Synthesis, characterization and physiochemical information, along with antimicrobial studies of some metal complexes derived from an ON donor semicarbazone ligand

Article abstract of DOI:10.1016/j.saa.2010.02.035

Eight new transition metal complexes of benzaldehyde-N(4)-phenylsemicarbazone have been synthesized and characterized by elemental analyses, molar conductance, electronic and infrared spectral studies. In all the complexes, the semicarbazone is coordinate

Full text of DOI:10.1016/j.saa.2010.02.035

Spectrochimica Acta Part A 76 (2010) 22–28
Contents lists available at ScienceDirect
Spectrochimica Acta Part A: Molecular and
Biomolecular Spectroscopy
journal homepage: www.elsevier.com/locate/saa
Synthesis, characterization and physiochemical information, along with
antimicrobial studies of some metal complexes derived from an ON donor
semicarbazone ligand
V.L. Sijia, M.R. Sudarsana Kumara,∗, S. Sumab, M.R. Prathapachandra Kurupc
a Department of Chemistry, M.G. College, Thiruvananthapuram 695004, Kerala, India
b Department of Chemistry, S.N. College, Chempazhanthy, Thiruvananthapuram 695587, Kerala, India
c Department of Applied Chemistry, Cochin University of Science and Technology, Kochi 682022, Kerala, India
a r t i c l e i n f o
a b s t r a c t
Article history:
Eight new transition metal complexes of benzaldehyde-N(4)–phenylsemicarbazone have been synthe-
sized and characterized by elemental analyses, molar conductance, electronic and infrared spectral
studies. In all the complexes, the semicarbazone is coordinated as neutral bidentate ligand. 1H NMR
spectrum of [Zn(HL)2(OAc)2] shows that there is no enolisation of the ligand in the complex. The mag-
netic susceptibility measurements indicate that Cr(III), Mn(II), Fe(III), Co(II) and Cu(II) complexes are
paramagnetic and Ni(II) is diamagnetic. The EPR spectrum of [Mn(HL)2(OAc)2] in DMF solution at 77 K
shows hyperfine sextet with low intensity forbidden lines lying between each of the two main hyper-
fine lines. The g values calculated for the [Cu(HL)2SO4] complex in frozen DMF, indicate the presence of
Received 6 October 2009
Received in revised form 21 February 2010
Accepted 26 February 2010
Keywords:
Benzaldehyde
Semicarbazone
1H and 13C NMR
EPR studies
unpaired electron in the dx
orbital. The metal ligand bonding parameters evaluated showed strong
2
2
−y
in-plane ␴ bonding and in-plane ␲ bonding. The ligand and complexes were screened for their possible
antimicrobial activities.
Antimicrobial studies
© 2010 Elsevier B.V. All rights reserved.
1. Introduction
2. Experimental
The chemistry of transition metal complexes of the semicar-
bazone ligands has been receiving considerable attention because
of their biological relevance [1–7]. Semicarbazones are compounds
with versatile structural features and can coordinate to the metal
either as a neutral ligand or as a deprotonated anion. Semicar-
bazones exist in two tautomeric forms, keto (A) and enol (B)
(Scheme 1). The coordination possibilities in semicarbazones are
increased if the substituents of the aldehyde or ketone include addi-
tional donor atoms. The ␲-delocalization and the configurational
flexibility of their molecular chain can give rise to a great variety of
coordination modes [8].
2.1. Materials
The solvents used for the synthesis of semicarbazone complexes
were purchased from Merck and used without further purifi-
cation. N(4)-Phenylsemicarbazide (Sigma–Aldrich), benzaldehyde
(Merck) were of reagent grade and were used as received. Spectro-
grade solvents were used for spectral recording.
2.2. Synthesis of the semicarbazone (HL)
Herein, we report the synthesis, spectral characterization and
antimicrobial studies of eight metal complexes of benzaldehyde-
N(4)–phenylsemicarbazone. The structure of the semicarbazone
ligand (HL) is given (Scheme 2).
A methanolic solution of N(4)-phenylsemicarbazide (0.151 g,
1 mmol) was refluxed with benzaldehyde (1 mmol) in methanol
containing three to four drops of dilute acetic acid for 3 h
(Scheme 3). On slow evaporation, colorless crystals of the com-
pound separated out. It was filtered, washed with ether and
dried over P4O10 in vacuo. The compound was recrystallized from
methanol (m.p. 176 ◦C, yield 75%). The elemental analysis data
(Table 1) are consistent with the formula of the compound. The
IR, UV–vis., 1H and 13C NMR data of the compound are discussed
along with the complexes.
