Synthesis and characterization of some bi, tri and tetravalent transition metal complexes of N′-(furan-2-yl-methylene)-2-(p-tolylamino) acetohydrazide HL1 and N′-(thiophen-2-yl-methylene)-2-(p- tolylamino)acetohydrazide HL2

Article abstract of DOI:10.1016/j.saa.2012.02.045

The tetradentate Schiff bases hydrazone ligands HL¹, HL ² and their metal complexes have been prepared and characterized by analytical, spectral (IR, UV-vis, ¹H NMR and ESR), molar conductivity, magnetic and TGA measurements. The results show that all the metal complexes are non-electrolytes, except (2, 10 and 20) which have ionic nature. The ligands coordinate in keto-neutral form and act as bidentate or tridentate for all metal complexes, except complexes (4 and 12). The ligands react as monobasic tetradentate and tridentate for complexes (4 and 12), respectively. Octahedral/tetrahedral Co(II) and Ni(II), octahedral/square planar Cu(II), and octahedral Mn(II), Fe(III), Cr(III), Ru(III), Hf(IV) and Zr(IV)O geometries were proposed. The ESR spectra of copper complexes (12 and 14) indicate d( ^x2-^y2) ground state with covalent bond character. The thermal decomposition and the types of crystallized water for some metal complexes were studied. The studied metal complexes are very weakly active against the tested microorganisms.

Full text of DOI:10.1016/j.saa.2012.02.045

Spectrochimica Acta Part A 92 (2012) 96–104
Contents lists available at SciVerse ScienceDirect
Spectrochimica Acta Part A: Molecular and
Biomolecular Spectroscopy
journal homepage: www.elsevier.com/locate/saa
Synthesis and characterization of some bi, tri and tetravalent transition metal
complexes of Nꢀ-(furan-2-yl-methylene)-2-(p-tolylamino)acetohydrazide HL1
and Nꢀ-(thiophen-2-yl-methylene)-2-(p-tolylamino)acetohydrazide HL2
S.M. Emam, S.A. AbouEl-Enein∗, F.A. El-Saied, S.Y. Alshater
Chemistry Department, Faculty of Science, El-Menoufia University, Shebin El-Kom, Egypt
a r t i c l e i n f o
a b s t r a c t
The tetradentate Schiff bases hydrazone ligands HL1, HL2 and their metal complexes have been prepared
and characterized by analytical, spectral (IR, UV–vis, 1H NMR and ESR), molar conductivity, magnetic
and TGA measurements. The results show that all the metal complexes are non-electrolytes, except (2,
10 and 20) which have ionic nature. The ligands coordinate in keto-neutral form and act as bidentate
or tridentate for all metal complexes, except complexes (4 and 12). The ligands react as monobasic
tetradentate and tridentate for complexes (4 and 12), respectively. Octahedral/tetrahedral Co(II) and
Ni(II), octahedral/square planar Cu(II), and octahedral Mn(II), Fe(III), Cr(III), Ru(III), Hf(IV) and Zr(IV)O
Article history:
Received 22 December 2011
Received in revised form 9 February 2012
Accepted 10 February 2012
Keywords:
Metal complexes
Schiff bases hydrazones
Spectral measurements
Magnetic moment
Thermogravimetric analysis (TGA)
Biological activity
geometries were proposed. The ESR spectra of copper complexes (12 and 14) indicate d(x
ground
2
2
)
−y
state with covalent bond character. The thermal decomposition and the types of crystallized water for
some metal complexes were studied. The studied metal complexes are very weakly active against the
tested microorganisms.
© 2012 Elsevier B.V. All rights reserved.
1. Introduction
antibacterial and antifungal tests of some metal complexes were
also carried out.
Schiff bases hydrazone derivatives and their metal complexes
have been studied for their interesting and important properties,
e.g., antibacterial [1,2], antifungal [3], antioxidant [4], anticancer
[5] and catalytic activity in oxidation of cyclohexene [6]. Moreover,
Schiff bases hydrazone derivatives are versatile ligands and they
offer the possibility of different modes of coordination towards
transition metal ions. Also, some of these derivatives have been
applied as iron chelator drugs in therapy of anemia [7] and treat-
ment of neuropathic pain [8].
Therefore it prompted us to continue our previous work
on characterization of some transition metal complexes of
aromatic and heterocyclic N-anilinoacetohydrazone [1,9,10].
The present investigation deals with synthesis and char-
acterization of Mn(II), Co(II), Ni(II), Cu(II), Cr(III), Fe(III),
Ru(III), Hf(IV) and Zr(IV)O metal complexes of Nꢀ-(furan-
2. Experimental
2.1. Materials
p-Toludine, ethylchloroacetate, sodium acetate trihydrate,
hydrazine hydrate, 2-furylaldehyde, 2-thiophenealdehyde, abso-
lute ethyl alcohol and metal chloride salts of Cu(II), Ni(II), Mn(II),
Cr(III), Fe(III), Ru(III), Hf(IV) and Zr(IV)O, acetate salts of Cu(II),
Co(II), Ni(II), Mn(II) and nitrate salts of Cu(II) and Co(II) were used
without further purification.
2.2. Synthesis of ligands
HL1
and
The ethyl[(4-methylphenyl)amino]acetate was prepared by
refluxing equimolar amounts of a hot ethanolic solution of p-
toludine, ethylchloroacetate and sodium acetate trihydrate for 6 h.
The mixture was poured on cold water and stirred for 30 min. The
formed precipitate was filtered off, washed with ethanol and dried
over anhydrous CaCl2, m.p. = 43 ◦C [11].
2-yl-methylene)-2-(p-tolylamino)acetohydrazide,
Nꢀ-(thiophen-2-yl-methylene)-2-(p-tolylamino)acetohydrazide,
HL2. Analytical, spectral, magnetic, molar conductivity and
thermogravimetric analysis (TGA) were used to investigate the
chemical structure of these ligands and their metal complexes. The
The 2-[(4-methylphenyl)amino]acetohydrazide was synthe-
sized by adding ethanolic solution of hydrazine hydrate drop wise
to an equimolar amount of ethyl[(4-methylphenyl)amino]acetate
in ethanol, with stirring and heating. A white precipitate was
∗
Corresponding author.
E-mail address: dr.saeyda elenein@yahoo.com (S.A. AbouEl-Enein).
1386-1425/$ – see front matter © 2012 Elsevier B.V. All rights reserved.
doi:10.1016/j.saa.2012.02.045

S.M. Emam et al. / Spectrochimica Acta Part A 92 (2012) 96–104
97
formed after about 3 h. The precipitate was filtered off, washed
several times with ethanol and dried over anhydrous CaCl2,
m.p. = 162 ◦C [10,11].
nitrogen atmosphere using a Shimadzu DT-50 thermal analyzer
from room temperature to 800 ◦C at a heating rate of 10 ◦C/min.
The Schiff bases ligands Nꢀ-(furan-2-yl-methylene)-2-
3. Results and discussion
(p-tolylamino)acetohydrazide
HL1
and
Nꢀ-(thiophen-2-
HL2
were
yl-methylene)-2-(p-tolylamino)acetohydrazide
3.1. The ligands
prepared by refluxing equimolar amounts of 2-[(4-
methylphenyl)amino]acetohydrazide with 2-furylaldehyde or
2-thiophenealdehyde in 50 mL absolute ethanol for 3 h. The
formed solid buff precipitate was filtered off and washed with
ethanol. The product was crystallized from ethanol and finally
dried over anhydrous CaCl2. Melting points are 162 and 140 ◦C for
HL1 and HL2, respectively.
