Two novel macroacyclic schiff bases containing bis-N2O2 donor set and their binuclear complexes: synthesis, spectroscopic and magnetic properties

Article abstract of DOI:10.1016/j.molstruc.2009.01.037

Herein, we report two novel macroacyclic Schiff bases derived from tetranaphthaldehyde derivative compound and their binuclear Mn(II), Ni(II), Cu(II) and Zn(II) complexes. The structures of the compounds have been proposed by elemental analyses, spectrosc

Full text of DOI:10.1016/j.molstruc.2009.01.037

Journal of Molecular Structure 922 (2009) 39–45
Contents lists available at ScienceDirect
Journal of Molecular Structure
journal homepage: www.elsevier.com/locate/molstruc
Two novel macroacyclic schiff bases containing bis-N2O2 donor set and their
binuclear complexes: synthesis, spectroscopic and magnetic properties
b
c
Kaan Karaoglu a, Talat Baran a, Kerim Serbest a, , Mustafa Er , Ismail Degirmencioglu
*
a Department of Chemistry, Rize University, Faculty of Art and Science, 53100 Rize, Turkey
b Department of Chemistry, Karabuk University, Faculty of Art and Science, 78050 Karabuk, Turkey
c Department of Chemistry, Karadeniz Technical University, Faculty of Art and Science, 61080 Trabzon, Turkey
a r t i c l e i n f o
a b s t r a c t
Article history:
Herein, we report two novel macroacyclic Schiff bases derived from tetranaphthaldehyde derivative com-
pound and their binuclear Mn(II), Ni(II), Cu(II) and Zn(II) complexes. The structures of the compounds
have been proposed by elemental analyses, spectroscopic data i.e. IR, 1H and 13C NMR, UV–Vis, electro-
spray ionisation mass spectra, molar conductivities and magnetic susceptibility measurements. The stoi-
chiometries of the complexes derived from mass and elemental analysis correspond to the general
formula [M2L(ClO4)n](ClO4)4ꢀn, (where M is Mn(II), Ni(II), Cu(II), Zn(II) and L represents the Schiff base
ligands).
Received 22 October 2008
Received in revised form 13 January 2009
Accepted 20 January 2009
Available online 23 February 2009
Keywords:
Schiff bases
Transition metals
N2O2 donor set
NMR
Ó 2009 Elsevier B.V. All rights reserved.
Mass spectra
1. Introduction
In view of these finding and in continuation to our previous
work on the Schiff bases [26], this work has devoted with the
Schiff bases can form coordinate bond with the transition metal
atom ion via nitrogen atom of C@N– double bond, and with an
ortho-position oxygen(O) or sulfur(S) atom which have a lonely
pair of electrons. Schiff base complexes have specific activities of
pharmacology and physiology [1a,b]. They have wide applications
in various fields such as illness treatment, biochemical reaction
and biological regulator and have been studied for their interesting
and important properties, [1c,2–5]. Therefore, people pay a great
interest in their synthesis, structure, biological activity and appli-
cation of this kind of complexes [6–8].
aim to synthesize some homo–dinuclear Mn(II), Ni(II), Cu(II) and
Zn(II) complexes with two novel macroacyclic Schiff bases ligands
(Fig. 1), and to examine their physical properties involving spectral
behaviors by IR, 1H and 13C NMR, UV–Vis, electrospray ionisation
mass spectra, molar conductivities and magnetic moment data. A
detailed assignment of the spectra and the electrochemical behav-
ior were proposed.
2. Experimental
2-Hydroxy Schiff base ligands and their complexes derived from
the reaction of salicylaldehyde and 2-hydroxy-1-naphthaldehyde
derivatives with amines have been extensively studied [9–14]
and a number of them were used as models for biological systems
[15–19]. In addition, a large number of dinuclear complexes have
been synthesized and structurally characterized in attempts to
mimic the active sites of metallo-enzymes [20–22].
There have been numerous transition metal complexes contain-
ing N2S2 or N2O2 donor set [23,24] but only a few examples of com-
plexes containing a bis-N2O2 donor set have been reported in the
literature [25].
2.1. Physical measurements
Melting points (m.p.) were determined on a Barnstead/Electro-
thermal 9100 apparatus in open capillary tubes. IR spectra were
recorded on a Perkin Elmer Spectrum 100 FTIR spectrophotometer
as KBr pellets. 1H and 13C NMR. spectra were recorded on a Varian
Gemini 200 and Varian Mercury 400 spectrometer using chloro-
form-d1/DMSO-d6 solvents at Department of Chemistry, Karadeniz
Technical University, Trabzon and Ataturk University, Erzurum,
respectively. Chemical shifts (d) are reported in part per million
(ppm) relative to an internal standard of Me4Si. A Shimadzu 1601-
PC UV/Vis spectrophotometer was used to record the electronic
spectra. Room temperature (296 K) solid state magnetic susceptibil-
ities were measured by using a Sherwood Scientific magnetic sus-
ceptibility balance and MnCl2.6H2O was used as the standard.
* Corresponding author. Fax: +904642235376.
E-mail address: kerimserbest@yahoo.com (K. Serbest).
0022-2860/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.molstruc.2009.01.037