∗
Corresponding author. Tel.: +91 471 2592617.
E-mail address: sudarsanmr@gmail.com (M.R.S. Kumar).
1386-1425/$ – see front matter © 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.saa.2010.02.035

V.L. Siji et al. / Spectrochimica Acta Part A 76 (2010) 22–28
23
2.4. Physical measurements
Analysis of carbon, hydrogen and nitrogen content of the semi-
carbazone and its complexes were carried out on a Vario EL-III
CHN Elemental Analyzer at the SAIF, Cochin University of Sci-
ence and Technology, India. Infrared spectra were recorded on a
PerkinElmer Infrared Spectrometer using KBr pellets in the range
4000–400 cm−1. Electronic spectra were recorded in methanol on
a Shimadzu UV-2450 UV-visible Spectrophotometer. The 1H and
13C NMR spectra were recorded using Bruker DRX – 500 NMR
Spectrometer, with CDCl3 as solvent and TMS as the standard
at NIIST, Thiruvananthapuram, India. The magnetic susceptibility
measurements were carried out at the Indian Institute of Technol-
ogy, Roorkee, at room temperature in the polycrystalline state on
a PAR model 155 Vibrating Sample Magnetometer at 5 kOe field
strength. EPR spectra of complexes in solid state at 298 K and in
frozen DMF at 77 K were recorded on a Varian E – 112 Spectrom-
eter at X-band, using TCNE as marker with 100 kHz modulation
frequency and 9.1 GHz microwave frequency at the SAIF, IIT, Mum-
bai, India. The molar conductances of the complexes in methanol
solutions (10−3 M) at room temperature were measured using a
Systronics direct reading conductivity meter.
Scheme 1.
Scheme 2.
3. Results and discussion
3.1. Analytical measurements
The colors, partial elemental analyses, molar conductivities and
magnetic susceptibility values are presented in Table 1. The ele-
mental analyses data are consistent with the molecular formula.
The complexes are soluble in DMF, CHCl3 and DMSO. The conduc-
tivity measurements were made in methanol solutions and all the
complexes were found to be non-electrolytes. However, we could
not isolate single crystals of suitable quality for X-ray diffraction
studies for any of these complexes.
Scheme 3.
3.2. Magnetic susceptibilities
2.3. Synthesis of complexes
Room temperature magnetic susceptibility studies reveal com-
plexes 1, 2, 3, 4 and 6 to be paramagnetic. In Cr(III) and Mn(II)
complexes the magnetic moments are found to be 3.29 and
5.12 B.M., respectively. The room temperature magnetic moment
of Mn(II) is consistent with manganese in the +2 oxidation state,
The complexes were prepared by refluxing 1 mmol each of
appropriate salt with 2 mmol of HL in methanol for 5 h. On slow
evaporation, the compounds formed were filtered, washed with
methanol and dried in vacuo over P4O10
.
Table 1
Colors, partial elemental analyses, molar conductivities and magnetic moments of benzaldehyde-N(4)–phenylsemicarbazone and its metal complexes.
Compound
Color
Composition % found (calc)
ꢀma
ꢁbm (B.M.)
Carbon
Hydrogen
Nitrogen
HL
Colorless
Pale blue
Brown
70.24
(70.27)
51.24
(51.28)
58.99
(59.01)
49.53
(49.56)
51.89
(51.93)
39.80
(39.85)
52.63
(52.69)
58.01
5.45
(5.48)
4.74
(4.74)
3.34
(3.38)
3.85
(3.87)
4.63
(4.61)
3.07
(3.11)
4.81
(4.11)
4.13
17.72
(17.56)
8.96
(8.97)
12.88
(12.91)
12.68
(12.39)
10.03
(10.09)
16.63
(16.60)
13.09
(13.17)
12.11
[Cr(HL)(OAc)3] (1)
[Mn(HL)2(OAc)2] (2)
[Fe2(HL)4(SO4)3] (3)
[Co(HL)(OAc)2] (4)
[Ni(HL)(NO3)2] (5)
[Cu(HL)2SO4] (6)
[Zn(HL)2(OAc)2] (7)
[Cd(HL)2(NO3)2] (8)
10.1
10.6
8.3
3.29
5.12
Brown
3.42
Pale green
Brown
13.3
6.1
2.04
Diamagnetic
1.82
Brown
11.3
3.4
Pale yellow
Colorless
Diamagnetic
Diamagnetic
(58.05)
46.91
(4.58)
3.74
(12.69)
15.53
9.3
(47.04)
(3.67)
(15.68)
aMolar conductivity, 10−3 M methanol at 298 K.
bMagnetic susceptibility per metal atom.