The prepared ligands HL1 and HL2 were investigated by elemen-
tal analyses (Table 1), 1H NMR and IR spectra (Table 2).
The 1H NMR spectra of ligands HL1 and HL2 were carried out at
room temperature in DMSO-d6 and CDCl3, respectively. The spec-
tra exhibit the signals at 3.40–3.75, 4.20–4.3 and 6.38–7.4 ppm
corresponding to methyl group, methylene and aromatic protons
(multiples), respectively [16]. The signal of azomethine appears at
7.87–7.97 ppm as a singlet [1,16] and the imide HN CO signal of the
keto form was observed at 9.9–10.8 ppm [17], whereas the signal
at 8.43–8.6 ppm was assigned to ph-NH [18]. The spectrum of HL1
reveals OH signal at 12.38 ppm, indicating a keto–enol tautomerism
[9,17].
2.3. Synthesis of metal complexes
All the metal complexes were prepared by adding the appro-
priate metal salts (0.01 mol in 20 mL ethanol) to a hot solution
of ligands HL1 or HL2 (0.01 mol in 50 mL ethanol). The reaction
mixture was magnetically stirred and refluxed for about 3 h. The
separated complex was filtered off, washed several times with
ethanol and finally dried under vacuum over anhydrous calcium
chloride.
The infrared spectra of ligands (Table 2) showed bands at
3388–3118, 1676, 1619–1616, 587 and 577 cm−1, assigned to
ꢀ(N H), ꢀ(C O), ꢀ(HC N), furan and thiophene ring bending,
respectively. The elemental analyses (Table 1), infrared and 1H NMR
data are compatible with the structure shown below:
H3C
2.4. Screening for the antimicrobial activity
The antibacterial activities of metal complexes (10, 12, 14–16
and 19) of HL2 ligand were evaluated against gram negative bac-
teria (Escherichia coli and Klebsiella pneumonia) and gram positive
bacteria (Bacillus cereus and Staphylococcus aureus) and Candida
albicans (as fungs) using the modified disc diffusion method [12].
A nutrient agar (NA) medium was used for bacteria and Sabouroud
agar slop was used for fungs. Stock solution of tested compounds
was prepared in DMSO at different concentrations (0.25, 0.50, 1.00
and 10.00 mg/mL). To ensure that the solvent had no effect on the
growth of microorganisms, a control test was performed with test
medium supplemented with DMSO with the same procedures used
in the experiments. Ampicillin trihydrate and clorimazole were also
screened under similar conditions as reference antibacterial and
antifungal drugs, respectively. Minimum inhibitory concentrations
(MICs) were determined by the micro-dilution broth method fol-
lowing the procedures recommended by the National Committee
for Clinical Laboratory Standards [13,14]. MICs were defined as the
lowest concentrations of compounds which inhibit the growth of
microorganisms.
X
HN
CH2
HC
N
X= O : HL1
X= S : HL2
O
NH
3.2. Metal complexes and characterization
The analytical data of ligands and their metal complexes
(Table 1) showed that the reaction of ligand HL1 or HL2 with
various metal salts in the (1M:1L) molar ratio gives complexes
with different stoichiometric 1:1, 1:2 and 2:1 (M:L). All the metal
complexes derived from HL1 and HL2 are separated with (1M:1L)
molar ratio except the chromium chloride, cobalt nitrate (11) and
cobalt chloride complexes of HL2 and HL1, respectively, which are
formed with (1M:2L) molar ratio. While the binuclear nickel com-
plex [Ni2(L1)(OAc)3(H2O)3] is raised from the reaction of 1 mol
nickel acetate with 1 mol HL1 ligand. The metal complexes are
stable, nonhygroscopic, partially soluble in most organic solvents
and soluble in DMF and DMSO. The molar conductivity values for
all metal complexes were measured in (1 × 10−3 M) DMF solution
at 25 ◦C (Table 1). The data showed that the molar conductivities
of [Co(HL1)2]Cl2·H2O, [Co(HL2)2]Cl2·H2O and [Cr(HL2)2Cl2]Cl·EtOH
complexes are 101.5, 105.2 and 80.9 ꢁ−1 mol−1 cm2, respectively.
The results indicate that these complexes are ionic in nature and
are of the types 2:1 and 1:1 electrolytes, respectively [18,19]. How-
ever, the rest of the other metal complexes have small conductance
values, indicating that they are non-electrolytes [10,20]. The high
molar conductivities of non-electrolytes are due to partial displace-
ment of the anion by DMF molecules [21].
2.5. Instruments
Elemental microanalyses (C, H, N and Cl) were performed at the
Microanalytical Unit, Cairo University. IR spectra were recorded as
KBr discs using a Perkin-Elmer 1430 spectrophotometer. The elec-
tronic spectra were measured in nujol mull using a Perkin-Elmer
Lambda 4B spectrophotometer. 1H NMR spectra were carried out in
deutrated DMSO and deutrated chloroform (CDCl3), using 300 MHz
Varian NMR spectrophotometer. The electron spin resonance (esr)
spectra were obtained in the X-band at room temperature on
Bruker Elexsys 500 E spectrometer with a microwave frequency
9.82 GHz and a modulation frequency 10 kHz. The magnetic sus-
ceptibilities were measured at room temperature by a modified
Gouy method using a Johnson Matthey magnetic susceptibility bal-
ance. Diamagnetic corrections were made using Pascal’s constant
[15]. Molar conductivity measurements in DMF (1 × 10−3 M) were
measured at room temperature on CM-1K portable conductivity
meter. The thermogravimetric analysis (TGA) was carried out under
3.2.1. Infrared spectra
The infrared spectral bands with their assignments for the free
ligands and their metal complexes are listed in Table 2. The spec-
tra of the free ligands display bands in the range 3392–3118 cm−1
,
assigned to different vibration mode of NH group [20,22]. The
bands at 3218–3118 cm−1 are not greatly affected in complexes

98
S.M. Emam et al. / Spectrochimica Acta Part A 92 (2012) 96–104
Table 1
Elemental analyses, molar conductivities and colors of ligands and their metal complexes.
No.
Compound
Color, F.W.