40
K. Karaoglu et al. / Journal of Molecular Structure 922 (2009) 39–45
8
7
6
5
9
4
10
15
16
11
3
12
2
17
O
O
N
1
N
14
13
8
7
6
5
9
N
N
O
O
4
10
11
3
12
2
NH2
O
O
OHC
i)
1
CHO
CHO
13
2, L1
8
CH3NH2
7
6
OHC
ii)
O
O
5
9
4
10
11
3
1
12
2
1
O
O
H3C
N
N
CH3
14
13
H3C
N
N
CH3
O
O
7, L2
Fig. 1. Synthesis pathway for ligands synthesis.
Elemental analyses were determined on a LECO CHNSO-932 auto
elemental analyses apparatus. Metal containing of the complexes
were determined by atomic absorption (Unicam 929) spectral tech-
niques using standard flames [27] and electrospray ionisation mass
spectrometry (ESI-MS) was performed on a VG 7070 spectrometer at
Department of Chemistry, Karadeniz Technical University, Trabzon,
Turkey. Solution electrical conductivities were measured at r.t. with
approximately 10ꢀ3 M DMF solutions, with a Hanna EC 215 conduc-
tivity meter by using 0.01 M KCl water solution as calibrant.
2.2. Materials
2-Hydroxy-1-naphthaldehyde, 2,3-dimethyl-1,3-butadiene
obtained from Fluka. The perchlorate salts of Mn(II), Ni(II),
Zn(II), Cu(II), bromine, aniline and methyl amine were pur-
chased from Merck. 2,20-[2,3-Bis(1-formyl-2-naphthyloxymeth-
yl)-but-2-ene-1,4-diyldioxy]bis(naphthalene-1-carbaldehyde) were
synthesized according to the procedure [28]. Organic solvents were
reagent grade chemicals.
Table 1
Analytical and physical data of Schiff bases and their complexes.
Compound
Color
Yield (%)
M.p. (°C)
[M+]
leff per metal
Kf
Found (Calcd.) (%)
ion at 296 K (BM)
C
H
N
M
–
L1, (2)
C74 H56 N4 O4
Yellow
83
56
66
67
65
62
34
58
52
62
183
190
122
188
201
184
200
249a
255a
215
1065b
–
–
82.9 (83.4)
5.2 (5.3)
5.4 (5.3)
[Mn2L1(ClO4)4], (3)
C74 H56 Cl4 Mn2 N4 O20
[Ni2L1(ClO4)4], (4)
C74 H56 Cl4 N4 Ni2 O20
[Cu2L1(ClO4)4], (5)
C74 H56 Cl4 Cu2 N4 O20
[Zn2L1(ClO4)4], (6)
C74 H56 Cl4 N4 O20 Zn2
L2, (7)
Brown
1572.26b
1582.50c
1590.14b
1596.74d
817.42b
1324.68b
1334.18c
1179.4e
1146.5f
5,27
10
56. 7 (56.5)
55.9 (56.2)
56.3 (55.9)
56.1 (55.8)
80.0 (79.4)
48.4 (49.0)
49.0 (48.7)
47.9 (48.3)
48.1 (48.2)
3.8 (3.6)
3.6 (3.6)
3. 7 (3.6)
3.6 (3.5)
6.0 (5.9)
3.8 (3.6)
3.7 (3.6)
3.4 (3.6)
3.7 (3.6)
3.5 (3.6)
3.4 (3.6)
3.7 (3.5)
3.8 (3.5)
6.9 (6.9)
4.4 (4.2)
4.0 (4.2)
4.1 (4.2)
4.2 (4.2)
7.3 (7.0)
7.2 (7.4)
7.9 (8.0)
8.1 (8.2)
–
Brown
2,45
20
63
2
Dark green
Light yellow
Light yellow
Light brown
Light green
Green
1,88
Diamagnetic
–
–
C54 H48 N4 O4
[Mn2L2(ClO4)4], (8)
C54 H48 Cl4 Mn2 N4 O20
[Ni2L2(ClO4)4], (9)
C54 H48 Cl4 N4 Ni2 O20
[Cu2L2(ClO4)2](ClO4)2, (10)
C54 H48 Cl4 Cu2 N4 O20
[Zn2L2(ClO4)2](ClO4)2, (11)
C54 H48 Cl4 N4 Zn2 O20
3,79
42
9
8.2 (8.3)
9.0 (8.8)
9.8 (9.5)
9.9 (9.7)
2,96
1,90
120
172
Light yellow
Diamagnetic
a
Decomposition.
b
[M]+.
c
[M+2]+.
d
[M+3)]+.
e
[M+2H2OA2ClO4+1]+.
f
[M-2ClO4+1]+. Molar conductivities were measured in DMF solvent with concentration ꢁ 10ꢀ3 M. Values are in (
X
ꢀ1 molꢀ1 cm2).