24
V.L. Siji et al. / Spectrochimica Acta Part A 76 (2010) 22–28
Fig. 1. Tentative structures of the complexes.
with no significant exchange interactions between adjacent metal
centers [9]. The magnetic moment value of 3.42 B.M. for the Fe(III)
complex indicates a high spin low spin equilibrium [10] at room
temperature. In Co(II) complex, the observed magnetic moment is
much lower than that expected of four coordinate Co(II) tetrahedral
complexes (4.4–4.8 B.M.) [11,12]. This suggests a possible tendency
towards a square planar geometry in the complex. The Ni(II) com-
plex is diamagnetic, consistent with a square planar structure. The
room temperature magnetic susceptibility of the Cu(II) complex in
the polycrystalline state is 1.82 B.M. which is very close to the spin
only value of 1.73 B.M. [13] for a d9 copper system, while the Zn(II)
and Cd(II) complexes are diamagnetic.
3.3. Infrared spectra
Table 2 lists the tentative assignments of main IR bands of
metal complexes for the ligand HL in the 4000–400 cm−1 region.
The spectrum of the ligand exhibits a medium band at 3357 cm−1
which is assigned to ꢂ(4NH) vibration [14]. The medium band
at 2917 cm−1 in the free ligand due to ꢂ(2NH) vibration indi-
cates that the ligand remains in the keto form in the solid state
[15,16]. The presence of this band in the complexes indicates
that there is no enolisation and deprotonation of the ligand and
the semicarbazone is coordinated in the neutral form. A band at
1700 cm−1 in the ligand is shifted to lower frequency in the com-

V.L. Siji et al. / Spectrochimica Acta Part A 76 (2010) 22–28
25
Table 2
Selected IR bands (cm−1) with tentative assignments of benzaldehyde-N(4)–phenylsemicarbazone and its metal complexes.
Compound
ꢂ(C O)
ꢂ(C N)
ꢂ(2NH)
ꢂ(4NH)
ꢂ(N–N)
ꢂ(M–N)
HL
1708
1684
1686
1683
1683
1685
1683
1684
1684
1600
1594
1594
1597
1598
1594
1595
1595
1594
2917
3097
3087
3097
3097
3087
3099
3098
2952
3357
3371
3371
3371
3369
3370
3369
3371
3371
1032
1034
1040
1043
1045
1045
1040
1039
1040
–
483
484
460
485
480
485
487
461
[Cr(HL)(OAc)3] (1)
[Mn(HL)2(OAc)2] (2)
[Fe2(HL)4(SO4)3] (3)
[Co(HL)(OAc)2] (4)
[Ni(HL)(NO3)2] (5)
[Cu(HL)2SO4] (6)
[Zn(HL)2(OAc)2] (7)
[Cd(HL)2(NO3)2] (8)
plexes showing the involvement of C O oxygen in coordination.
The presence of bands in the 1681–1686 cm−1 region for com-
plexes supports the keto form of ligand in all the complexes. A sharp
band at 1600 cm−1 in the semicarbazone can be attributed to the
characteristic >C N–group. This band shift slightly towards lower
frequencies in the complexes [17], indicating the coordination of
azomethine nitrogen to metal. It is further supported by the appear-
ance of new bands at 460–487 cm−1 assignable to ꢂ(M–N) for these
complexes [18]. The ꢂ(N–N) band of semicarbazone is observed
to 1032 cm−1. The increase in the ꢂ(N–N) value in the spectra of
the complexes is due to the increase in double bond character, off-
setting the loss of electron density via donation to the metal and
it is a confirmation of the coordination of the ligand through the
azomethine.