Found (Calc)%
C
ꢂ-a
M
H
N
Cl
–
HL1
C14H15N3O2
Buff
66.20
(65.36)
42.90
(43.50)
50.90
(50.70)
37.40
(36.63)
39.70
(39.66)
40.00
(40.10)
45.60
(46.37)
40.40
(40.07)
35.20
(34.77)
60.50
(61.50)
41.10
(41.39)
48.70
(48.42)
51.19
(51.15)
43.40
(42.82)
36.61
(36.41)
37.28
(37.24)
44.90
(44.49)
31.17
(31.80)
44.11
(44.83)
36.20
(36.37)
35.75
(35.65)
48.60
(48.00)
35.40
(35.71)
28.40
5.40
(5.88)
4.70
(5.67)
5.00
(4.87)
5.40
(5.05)
5.20
(4.83)
5.00
(4.57)
4.80
(5.40)
3.80
(3.60)
3.40
(3.54)
6.20
(5.50)
5.40
(5.60)
5.20
(4.64)
4.80
(5.21)
4.93
(5.16)
4.20
(4.58)
3.9
(3.75)
5.00
(5.18)
4.95
(5.53)
4.40
(5.23)
3.90
(4.76)
3.99
(4.06)
4.80
(4.83)
3.80
(3.60)
4.70
15.70
(16.33)
8.90
(8.45)
11.80
(12.70)
8.90
(9.15)
7.40
(6.94)
9.90
(10.02)
8.70
(9.01)
9.50
(10.01)
9.0
(8.70)
16.20
(15.38)
7.90
(8.05)
11.70
(12.10)
13.14
(12.80)
9.60
(9.36)
8.80
(9.1)
15.00
(14.47)
8.45
(8.65)
8.20
(7.94)
8.45
(8.71)
8.79
–
257.30
Brown
497.23
Deep brown
662.53
Green
459.01
Brown
604.712
Green
419.23
Brown
466.23
Brown
419.64
Brown
483.57
Buff
273.30
Blue
522.23
Blue
694.53
Brown
657.53
Buff
448.83
Brown
461.84
Green
1
2
3
4
5
6
7
8
[Co(HL1)(OAc)2(H2O)2]·1.5H2O
–
3.80
101.50
23.40
8.20
C
18H28CoN3O9.5
[Co(HL1)2]Cl2·H2O
C28H32Cl2CoN6O5
11.00
(10.72)
16.00
(15.46)
–
[Ni(HL1)Cl2(H2O)2]·2H2O
C14H23Cl2NiN3O6
[Ni2(L1)(OAc)3(H2O)3]
C20H29Ni2N3O11
[Mn((HL1)Cl2(H2O)2]
C14H19Cl2MnN3O4
[Mn((HL1)(OAc)2(H2O)2]
C18H25MnN3O8
16.60
(16.94)
–
13.50
34.00
20.10
32.70
–
[Fe((HL1)Cl3]
25.00
(25.38)
22.50
(22.02)
–
C14H15Cl3FeN3O2
[Ru((HL1)Cl3(H2O)]
C14H17Cl3RuN3O3
HL2
C14H15N3OS
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
[Co(HL2)(OAc)2]·4H2O
C18H29CoN3O9S
[Co(HL2)2]Cl2·H2O
–
3.40
9.80
(10.22)
–
105.20
10.30
8.50
C28
H
32Cl2CoN6O3S2
[Co(HL2)2(OH)2]·H2O
C28H34CoN6O5S2
[Cu(L2)(OAc)(H2O)2]·H2O
C16H23CuN3O6S
–
[Cu(HL2)Cl2(H2O)2]·H2O
C14H21Cl2CuN3O5S
14.90
(15.36)
–
9.50
[Cu(HL2)(NO3)2]·0.5EtOH
4.90
C
15H18CuN5O7.5
S
483.84
Buff
[Ni(HL2)(OAc)2(H2O)2]
C18H25NiN3O7S
–
486.01
Brown
529.01
Pale brown
482.23
Brown
462.34
Deep brown
471.64
Brown
751.10
Brown
504.57
Brown
577.52
Brown
628.79
[Ni(HL2)Cl2]·7H2O
13.00
(13.42)
–
32.10
7.4
C14
H29Cl2NiN3O8S
[Mn(HL2)(OAc)2(H2O)2]
C18H25MnN3O7S
[Mn(HL2)Cl2(H2O)2]·1.5H2O
16.00
(15.36)
22.00
(22.58)
13.85
(14.18)
20.70
(21.1)
11.70
(12.29)
10.90
26.7
3.5
C14H22Cl2MnN3O4.5
[Fe(HL2)Cl3]·2H2O
C14H19Cl3FeN3O3S
S
(9.09)
8.50
(8.91)
11.60
(11.17)
8.21
(8.33)
7.60
(7.27)
6.46
[Cr(HL2)2Cl2]Cl·EtOH
80.9
25.3
20.3
22.5
C
30H36Cl3CrN6O3S2
[Ru(HL2)Cl3]·0.5EtOH
C15H18Cl3RuN3O1.5
S
[ZrO(HL2)Cl2(H2O)2]·5H2O
C14H29Cl2ZrON3O8S
(29.12)
27.20
(26.74)
(5.00)
4.20
(4.01)
[Hf(HL2)Cl2(OH)2]·4H2O
C14H25Cl2HfN3O7S
(6.68)
(11.29)
a
ꢁ
−1 mol−1 cm2.
(1, 4, 6, 8, 9, 10, 12, 13, 14, 16, 18, 21 and 22), whereas the higher
wave number bands at 3392–3388 cm−1 appeared at different posi-
tions with a very broad nature due to overlapping with ꢀ(OH)
of water of crystallization [20,23]. The infrared spectra of metal
complexes (1, 8, 10, 13, 14 and 18) show shift to lower wave num-
ber for ꢀ(C O) and ꢀ(HC N). This is consistent with coordination
of carbonyl oxygen and azomethine nitrogen atoms [9,24]. The
ꢀ(HC N) band of free ligand (1619 cm−1) exhibits a bathchromic
shift of 19–51 cm−1 for complexes (2, 6, 9, 17 and 22). Also, the
vibrations due to hetero-ring atoms undergo hypsochronic shift of
28–45 cm−1 upon complexation. The spectra of these complexes
show that the ꢀ(C O) remains unchanged. The above arguments
indicate that the ligands in these complexes behave as neutral
bidentate and coordination occurs via the azomethine nitrogen
atom and the hetero-oxygen or sulphur atoms.
(11, 15, 20 and 23). On the other hand, the vibration of NH and
(HC N) is perturbed upon complexation, which indicate that the
coordination takes place via anilino nitrogen atom and azomethine
nitrogen atom.
The complexes (7, 16, 19 and 21) show that the ꢀ(C O) of free
ligands HL1 or HL2 were shifted to lower frequency by 18–40 cm−1
,
whereas the hetero-ring bending exhibited positive or negative
shifts by 11–25 cm−1 upon complexation. Moreover, the band due
to ꢀ(HC N) of free ligands is strongly affected in shape and position
upon complexation. The above discussion reveals that the metal
ions (except Ni(II)) form neutral coordination compounds through
carbonyl oxygen, azomethine nitrogen and hetero-atoms. How-
ever, for Ni(II) complex (16) the ligand was binding with Ni(II) ion
through azomethine nitrogen atom and carbonyl oxygen atom or
hetero-atom.
The absorption band due to ꢀ(C O) at 1676 cm−1 and the thio-
phene ring bending band at 577 cm−1 of free ligand HL2 appear at
the same position or are slightly affected upon complexation for
The infrared spectra of complexes (3 and 5) display that the
bands due to ꢀ(HC N) and hetero-atom do not participate in coor-
dination. While, the ꢀ(C O) band shows shift to higher frequency

S.M. Emam et al. / Spectrochimica Acta Part A 92 (2012) 96–104
99
Table 2
Infrared spectral bands and their assignments for ligands and their metal complexes.
No.