K. Karaoglu et al. / Journal of Molecular Structure 922 (2009) 39–45
41
Caution! perchlorates and perchlorate salts of metal complexes
with organic ligands are potentially explosive. Only a small
amount of material should be prepared and it should be handled
with care.
oxy]bis(naphthalene-1-carbaldehyde), (1) (2 g, 2,6 mmol) with ani-
line (10,4 mmol; 1.05 cm3) for 60 h, THF used as solvent. Reaction
was monitored by TLC using chloroform–ethanol (40:1). Upon cool-
ing, solvent was removed by rotary. Obtained yellow product was
refluxed in ethanol 1 h, then filtered off and washed with warm eth-
anol several times, dried in the oven; M.p. 148 °C, 83% yield.
2.3. Synthesis of ligands
2.3.1. Synthesisofphenyl{(1E)-[2-({4-({1-[(E)-(phenylimino)methyl]-2-
naphthyl}oxy)-2,3-bis[({1-[(E)-(phenylimino)methyl]-2-naphthyl}oxy)
methyl]but-2-en-1-yl}oxy)-1-naphthyl]methylene}amine, L1, (2)
The ligand was prepared by refluxing equimolar amounts of the
2,2’-[2,3-Bis(1-formyl-2-naphthyloxymethyl)-but-2-ene-1,4-diyldi-
2.3.2. Synthesis of methyl{(1E)-[2-({4-({1-[(E)-(methylimino)methyl]-
2-naphthyl}oxy)-2,3-bis[({1-[(E)-(methylimino)methyl]-2-naphthyl}
oxy)methyl]but-2-en-1-yl}oxy)-1-naphthyl]methylene}amine, L2, (3)
The ligand was prepared by stirring of the 2,2’-[2,3-Bis(1-for-
myl-2-naphthyloxymethyl)-but-2-ene-1,4-diyldioxy]bis(naphtha-
(ClO4)x
M
Mn(II)
Ni(II)
Cu(II)
Zn(II)
A
ClO4
ClO4
ClO4
ClO4
ClO4
ClO4
ClO4
ClO4
B
ClO4
ClO4
ClO4
ClO4
x
-
-
-
-
O
B
M
A
(3)
(4)
(5)
(6)
R
N
-
-
-
R:Phenyl
R:Methyl
O
-
-
A
M
B
R
N
N
R
O
-
-
-
R
N
-
-
-
Mn(II)
Ni(II)
Cu(II)
Zn(II)
ClO4
ClO4
-
-
-
-
2
(8)
(9)
(10)
(11)
O
-
-
-
2
Fig. 2. Proposed structure of the homo–dinuclear complexes.
Table 2
Characteristic IR bands of the Schiff bases and their metal complexes (in cmꢀ1).
Compound
m
(C@O)
m
(C@C)
m
(C@N)
m
(CAO)
m
(ClO4)ꢀ
Mono substitute phenyl
mM–O
mM–N
Tetraaldehyde (1)
L1, (2)
1673 s
1619 m, 1591 m
1624 m, 1586 s
1622 m, 1588
–
1238, 1208
1239 s, 1208 s
1236 s, 1211 s
1239
1239 s
1239 s
1211 s, 1234 s
1239 s, 1230
1239 s, 1231 s
1238 s
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
1608 m
1673 s
1674 s
1674 s
1674 s
1639 m
1672 s
1674 s
1671
694 m, 766 m
694 w, 749 m