3.4. Electronic spectra
Electronic spectral data of the semicarbazone and its complexes
in methanol solutions are summarized in Table 3. The ␲ → ␲* tran-
sition band in the complexes have shown a bathochromic shift
due to the donation of a lone pair of electrons to the metal and
hence the coordination of azomethine nitrogen. The peak due to
n → ␲* transition is associated with azomethine linkage. These
bands are slightly shifted upon complexation [22]. The charge
transfer bands are observed ∼25,000 cm−1 [23] and their broad-
ness can be explained as being due to the combination of O → M
and N → M LMCT transitions. The spectra of the complexes 1, 2, 3,
4 and 6 exhibit weak d–d bands in the range 13, 700–16, 670 cm−1
[24,25]. Representative spectrum of the semicarbazone ligand HL
is presented in Fig. 2.
In complexes 1, 2, 4 and 7 the asymmetric and symmetric
stretching bands, corresponding to unidentate type of acetate
group [18,19] are present. In complex 6, the spectral data indicates
the bidentate nature of the sulphate anion. In complex 3, the ꢂ1
3.5. 1H NMR spectra
and ꢂ2 vibrations, observed as weak bands at 945 and 465 cm−1
,
The 1H NMR spectrum of the compound HL and its assign-
ments are shown in Fig. 3. A sharp singlet, which integrates as
one hydrogen at ı = 9.51 ppm is assigned to the proton attached
to the nitrogen atom N(2). Another singlet at ı = 7.85 ppm is
assigned to the proton attached to nitrogen atom N(4). The low
suggest the bridged bidentate [20] nature of sulphate anion in the
complex. The symmetry of the sulphate is reduced to C2V when it
functions as a bidentate ligand in the complex. The ꢂ3 vibrations
are observed at 1080, 1143 and 1230 cm−1, while the ꢂ4 vibrations
are observed near 613 and 507 cm−1. In complexes 5 and 8, two
strong bands at 1240 and 1380 cm−1 with a separation of 140 cm−1
corresponding to ꢂ1 and ꢂ4 and a medium band at 1040 cm−1 corre-
sponding to ꢂ2 of the nitrate group indicate the presence of terminal
monodentate nitrate group [18]. ꢂ3, ꢂ5 and ꢂ6 are observed at 748,
720 and 882 cm−1, respectively [21]. The tentative structures of the
complexes are given in Fig. 1.
Fig. 2. Electronic spectrum of ligand HL.
Fig. 3. 1H NMR spectrum of ligand HL.

26
V.L. Siji et al. / Spectrochimica Acta Part A 76 (2010) 22–28
Table 3
Electronic spectral assignments (cm−1) of benzaldehyde-N(4)–phenylsemicarbazone and its metal complexes.
Compound
␲–␲*
n–␲*
LMCT
d–d
HL
41,150
41,320
41,320
48,310
41,490
41,150
47,620
47,170
39,060
34,070
39,600
39,840
39,060
39,680
39,530
45,450
40,000
37,740
–
–
[Cr(HL)(OAc)3] (1)
[Mn(HL)2(OAc)2] (2)
[Fe2(HL)4(SO4)3] (3)
[Co(HL)(OAc)2] (4)
[Ni(HL)(NO3)2] (5)
[Cu(HL)2SO4] (6)
[Zn(HL)2(OAc)2] (7)
[Cd(HL)2(NO3)2] (8)
23,390
22,680
26,040
22,830
26,250
24,940
30,390
31,750
15,650
13,470
16,670
13,700
–
14,630
–
–
field position of –N(4)H can be attributable to the deshielding
caused by phenyl group. This downfield shift also explained the H-
bonding interaction with nitrogen atom N(1). Hydrogen bonding
decreases the electron density around the proton and thus moves
the proton absorption to a lower field. Absence of any coupling
interaction by N(2)H and N(4)H protons due to lack of availabil-
ity of protons on neighbouring atoms render singlet peaks for the
imine protons. The ligand does not show any peak attributable to
–OH proton indicating that it exists in the keto form. IR spectral
data are also in confirmity with these observations. A signal at
ı = 8.18 ppm is assigned to –CH N– proton. The more downfield
shift of–CH N–can be attributed to the increased charge den-
sity on N(1) resulted by its hydrogen bonding to N(4)H and also
due to electronic effect of the adjacent electronegative nitrogen.