Compound
HL1
ꢀ(H2O)
ꢀ(NH)
ꢀ(C O)
ꢀ(C N)
R.b. F/S
587(m)
ꢀ (M O)
ꢀ(M N)
ꢀ(M S)
ꢀ(Anion)
–
3392(s),
3200(s),
3118(w)
3390(b),
3200(w),
3120(w)
3354(s),
3215(w),
3130(w)
3391(s.b),
3250(sb),
–
1673(vs)
1619(s)
–
–
–
–
1
2
3
4
[Co(HL1)(OAc)2(H2O)2]·1.5H2O
[Co(HL1)2]Cl2·H2O
3440(w)
671*
1615(w)
1673(m)
1701(s)
–
1550(w)
1568(m)
1616(s)
583(w)
632(w)
588(m)
628
515(w)
518(m)
512(w)
540
450(sh)
450(sh)
430(w)
460(w)
–
–
–
–
(1600,
1400)b
3461(s)
330(w)a
[Ni(HL1)Cl2(H2O)2]·2H2O
[Ni2(L1)(OAc)3(H2O)3]
3500
666*
330(w)a
3480(w)
676*
–
1605,
1545
(1600,
1417)b
3200(b),
3118(w)
–
5
6
[Mn((HL1)Cl2(H2O)2]
3375(s)
667*
3430
668*
1701(s)
1673(s)
1615(s)
1568(s)
586(w)
510(w)
517(w)
445(sh)
485(w)
–
–
330(w)a
[Mn((HL1)(OAc)2(H2O)2]
3392,
3200(m),
–
615,
590(w.sp)
(1600,
1392)b
7
8
[Fe((HL1)Cl3]
–
3420,
1655(w)
1655(m)
1610(w)
1600(w)
619,
576(sh)
505(m)
546(w)
410(s)
–
–
371(s)a
371(w)a
–
3250(sh),
3125(sh)
3390(w),
3202(w),
3123(w)
3388(m),
3218(w)
–
3222(sh)
–
3209(sh)
–
[Ru((HL1)Cl3H2O]
643*
589(m)
450(w)
HL2
–
1676(s)
1676(m)
1649(s)
1674(s)
1619(m)
1600(sh)
1600(sh)
1610(m)
577(m)
616(w)
583(m)
580(m)
–
–
–
9
10
11
[Co(HL2)(OAc)2]·4H2O
[Co(HL2)2]Cl2·H2O
[Co(HL2)2(OH)2]·H2O
3442(b)
3423(b)
3420(s)
518(w)
516(w)
520(s)
450(w)
455(w)
435(m)
437(w)
(1515,
1330)b
327(w)a
–
–
–
3185,
3167(w.sp)
–
3220(sh)
–
3213(w)
–
12
13
14
15
16
17
18
19
21
21
22
23
[Cu(L2)(OAc)(H2O)2]·H2O
[Cu(HL2)Cl2(H2O)2]·H2O
[Cu(HL2)(NO3)2]·0.5EtOH
[Ni(HL2)(OAc)2(H2O)2]
[Ni(HL2)Cl2]·7H2O
3427(b)
3442(b)
3442(b)
3449(b.w)
3400(w)
3420
–
1610(w)
1595(sh)
1595(sh)
614(m)
584(m)
579(w)
581(m)
602(w)
581(m)
582(m)
564(m)
583(w)
588(w)
615(w)
579(w)
515(w)
518(w)
530(m)
522(s)
490(s)
517(w)
513(sh)
508(m)
–
464(w)
464(w)
415(w)
(1580,
1388)b
380(w)a
1655(s)
1651(m)
1674(s)
1635(w)
1677(m)
1631(w)
1649(m)
1676(s)
1654(m)
1679(w)
1673(m)
–
1608(w)
1610(m)
1610(w)
1555(b)
1590(w)
1587(m)
1608(w)
1620(w)
1594(w)
489(m)
420(w)
430(w)
–
(1389,
1300)c
(1584,
1402)b
–
3200(w)
3403(s),
3167(w)
3358(b),
3197(sh)
3383(w),
3222(w)
–
3222(sh)
3304(m),
3222(w)
–
3170(w)
3317(w.b),
3200(m)
3197(w)
3187(w)
–
–
452(w)
470(sh)
462(sh)
470(sh)
495(w)
466(w)
464
415(w)
[Mn(HL2)(OAc)2(H2O)2]
[Mn(HL2)Cl2(H2O)2]·1.5H2O
[Fe(HL2)Cl3]·2H2O
–
(1600,
1344)b
372(w)a
3413(b)
3418(b)
3404(m)
3422(b.w)
–
436
–
[Cr(HL2)2Cl2]Cl·EtOH
–
–
[Ru(HL2)Cl3]·0.5EtOH
[ZrO(HL2)Cl2(H2O)2]·5H2O
[Hf(HL2)Cl2(OH)2]·4H2O
490(w)
–
417(w)
417(w)
–
–
3180(b)
653*
3403(m)
–
1611(w)
1582(w)
–
466(w)
370(w)a
c
R.b.: ring bending; F: furan; S: thiophene; s: strong; b: broad; w: weak; sh: shoulder; m: medium; *: coordinated water; a: ꢀ(M Cl); b: monodentate acetate ꢀ(COO)−
monodentate nitrate ꢀ(NO3)−
; :
.
by 28 cm−1 relative to that of free ligand. Also, the band due to
ꢀ(NH) is perturbed upon complexation. This indicates that the
ligand in these complexes reacts as a bidentate molecule and coor-
dination occurs via the carbonyl oxygen atom and anilino nitrogen
atom.
The infrared spectra of metal complexes (4 and 12) reveal that
the disappearance of ꢀ(C O) band in free ligands HL1 and HL2 and
the formation of a new band at about 1605–1610, 1545–1595 cm−1
exhibited shifts to lower frequency, whereas the hetero-atoms,
oxygen or sulphur atom displayed shifts to higher frequency by
37–41 cm−1 upon complexation. According to this assumption, the
azomethine nitrogen atom and hetero-atoms become involved in
coordination to form complexes (4 and 12). In addition, the band
due to ꢀ(NH) (3118 cm−1) for HL1 ligand is absent in complex (4)
while, the ꢀ(NH) (3218 cm−1) for HL2 is unchanged upon complex-
ation (12). This indicates that the anilino NH group takes place in
coordination to form binuclear complex (4) and is not involved in
complex (12). The above discussion, along with elemental analy-
ses, suggests that the ligand HL1 reacts as enolic tetradentate with
are attributed to the ꢀ(C
N N C) and ꢀ(N C O), respectively.
This is in agreement with the deprotonated nature of lig-
ands [9,17,25]. The ꢀ(HC N) band of free ligands HL1 and HL2

100
S.M. Emam et al. / Spectrochimica Acta Part A 92 (2012) 96–104
Table 3
Magnetic moments ꢃeff (B.M.) and electronic spectral bands for metal complexes in solid state.
No.
Compound
ꢃeff (B.M.)a
d–d transitions (nm)
1
2
3
4
5
6
7
8
[Co(HL1)(OAc)2(H2O)2]·1.5H2O
[Co(HL1)2]Cl2·H2O
5.01
3.44
3.01
1.10
5.80
6.01
4.62
1.74
4.40
4.60
4.20
1.75
1.68
1.08
3.35
4.30
5.70
1.70
5.90
2.30
1.65
626(w), 584(w)
692(s), 668(s), 632(s).
