case of
cobalt(II), manganese(II), copper(II), nickel(II), zinc(II) and
Fig. 5. 2D HETCORR NMR spectrum of ATABZ (Expanded form is shown in the box inset).

K.B. Gudasi et al. / Journal of Molecular Structure 788 (2006) 22–29
29
Table 6
thankful to Prof S. B. Padhye, University of Pune, India for
magnetic measurement facilities.
Antibacterial and antifungal activity data of ATABZ and its pransition metal
complexes
Compound
Antifungal
PN
Antibacterial
PA
References
AN
BC
[1] Y.P. Kitaev, B.I. Buzykin, T.V. Troepolskaya, Russ. Chem. Rev. 39 (6)
(1970) 441.
ATABZ
C
C
C
C
C
CC
C
CC
(VO(ATABZ)SO4
H2O)
[2] M. Bakir, I. Hassan, T. Johnson, O. Brown, O. Green, C. Gyles,
M.D. Coley, J. Mol. Struct. 688 (2004) 213.
(Mn(ATABZ)) Cl2
(Co(ATABZ)) Cl2
(Cu(ATABZ)) Cl2
(Ni(ATABZ)) Cl2
(Zn(ATABZ)) Cl2
(Cd(ATABZ)) Cl2
Grisofulvin
C
C
C
C
C
C
C
C
C
CC
CC
CC
CC
CC
CC
–
[3] A.E. Dissouky, O.A. Fulij, S.S. Kandil, J. Coord. Chem. 57 (7) (2004).
[4] N. Nawar, N.M. Hosny, Chem. Pharm. Bull. 47 (7) (1999) 944.
[5] M. Vasu, B.H. Doreswamy, K.A. Nirmala, J. Saravanan, S. Mohan,
M.A. Sridhar, J.S. Prasad, Anal. Sci. 20 (2004) 21.
CC
CC
CC
CC
CC
–
C
C
CCC
–
C
C
CCC
–
[6] D.J. Rance, in: L.A. Damani (Ed.), Sulfur-Containing Drugs and Related
Organic Compounds, vol. 1, Ellis Horwood, Chichester, 1989 (part B,
Chapter 9).
Norfloxacin
CCC
–
CCC
–
[7] Shailendra.N. Bharti, F. Naqvi, A. Azam, Bioorg. Med. Chem. Lett. 13 (4)
(2003) 689.
Control
–
–
[8] A. Maiti, S. Ghosh, J. Inorg. Biochem. 36 (1989) 131.
[9] R. Dinda, P. Sengupta, S. Ghosh, H. Mayer-Figge, W.S. Sheldrick,
J. Chem. Soc., Dalton Trans. (2002) 4434.
Key to interpretation: PN, Penicillium notatum; AN, Aspergillus niger; PA,
Pseudomonas aeuregenosa; BC, Bacillus cirroflagellosus; (K)No zone,
inactive; 1–5 mm (C), Less active; 6-10 mm (CC), moderately active; 11–
15 mm (CCC), highly active.
[10] S. Ianelli, P. Mazza, M. Orcesi, C. Pelizzi, G. Pelizzi, F. Zani, J. Inorg.
Biochem. 60 (1995) 89.
[11] M.F. Simeonov, F. Fulop, R. Sillanpaa, K. Pihlaja, J. Org. Chem. 62
(1997) 5089.
CH3
C
[12] K.K. Narang, J.P. Pandey, V.P. Singh, Polyhedron 13 (1994) 529.
[13] G.M. Sheldrick, SHELXL 97 Program for the Solution of Crystal Structures,
¨
University of Gottingen, Germany, 1997.
H
N
C
O
N
S
[14] W.J. Geary, Coord. Chem. Rev. 7 (1971) 81.
[15] C.K. Johnson, ORTEP REPORT ORNL 3794, Oak Ridge National
Laboratory, Tennessee.
NH2
M
[16] S. Ianelli, P. Mazza, M. Orcesi, C. Pelizzi, G. Pelizzi, F. Zani, J. Inorg.
Biochem. 60 (1995) 89.
[17] J.P. Conde, M.R.J. Elsegood, K.S. Ryder, Acta Crystallogr., Sect. C 60
(2004) 166.
X
Y
[18] Y.M. Chumakov, B.Y. Antosyak, M.D. Mazus, V.I. Tsapkov, N.M. Samus,
J. Struct. Chem. 41 (5) (2000) 905.
Fig. 6. Tentative structure of [M(ATABZ).X.Y] complexes XZYZCl in case
of Co(II), Mn(II), Cu(II), Ni(II), Zn(II) and Cd(II). XZH2O, YZSO4 in case of
VO(IV).
[19] D. Kivelson, R. Nieman, J. Chem. Phys. 35 (1961) 149.
[20] B.J. Hathaway, D.E. Billing, Coord. Chem. Rev. 5 (1970) 143.
[21] D. Kivelson, S.K. Lee, J. Chem. Phys. 41 (1964) 1896.
[22] K.K. Nanda, S. Mohanta, S. Ghosh, M. Mukherjee, M. Helliwell, K. Nag,
Inorg. Chem. 34 (1995) 2861.
cadmium(II) and a five-coordinate complex [VO(ATABZ)$
H2O$SO4] in the case of oxovanadium(IV). IR and NMR
spectral studies indicate that the ligand behaves in bidentate
fashion coordinating through carbonyl oxygen and azomethine
nitrogen with the NH2 and thiophene sulphur remaining
unligated. Antimicrobial studies indicate the complexes to be
moderately active against the bacteria whereas they were less
active against the fungi.
[23] C. Ballhausen, H.B. Gray, Inorg. Chem. (1962) 111.
[24] O.P. Pandey, Polyhedron 6 (5) (1987) 1021.
[25] S.K. Sahni, S.P. Gupta, S.K. Sangal, V.B. Rana, J. Indian Chem. Soc.
(1987) 200.
[26] A. El-Dissouky, A.K. Shehata, G. El-Mahdey, Polyhedron 16 (7) (1997)
1247.
[27] SDBS web: http://www.aist.go.jp/RIODB/SDBS (27-8-2004), SDBS No.
730 HSP-40-980.
[28] SDBS web:http://www.aist.go.jp/RIODB/SDBS (2-9-2005) SDBS No.
1647 HSP-04-075.
Acknowledgements
[29] F. Cavanagh, Analytical Microbiology, Academic Press, New York,
1963.
Thanks are due to S.I.F, I.I.Sc., Bangalore, I. I. T., Bombay
and U.S.I.C., Karnatak University, Dharwad for recording
NMR, EPR and UV-VIS spectra, respectively. Authors are
[30] S.S. Kukalenko, B.A. Borykin, S.I. Sheshtakova, A.M. Umelchenko,
Russ. Chem. Rev. 54 (7) (1985).
[31] B.G. Tweedy, Phytopathology 55 (1964) 910.