Aromatic protons of both phenyl rings appear with in the range
7.09–7.68 ppm with coupling constant 7 Hz.
different resonant peaks to respective carbon atoms is presented in
Fig. 5. There are 9 unique carbon atoms in the molecule which give a
total of 9 different peaks in the 13C NMR spectrum. The C(8) carbon
atom resonance is observed farthest downfield at ı = 153.61 ppm
resultant of the conjugative effect of the –N(1)–N(2)–CO–N(4)–
semicarbazone skeleton. The protonated carbon atom at C(7) show-
ing more downfield shift in the spectrum (ı = 141.78 ppm), due to
an increase in electron density resulting from the presence of elec-
tronegative atom and ␲ electron delocalization on the C(7) N(1)
bond. In N(4) phenyl ring the C(9) carbon atom adjacent to more
electronegative nitrogen atom N(4) are shifted farther downfield of
ı = 137.84 ppm when compared to the neighbouring carbon atoms.
The N(4) phenyl resonances are C(9), 137.84 ppm; C(10) and C(14),
128.79 ppm; C(11) and C(13), 130.02 ppm; C(12), 129.02 ppm.
Aromatic carbons of the benzaldehyde ring are observed C(1),
133.66 ppm; C(2) and C(6), 119.68 ppm; C(3) and C(5), 126.94 ppm;
C(4), 123.54 ppm.
The 1H NMR spectrum of Zn(II) complex is shown in Fig. 4. A
singlet at ı = 10.11 ppm is assigned to the proton attached to the
nitrogen atom N(2). Another singlet at ı = 7.88 ppm is assigned to
the N(4) proton. The presence of the signal due to N(2)H in the
Zn(II) complex indicates that there is no enolisation of ligand in
the complex. The spectrum of the complex shows a sharp singlet
which integrate as one hydrogen at ı = 8.20 ppm corresponds to
–CH N– present in semicarbazone moiety. In the 1H NMR spec-
trum of ligand, a strong signal due to –CH N– of ligand undergoes
downfield shift on complexation, indicating the participation of
azomethine nitrogen on bonding. The resonance for the two C6H5–
groups appear as multiplets with in the range 7.08–7.67 ppm with
coupling constant 7 Hz.
3.6. 13C NMR spectrum
The 13C NMR spectrum provides direct information about the
carbon skeleton of the semicarbazone ligand HL. Assignment of
Fig. 4. 1H NMR spectrum of [Zn(HL)2(OAc)2].
Fig. 5. 13C NMR spectrum of HL.

V.L. Siji et al. / Spectrochimica Acta Part A 76 (2010) 22–28
27
Fig. 6. EPR spectrum of [Cu(HL)2SO4] in DMF solution at 77 K.
3.7. EPR spectrum of the Cu(II) complex
The EPR spectrum of the Cu(II) complex in the polycrystalline
state at 298 K and in DMF at 77 K (Fig. 6) were recorded in the X-
band using 100 kHz field modulation and the g factors were quoted
relative to the standard marker DPPH (polycrystalline state, 298 K,
g = 2.0036) and TCNE (DMF, 77 K, g = 2.00277). The EPR parameters
of the copper(II) complex are presented in Table 4.
The EPR spectrum of the copper complex in the polycrystalline
state (298 K) and in DMF (77 K) show typical axial behaviour with
slightly different g and g values. The geometric parameter G,
||
⊥
which is a measure of the exchange interaction between the cop-
per centers in the polycrystalline compound, is calculated using the
equation G = (g − 2.0023)/(g⊥ − 2.0023) for axial spectrum. If G < 4,
Fig. 7. EPR spectra of [Mn(HL)2(OAc)2] in polycrystalline state at 298 K and DMF at
77 K.
||
considerable exchange interaction is indicated in the solid com-
plex [26]. If G > 4, the exchange interaction is negligible [27]. For
the complex [Cu(HL) SO ], the g > g > 2.0023 and G value is 2.98
||
⊥
2
4
where ꢀ0 is the spin orbit coupling constant and has the value
−828 cm−1 for a Cu(II) d9 system.
are consistent with a dx
The EPR spectrum of the complex in the DMF solutions at 77 K
is axial with four hyperfine lines in the parallel regions. For the
ground state.