628(w), 574(w), 526(s)
624(w), 588(w), 528(s)
529(w), 568(w)
594(w), 554(m), 532(m)
626(w), 604(w), 566(s)
746(w), 600(w), 564(s)
584(s), 538(s)
[Ni(HL1)Cl2(H2O)2]·2H2O
[Ni2(L1)(OAc)3(H2O)3]
[Mn((HL1)Cl2(H2O)2]
[Mn((HL1)(OAc)2(H2O)2]
[Fe(HL1)Cl3]
[Ru((HL1)Cl3(H2O)]
9
[Co(HL2)(OAc)2]·4H2O
10
11
12
13
14
15
16
17
18
19
20
21
[Co(HL2)2]Cl2·H2O
688(s), 658(s), 626(s), 604(w)
626(w), 566(w)
652(br), 580(w)
[Co(HL2)2(OH)2]·H2O
[Cu(L2)(OAc)(H2O)2]·H2O
[Cu(HL2)Cl2(H2O)2]·H2O
[Cu(HL2)(NO3)2]·0.5EtOH
[Ni(HL2)(OAc)2(H2O)2]
[Ni(HL2)Cl2]·7H2O
664(br), 586(w)
680(br), 584(m), 550(w)
766(w), 700(w), 625(w), 578(m)
875(w), 830(w),760(w), 690(w), 570(m)
600(w), 572(w), 542(m)
624(w), 552(w), 526(m)
600(w), 576(s), 560(m)
622, 592, 570, 532(m)
762(w), 600(w), 570(s)
[Mn(HL2)(OAc)2(H2O)2]
[Mn(HL2)Cl2(H2O)2]·1.5H2O
[Fe(HL2)Cl3]·2H2O
[Cr(HL2)2Cl2]Cl·EtOH
[Ru(HL2)Cl3]·0.5EtOH
w: weak; m: medium; s: strong; b: broad.
a
Per metal atom.
nickel acetate to form binuclear complex (4). However, the lig-
and HL2 reacts as enolic tridentate with copper acetate to form
mononuclear complex (12).
New bands are found in spectra of complexes in the regions
546–490, 492–410 and 366–415 cm−1 assigned to ꢀ(M–O), ꢀ(M–N)
and ꢀ(M–S), respectively [10,24]. The spectra of acetato com-
(Table 3) [28,29]. The low magnetic moment value 1.1 B.M. for com-
plex (4) is due to a super magnetic exchange interaction via bridging
of enolic oxygen atom, which binds two nickel(II) atoms forming
the binuclear complex. The spectrum of nickel(II) complex (16) and
the magnetic moment value 4.3 B.M. are compatible with tetrahe-
dral nickel complex. The spectrum displays multiple bands near 875
plexes show two bands near 1600–1575 and 1400–1325 cm−1
,
and 570 nm, assigned to the 3T1(F)→ A2(ꢀ2) and 3T1(F)→ T1(ꢀ3)
3
3
due to ꢀas(COO−) and ꢀs(COO−), respectively, suggesting that the
acetate ligand coordinates as a monodentate ligand [3]. The spec-
trum of complex [Cu(HL2)(NO3)2]·0.5EtOH (14) shows two bands at
1389 and 1300 cm−1, assigned to ꢀas(NO3−) and ꢀs(NO3−), respec-
transitions, respectively [30].
The spectra of copper(II) complexes (12 and 13) consist a broad,
weak band centered at 664–652 and 586–580 nm, and assigned to
2
2
2B1g→ B2g and 2B1→ Eg, indicating tetragonally distorted octahe-
dral structure [22,28]. The copper complex (14) shows a multiple
band near 550 nm which states a square planar geometry around
Cu(II) ion [6,25]. The magnetic moment value of complexes (12 and
13) is 1.68–1.73 B.M., corresponding to the spin value (1.73 B.M.),
indicating the monomeric nature [17]. The low magnetic moment
of the copper(II) complex (14) (1.08 B.M.), suggests the presence
of magnetic exchange interaction between adjacent Cu(II) atoms
[28,30].
−
tively, indicating that the NO3 group reacts as a monodentate
ligand [9,25]. The spectra of chloro-complexes display a new band
in the range 330–380 cm−1 assigned to ꢀ(M Cl) [26]. The spec-
tra of complexes which contain water molecules show a broad
band near 3480–3380 cm−1, assigned to ꢀ(OH) of crystallization
water involved in the complexes [2,27]. Moreover, the spectra of
complexes containing coordinated water molecules show addi-
tional two bands near 960 and 640 cm−1, owing to ꢄrock(H2O) and
ꢄwagg(H2O), respectively [1,25]. The appearance of the latter two
modes indicates coordinated water rather than hydrated water.
The manganese(II) complexes display three absorption bands in
624–592, 572–552 and 542–532 nm region, characteristic of octa-
4
hedral geometry. These bands are assigned to 6A1g→ T1g (4G) (ꢀ1),
4
4
6A1g→ Eg (4G) (ꢀ2) and 6A1g→ Eg (4D) (ꢀ3) transitions, respec-
tively [10,31]. The ꢃeff values (5.7–6.1 B.M.) for manganese(II)
complexes (5, 6 and 17) are compatible with high-spin octahedral
Mn(II) complexes [26]. Complex (18) has (ꢃeff = 1.7 B.M.), indicative
of low spin octahedral geometry for Mn(II) complex.
3.2.2. Electronic spectra and magnetic moments
The electronic spectral data of the metal complexes in nujol mull
and their room temperature magnetic moment values (ꢃeff B.M.)
per metal ion are given in Table 3.
The electronic spectra of cobalt(II) complexes (2, 9 and 10) reveal
(ꢀ3) band as a high intensity multiple bands, assigned to tetrahedral
arrangement around the cobalt(II) ion [28]. The magnetic moment
values (ꢃeff = 3.44–4.6 B.M.) provide further evidence for tetrahe-
dral geometry for cobalt(II) complexes [10,25], while the cobalt(II)
complexes (1 and 11) display the (ꢀ3) as a weak intensity broad
bands at 626 and 584–566 nm [27,28]. These bands, gathered with
(ꢃeff values = 4.2–5.01 B.M.), suggest spin free octahedral geometry
[19,27,29].
The electronic spectra of iron(III) complexes (7 and 19) show
absorption bands near 626–600 and 576–560 nm, assigned to the
4
4
6A1g→ T2g and 6A1g→ A1g (G) transitions in octahedral stereo-
chemistry [32]. The observed magnetic moment value of iron(III)
complex (19) is 5.9 B.M., indicating high spin octahedral of iron(III)
complexes [3,9]. The lower magnetic value 4.6 B.M. of complex (7)
is due to the presence of equilibrium between high and low spin
state [33].
The electronic spectrum of chromium(III) complex (20) displays
four bands at 622, 592, 570 and 532 nm. These bands are consistent
with octahedral stereochemistry [31]. The low ꢃeff value (2.3 B.M.)
of Cr(III) complex is attributed to existence of magnetic exchange
interaction between adjacent Cr(III) atoms.
The nickel(II) complexes (3, 4 and 15) display three bands
in range 766–700 (ꢀ1), 628–624 (ꢀ2) and 578–526 (ꢀ3) nm
3
3
3
attributable to 3A2g→ T2g, 3A2g→ T1g(F) and 3A2g→ T1g(p) tran-
sitions, respectively, characteristic of octahedral geometry [27].
The room temperature magnetic moment values are 1.1–3.35 B.M.

S.M. Emam et al. / Spectrochimica Acta Part A 92 (2012) 96–104
101
Table 4
ESR spectral parameter of copper(II) complexes.
2
Compound
12
aꢅ1
aꢅ2
g//
g
<g>
G
K//
K
K
˛
ˇ2
A//(G)
g///A// (cm−1
)
)
⊥
⊥
17,065
15,037
2.239
2.057
2.12
4.19
0.73
0.75
0.74
0.64
1.65
120.0
179.12
aꢅ2
gx
2.23
gy
2.09
gz
R
K//
K
K
˛
ˇ2
A//(G)
g///A// (cm−1
2
Compound
aꢅ1
⊥
14
–
–
2.03
0.43
–
–
–
–
–
–
–
a
Unit of ꢅ is cm−1
.
The ruthenium(III) complexes (8 and 21) gave three absorption
bands in the regions 762, 600 and 576–560 nm. These bands, in
connection with ꢃeff values (1.74–1.65 B.M.), indicate a low spin
octahedral geometry [3,26].
complexes [30,37]. The range reported for square planar com-
plexes is 105–135 cm−1 and for tetragonal distorted complexes
is >135–250 cm−1. The complex (12) has (g///A// = 179.12 cm−1),
which lies in the range reported for tetragonal distorted copper(II)
complexes [30,38]. The g-value of the copper complexes with a 2B1g
ground state can be related to k// and k components of the orbital
reduction factor (k) as follows [39,40]:
⊥
3.2.3. Electronic spin resonance spectral studies
The esr spectrum pattern of the solid copper(II) complex (12) at
room temperature exhibits an axial type symmetry (Table 4), where
(g// − 2.0023)ꢅ2
8ꢆo
(g⊥ − 2.0023)ꢅ1
2ꢆo
k/2/
=
,
k⊥2
=
,
g// > g > 2.0023, indicating d
copper(II) complexes [34]. The calculated <g > = (g// + 2g )/3 = 2.12,
ground state for tetragonal
2
2
⊥
(x −y
)
(k/2/ + 2k⊥2 )
⊥
k2
=
suggests the high covalence property of complex with distorted
symmetry [23]. In an axial symmetry, the g-values are related
by G = (g// − 2.003)/(g⊥ − 2.003) = 4.0, if G > 4, the exchange inter-
action between copper(II) centers in the solid state is negligible.
Whereas G < 4, a considerable exchange interaction occurs in the
solid state complexes. The G value of complex is 4.19, ruling out
the exchange interactions [10] and assigning the tetragonal dis-
torted geometry [35,36]. This result is in agreement with the
magnetic moment value (1.73 B.M.) for complex (12). The hyperfine
3
where ꢆo is the spin–orbit coupling of the free copper(II) ion
(ꢆo = −828 cm−1), ꢅ1 and ꢅ2 are the electronic transitions, 2B1g
→
2Eg and 2B1g
→
2B2g, respectively. The calculated values of k2 , k⊥2
//
and k2 (Table 4) exhibit the lower value of k than the unity (0.74),
due to covalent nature [30,40], which is in agreement with the
lower value of g//.
The fraction of the unpaired electron density on copper(II) ion,
coupling constants A// = 120G and A = 25G indicate the dynamic
in plane ꢇ-bond coefficients ˛2 was calculated by [23,41]:
⊥
tetragonal distortion for d(x
ground state [23]. Also g// = 2.23
2
)
2
−y
A//
3
7
corresponds to covalence character of metal–ligand bond [30,32].
2
˛
=
+ (g// − 2.0023) + (g⊥ − 2.0023) + 0.04
The (g///A//) values indicate the stereochemistry of the copper(II)
0.036
Table 5
TGA data for some metal complexes.
No.
Complex
Temperature
range (◦C)
Weight loss
Found/(Calcd.)
Assignment
Ts (◦C)
1
[Co(HL1)(OAc)2(H2O)2]·1.5H2O
32–159
159–218
218–441
441–700
700
49–127
127–190
190–267
267
147–181
181–241
241–315.75
315.75–600
600
5.10 (5.43)
6.95 (7.24)
23.81 (23.73)
46.00 (46.11)
16.65 (16.30)
4.9 (3.9)
3.6 (3.9)
24.0 (23.3)
– –
7.09 (6.89)
4.87 (5.17)
22.27 (22.59)
34.88 (34.14)
30.89 (31.19)
Loss 1.5 molecules of hydrated water(a) s.d.
Loss two molecules of coordinated water(d)
Loss two molecules of coordinated acetate(d)
Decomposed of organic ligand(d)
159
CoO + C(f)
3
9
[Ni(HL1)Cl2(H2O)2]·2H2O
[Co(HL2)(OAc)2]·4H2O
Loss one molecule of hydrated water(a)
Loss second molecule of hydrated water(a) s.d.
Loss two molecules of coordinated water and two chloride ions(d)
Decomposed of organic ligand(d)
190
241
Loss two molecules of hydrated water(a)
Loss one and half molecules of hydrated water(a) s.d.
Loss two molecules of coordinated acetate(d)
Decomposed of organic ligand and loss 0.5H2O(d)
CoS + 6C(f)
12
13
16
[CuL2(OAc)(H2O)2]·H2O
[Cu(HL2)Cl2(H2O)2]·H2O
[Ni(HL2)Cl2]·7H2O
50–160
160–191
191–241
241–500
500
112–161
161–200
200–300
300–790
790–800
35–85
4.5 (4.1)
8.2 (8.0)
13.69 (13.15)
48.0 (48.4)
26.9 (26.62)
4.0 (3.9)
Loss one molecule of hydrated water(a) s.d.
Loss two molecules of coordinated water(d)
Loss of coordinated acetate(d)
160
161
148
Decomposed of organic ligand(d)
CuS + 2C(f)
Loss one molecule of hydrated water(a) s.d.
Loss two molecules of coordinated water(d)
Loss two coordinated chloride ions(d)
Decomposed of organic ligand(d)
CuS + 3C(f)
8.2 (7.8)
15.8 (15.4)
44.2 (44.4)
27.9 (28.5)
16.8 (17.01)
7.3 (6.81)
13.35 (13.43)
48.46 (48.64)
14.05 14.08
Loss five molecules of hydrated water(a)
Loss of the remaining two molecules of hydrated water(a) s.d.
Loss two coordinated chloride ions(d)
Decomposed of organic ligand(d)
NiO(f)
85–148
150–258
255–650
650
s.d.: start of decomposition; (a): dehydration; (d): decomposition; (f): final product; Ts: thermal stability.

102
S.M. Emam et al. / Spectrochimica Acta Part A 92 (2012) 96–104
Table 6
Minimal inhibitory concentrations (MICs: mg/mL) of metal complexes of HL2 ligand.
Compound
Gram-negative bacteria
Gram-positive bacteria
Fungs
Escherichia coli
Klebsiella pneumonia
Bacillus cereus
Staphylococcus aureus
Candida albicans
(10)
(12)
(14)
(15)
25.0
ND
20.0
ND
ND
30.0
45.0
30.0
ND
ND
ND
25.0
ND
ND
ND
ND
ND
15.0
15.0
ND
(16)
(19)
Ampicillin
Clorimazole
12.0
10.0
0.025
–
10.0
10.0
0.050
–
12.0
15.0
0.0125
–
50.0
10.0
0.0125
–
15.0
10.0
–
0.025
ND: non detected.