2
2
−y
Hathaway [29] has pointed out that for pure ␴ bonding
K ≈ K⊥ ≈ 0.77 and for in-plane ␲-bonding, K < K , while for out-
||
||
⊥
spectra of the complex in frozen DMF, the g > g values rules out
||
⊥
of-plane ␲-bonding K < K . In all the complexes, it is observed
⊥
||
the possibility of trigonal bipyramidal structures for which g > g is
⊥
||
that K < K which indicates the presence of significant in-plane
||
⊥
expected. The EPR parameters g , g , gav, A (Cu) and the energies of
||
⊥
||
␲-bonding. Furthermore ˛2, ˇ2 and ꢃ2 have values less than 1.0,
which is expected for 100% ionic character of the bonds and become
smaller with increasing covalent bonding. Therefore the evaluated
values of ˛2, ˇ2 and ꢃ2 of the complexes are consistent with both
d–d transition were used to evaluate the bonding parameters. ˛2,
ˇ2 and ꢃ2, which may be regarded as measures of the covalency
of the in-plane ␴ bonds, in-plane ␲ bonds and out-plane ␲ bonds,
respectively. The value of in-plane sigma bonding parameter ˛2
was estimated from the following expression:
in-plane ␴ and in-plane ␲-bonding. The fact that the g values are
||
less then 2.3 is an indication of significant covalent character to the
M–L bond [13,30].
−A
3
7
||
2
˛
=
+ (g|| − 2.00277) + (g⊥ − 2.00277) + 0.04
0.036
3.8. EPR spectrum of the Mn(II) complex
The orbital reduction factors K = ˛2ˇ2 and K = ˛2ꢃ2 were cal-
culated using the following expressions [28]:
||
⊥
The X-band EPR spectra of manganese complex in the polycrys-
talline state at 298 K and DMF at 77 K are given in Fig. 7. The solid
state EPR spectrum of the manganese complex at 298 K is char-
acterized by broad signal with g value of 2.003. The signal of the
spectrum observed is broadened due to dipolar interaction and a
random orientation of Mn2+ ions. In the spectrum from DMF solu-
tions at 77 K, a hyperfine sextet is observed with g value 2.001
(g|| − 2.00277)Ed−d
K|2|
=
=
8ꢀ0
(g⊥ − 2.00277)Ed−d
2ꢀ0
K⊥2
Table 4
EPR parameters of Cu(II) complex in polycrystalline state at 298 K and DMF solution at 77 K.
Compound
Polycrystalline state (298 K)
DMF solution (77 K)
a
2
2
g
||
g
⊥
gav
G
g
||
g
⊥
gav
A
||
˛
ˇ2
␥
K
||
K
⊥
[Cu(HL)2SO4]
2.181
2.062
2.102
2.98
2.295
2.088
2.157
166.67
0.86
0.92
0.99
0.80
0.86
a
Expressed in units of cm−1 multiplied by a factor of 10−4
.

28
V.L. Siji et al. / Spectrochimica Acta Part A 76 (2010) 22–28
and Aiso value 96 G, respectively. The six hyperfine lines are due
to the interaction of the electron spin with nuclear spin (55Mn,
I = 5/2). In addition to this, a pair of low intensity forbidden lines
lying between each of the two main hyperfine lines with an aver-
age spacing of 23 G is observed corresponding to ꢄmI = 1 [31].
The forbidden lines in the spectrum arise due to the mixture of
the nuclear hyperfine levels by the zero-field splitting factor of the
Hamiltonian [32,33].
The observed g value is very close to the free electron spin
value of 2.0023, suggestive of the absence of spin orbit coupling
in the ground state. The Aiso values are consistent with an octa-
hedral coordination [34], since Aiso in tetrahedral sites is 20–25%
lower than in octahedral sites. The Aiso values are some what lower
than pure ionic compounds, which reflect the covalent nature of
the metal–ligand bond in the complex.
Acknowledgements
One of the authors, VLS is thankful to the Council of Scientific and
Industrial Research (CSIR), New Delhi for the financial assistance in
the form of Junior Research Fellowship. The authors are thankful
to the SAIF, Cochin University of Science and Technology, Kochi,
India for elemental analyses, IIT Roorkee for magnetic susceptibility
measurements, NIIST, Thiruvananthapuram for 1H and 13C NMR
data and SAIF, IIT, Mumbai, India for EPR spectral studies.
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All complexes (1–8) along with their parent semicarbazone lig-
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585, Salmonella typhi MTCC 734, Proteus vulgaris MTCC 1771, Enter-
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734 (7.5 mm), Proteus vulgaris MTCC 1771 (10.5 mm) and
[Ni(HL)(NO3)2] was found to be active against E. coli MTCC 585
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