R
R
Ro
H
NH
C
C
NH
Cl
Ru
OH2
Y
M
Y
H
O
N
.nH2O.mEtOH
O
Z
N
Z
Cl
Cl
RX
Complex (8)
Complex
(1)
M
X
Y
Z
n
1.5
1
m
-
Co(III)
O
S
S
S
H2O
H2O
-
OAc
Cl
R
NH
(13) Cu(II)
(14) Cu(II)
(18) Mn(II)
-
Rs
NO3
Cl
-
0.5
-
O
N
.Cl2.H2O
Co/2
H2O
1.5
H
Complex (10)
R
C
N
CH
C
O
N
H
OH2
OAc
Ni
OH2
O
N
S
H
NH
N
.H2O
R
Cu
Ni
O
H2O
OAc
O
H2O
AcO
OH2
O
CH3
Complex (12)
Complex (4)
Rs
H
N
O
CH
O
C
N
.Cl2.H2O
.4H2O
AcO
OH2
OAc
N
Co
/2
H2C
Ni
N
OH2
Complex(2)
H
R
Complex(15)
Scheme 1.

S.M. Emam et al. / Spectrochimica Acta Part A 92 (2012) 96–104
103
R
NH
Cl
M
H
O
N
HC
X
.nH2O.mEtOH
.nH2O
R
Y
Cl
N
M
X
C
Cl
Z
N
H
O
Y
Z
Complex
M
X
Y
Z
n
-
Complex
(7)
M
X
n
m
-
(6)
(9)
Mn(II)
Co(II)
O
S
S
S
H2O
-
OAc
OAc
OAc
Cl
Fe(III)
O
-
1
-
4
-
(19) Fe(III)
(21) Ru(III)
S
-
S
0.5
(17) Mn(II)
H2O
H2O
(22) Zr(IV)O
5
R
C
R
NH
NH
H
Cl
Ni
Cl
Ni
H
O
N
O
N
.7H2O
.7H2O
Cl
Cl
S
S
Complex (16)
H
N
Rs
H2C
C
O
R
Cl
N
M/2
H
HN
H2O
O
.nH2O
X
.nH2O.mEtOH.zCl
H
M
OH2
N
X
H
Cl
H
R
Complex
(11)
M
X
n
1
-
m
-
z
-
Complex
(3)
M
n
2
-
Co(II) OH
Cr(III) Cl
Ni(II)
(20)
1
1
(5)
Mn(II)
Rs
Rs: Furan ring
Rs: Thiophene ring
H
N
O
CH
C
N
S
O
.4H2O
Cl
OH
Cl
H2C
Hf
CH3
H2
N
OH
C
R
:
R
N
H
R:
H
R
Complex(23)
Scheme 1. (Continued )

104
S.M. Emam et al. / Spectrochimica Acta Part A 92 (2012) 96–104
The calculated value, ˛2 = 0.61, suggests the covalent character
[30,42].
The in-plane and out-plane ␲-bonding coefficients (ˇ1 and ˇ2)
References
[1] S.M. Emam, F.A. El-Saied, S.A. AbouEl-Enein, H.A. El-Shater, Spectrochim. Acta
Part A 72 (2009) 291–297.
are dependent upon the values of ꢅ1 and ꢅ2 as in these expressions
[39,40]:
[2] A.R. Yaul, V.V. Dhande, A.S. Aswar, Rev. Roum. Chim. 55 (2010) 537–542.
[3] A.S. El-Tabl, F.A. El-Saied, W. Plass, A.N. Al-Hakimi, Spectrochim. Acta Part A 71
(2008) 90–99.
[4] Y. Li, Z.-Y. Yang, M.-F. Wang, J. Fluoresc. 20 (2010) 891–905.
[5] S.B. Desai, P.B. Desai, K.R. Desai, Heterocycl. Commun. 7 (2001) 83–90.
[6] M.S. Niasari, A. Amiri, Appl. Catal. A 290 (2005) 46–53.
[7] M.C.R. Arguelles, M.B. Ferrari, F. Bisceglie, C. Plizzi, G. Pelosi, S. Pinelli, M. Sassi,
J. Inorg. Biochem. 98 (2004) 313–321.
[8] P. Yogeeswari, N. Menon, A. Semwal, M. Arjun, D. Sriram, Eur. J. Med. Chem. 46
(2011) 2964–2970.
[9] S.A. AbouEl-Enein, F.A. El-Saied, T.I. Kasher, A.H. El-Wardany, Spectrochim. Acta
Part A 67 (2007) 737–743.
[10] F.A. El-Saied, S.A. AbouEl-Enein, S.M. Emam, H.A. El-Shater, Polish J. Chem. 83
(2009) 1871–1883.
[11] T.M. Aminabhavi, N.S. Biradar, S.B. Patil, D.E. Hoffman, V.N. Biradar, Inorg. Chim.
Acta 135 (1987) 139–143.
[12] A.W. Bauer, M.D.K. Kirby, J.C. Sherris, M.D. Truck, Am. J. Clin. Pathol. 45 (1966)
493–496.
[13] P.S. Negi, G.K. Jayaprakasha, B.S. Jena, LWT—Food Sci. Technol. 41 (2008)
1857–1861.
(g// − 2.0023)ꢅ2
=
8ꢆo
(g⊥ − 2.0023)ꢅ1
2ꢆo
˛2ˇ2
=
,
˛2ˇ12
The value of ˇ12 = 0.84 indicates a moderate degree of covalency of
the in-plane ␲-bonding; while ˇ2 = 1.65, assigns ionic character of
the out-of-plane ␲-bonding [3,43].
The approximate orbital population for the d orbital was esti-
mated by [44,45]:
ꢀ
ꢁ
(A// + 2A )
⊥
7
4
Aiso
=
,
A// = Aiso − 2B 1 +
ꢈg//,
3
2B
ꢈg// = g// − 2.0023, ap2,d
=
2Bo
where 2Bo is the calculated dipolar coupling for unit occupancy
of the d orbital. The parallel component of the dipolar coupling
(2B = −272G) is negative and the orbital population is 81%, indicat-
[14] T.M. Hansen, Y.-G. Gu, T.M. Rehm, P.J. Dandliker, L.E. Chovan, M.H. Bui, A.M.
Nilius, B.A. Beutel, Bioorg. Med. Chem. Lett. 15 (2005) 2716–2719.
[15] J. Lewis, R.G. Wilkins, Modern Coordination Chemistry, Interscience, New York,
1960, p. 403.
[16] L.S. Vojinovic, V.M. Leovac, S.B. Novakovic, G.A. Bogdanovic, J.J. Csanadi, V.I.
Cesljevic, Inorg. Chem. Commun. 7 (2004) 1264–1268.
[17] R. Gup, B. Kirkan, Spectrochim. Acta Part A 62 (2005) 1188–1195.
[18] A.S. El-Tabl, Bull. Korean Chem. Soc. 25 (2004) 1757–1763.
[19] H.F. Abd El-halim, M.M. Omar, G.G. Mohamed, Spectrochim. Acta Part A 78
(2011) 36–44.
ing that the ground state is d(x
[3,30].
2
)
2
−y
The spectrum of copper complex (14) shows non-axial parame-
ter (Table 4) where gx = 2.23, gy = 2.09 and gz = 2.03. The geometric
parameter, R = (gy − gz)/((gx − gy) = 0.43, means that
a d(x
2
2
−y
)
ground state prevails [25,46]. The gy value <2.3 was reported for
[20] N. Al-Awadi, N.M. Shuaib, A. El-Dissouky, Spectrochim. Acta Part A 65 (2006)
36–43.
covalent bond character [25,47,48].
[21] D.C. Sulikowska, A. Czylkowska, J. Therm. Anal. Calorim. 76 (2004) 543–555.
[22] A.S. El-Tabl, S. AbouEl-Enein, J. Coord. Chem. 57 (2004) 281–294.
[23] M.S. Masoud, S.A. AbouEl-Enein, M.E. Ayad, A.S. Goher, Spectrochim. Acta Part
A 60 (2004) 77–87.
[24] M.S. Refat, I.M. El-Deen, H.K. Ibrahim, S. El-Ghool, Spectrochim. Acta Part A 65
(2006) 1208–1220.
[25] H.M. El-Tabl, F.A. El-Saied, M.I. Ayad, Synth. React. Inorg. Met. Org. Chem. 32
(2002) 1189–1203.
[26] M.F.R. Fouda, M.M. Abd El-Zaher, M.M.E. Shakdofa, F.A. El-Saied, M.I. Ayad, A.S.
El-Tabl, Trans. Met. Chem. 33 (2008) 219–228.
[27] P.K. Singh, D.N. Kumar, Spectrochim. Acta Part A 64 (2006) 853–858.
[28] S.A. AbouEl-Enein, J. Therm. Anal. Calorim. 91 (2008) 929–936.
[29] S.A. AbouEl-Enein, F.A. El-Saied, S.M. Emam, M.A. El-Salamony, Spectrochim.
Acta Part A 71 (2008) 421–429.
[30] H.A. El-Boraey, S.M. Emam, D.A. Tolan, A.M. El-Nahas, Spectrochim. Acta Part A
78 (2011) 360–370.
[31] R. Sharma, S.K. Agarwal, S. Rawat, M. Nagar, Trans. Met. Chem. 31 (2006)
201–206.
[32] D. Kumar, P.K. Gupta, A. Syamal, J. Chem. Sci. 117 (2005) 247–253.
[33] A.M. Donia, H.A. El-Boraey, M.F. El-Samalehy, J. Therm. Anal. Calorim. 73 (2003)
987–1000.
[34] O.I. Singh, M. Damayanti, N.R. Singh, R.K.H. Singh, M. Mohapatra, R.M. Kadam,
Polyhedron 24 (2005) 909–916.
[35] B.J. Hathaway, D.E. Billing, Coord. Chem. Rev. 5 (1970) 143–207.
[36] M.S. Masoud, S.A. AbouEl-Enein, I.M. Abed, A.E. Ali, J. Coord. Chem. 55 (2002)
153–178.
[37] D.E. Nickless, M.J. Power, F.N. Urbach, Inorg. Chem. 22 (1983) 3210–3217.
[38] A.S. El-Tabl, F.A. El-Saied, A.N. Al-Hakim, J. Coord. Chem. 61 (2008) 2380–2401.
[39] Z.L. Lu, C.Y. Duan, Y.P. Tian, X.Z. You, Inorg. Chem. 35 (1996) 2253–2258.
[40] E.I. Solomon, M.J. Baldwin, M.D. Lowery, Chem. Rev. 92 (1992) 521–542.
[41] R.P. John, A. Speekanth, M.R.P. Kurup, A. Usman, A.R. Ibrahim, H.K. Fun, Spec-
trochim. Acta Part A 59 (2003) 1349–1358.
[42] A.S. El-Tabl, F.A. El-Saied, A.N. Al-Hakim, Trans. Met. Chem. 32 (2007) 689–701.
[43] S. Chandra, D. Jain, A.K. Sharma, Spectrochim. Acta Part A 71 (2009) 1712–1719.
[44] M.C.R. Symon, Chemical and Biochemical Aspect of Electron Spin Resonance
Spectroscopy, Van Nostrand Resinhold Company Ltd., Molly Millors Lane, Wok-
inghold, Berkshire, England, 1978.
3.2.4. Thermal studies
The infrared spectra and elemental analyses show the presence
of water molecules in the chemical structures of metal complexes.
Therefore, the thermogravimetric analysis TGA was undertaken for
some of the investigated metal complexes. The TGA data and their
assignments are summarized in (Table 5). The TGA data show that
the investigated complexes (1, 3, 9, 12, 13 and 16) display a weight
loss within the temperature range 32–241 ◦C assignable to the loss
of water of hydration [49,50]. The TGA curves also show the loss of
coordinated water molecules in complexes (1, 3, 12 and 13) within
the temperature range 159–267 ◦C [51,52]. The acetato complexes
(1, 9 and 12) also reveal the loss of coordinated acetate group within
the temperature range 218–414 ◦C [1]. The three complexes (3, 13
and 16) show a weight loss within temperature range 150–300 ◦C,
corresponding to the loss of coordinated chloride ions [28,29]. The
decomposition of the organic ligand takes place within tempera-
ture range 241–840 ◦C [19,53]. The thermal decomposition process
ended with the formation of metal oxide from complexes (1 and
16), or metal sulphide from complexes (9, 12 and 13) [19,28]. The
TGA data of complexes (3, 9 and 16) point out to the loss of hydrated
water molecules at two ranges of temperature (Table 5), indicating
that not all molecules of hydrated water bind similarly within the
solid crystal [30,52].
The obtained data are consistent with the proposed chemical
structure of complexes as shown in Scheme 1.
3.2.5. Antibacterial activity
Minimum inhibitory concentrations (MICs) of metal complexes
of HL2 are given in Table 6. All tested metal complexes (10,
12, 14–16 and 19) are very weakly active against all tested
microorganisms, E. coli and K. pneumonia (as gram negative bac-
teria) and B. cereus and S. aureus (as gram positive bacteria) and
C. albicans (as fungs). The MIC values of these compounds are
of 10000.0–50000.0 ␮g/mL when compared with the reference
antibacterial agent, ampicillin (12.5–50.0 ␮g/mL) and antifungal
agent; clorimazole (25.0 ␮g/mL) but complex (15) lacks any vir-
tually microbial activity towards all tested microorganisms.
[45] M.I. Ayad, A.S. El-Tabl, Polish J. Chem. 73 (1999) 263–269.
[46] C. Natarajan, P. Shanthi, P.A. Thappan, R. Murvgesan, Trans. Met. Chem. 17
(1992) 39–45.
[47] D. Kivelson, R. Neiman, J. Chem. Phys. 35 (1961) 149–155.
[48] B. Kebede, N. Retta, V.J.T. Raju, Y. Chebude, Trans. Met. Chem. 31 (2006) 19–26.
[49] M.S. Niasari, F. Davar, K. Saberyan, Polyhedron 29 (2010) 2149–2156.
[50] M.S. Masoud, A. El-Merghany, A.M. Ramadan, M.Y. Abd El-Kaway, J. Therm.
Anal. Calorim. 101 (2010) 839–847.
[51] M.S. Niasari, N. Mir, F. Davar, Polyhedron 28 (2009) 1111–1114.
[52] M.S. Masoud, S.A. AbouEl-Enein, A.M. Ramadan, A.S. Goher, J. Anal. Appl. Pyrol.
81 (2008) 45–51.
[53] M.S. Niasari, Polyhedron 28 (2009) 2321–2328.