694 m, 748 s
709 w, 751 m
[Mn2L1(ClO4)4], (3)
[Ni2L1(ClO4)4], (4)
[Cu2L1(ClO4)4], (5)
[Zn2L1(ClO4)4], (6)
L2, (7)
1069 brs, 621 w
1050,1075, 1118 m, 622 w
1089, 1102, 1121 brm, 621w
1088 m
574
571 w
570 w
570 w
–
570
570
567
–
506
507
501
506
–
520
504
503
–
1622 m, 1587 s
1618 m, 1590 s
1619 m, 1590 s
1615 m, 1588 m
1619 m, 1519 s
1619 s, 1591 s
1619 s, 1590 s
1620 m, 1590 m
708 w, 752 m
–
–
–
–
–
–
[Mn2L2(ClO4)4], (8)
[Ni2L2(ClO4)4], (9)
[Cu2L2(ClO4)2](ClO4)2, (10)
[Zn2L2(ClO4)2](ClO4)2, (11)
1093 brs, 623 m
1067 brm, 627 m
1086 brs, 624 s
1089, 1105, 1147 brs, 625 s
1663 s
1206 m,1238 s
s, sharp; m, medium; br, broad; w, weak.
Table 3
1H and 13C NMR spectral data of the Schiff bases in CDCl3.
1H data for L1
13C data for L1
1H data for L2
13C data for L2
5.05 s. (AOCH2ꢀ, 8H),
C-1
C-2
C-3
C-4
C-5
C-6
C-7
C-8
135.484
3.407–3.404 s. (CH3ꢀ, 12H),
5.115 s. (AOCH2-, 8H),
C-1
C-2
C-3
C-4
C-5
C-6
C-7
C-8
136.069
66.983
7.212–6.994 m. (Ar, 24H)
7.442, 7.404, 7.368 t. (Ar, 4H)
7.716, 7.523 m. (Ar, 12H)
9.072 s. (AHC@N, 4H)
66.627
157.584
118.156
133.761
129.543
128.549
124.673
125.659
125.826
131.857
113.550
157.637
152.766
120.758
129.050
128.299
7.278* (Ar, 4H)
156.449
119.128
132.289
129.853
128.312
124.714
125.837
128.259
132.547
114.187
159.674
49.761
7.409, 7.390, 7.371 t (Ar, 4H)
7.539, 7.521, 7.501 t (Ar, 4H)
7.754, 7.734 d (Ar, 4H)
7.809, 7.786 d (Ar, 4H, J = 9.16)
8.877 s. (AHC@N, 4H,)
9.327–9.286 d. (Ar, 4H)
C-9
9.004, 8.982 d. (Ar, 4H, J = 8.8)
C-9
C-10
C-11
C-12
C-13
C-14
15
C-10
C-11
C-12
C-13
C-14
C-16
C-17
*
The signal collides with signal of solvent proton and is probable a doublet.

42
K. Karaoglu et al. / Journal of Molecular Structure 922 (2009) 39–45
lene-1-carbaldehyde), (1) (2 g, 2,6 mmol) with excessive amount of
methyl amine solution (5 cm3, 41%) for a week at room tempera-
ture. Reaction was monitored by TLC using chloroform–ethanol
(40:1). Obtained solid product was washed with water, cold etha-
nol and diethyl ether several times, dried in the oven; M.p. 184 °C,
62% yield.
reflux and the mixture stirred for overnight at room temperature.
After the reaction was complete, the solvent was removed from the
reaction mixture to 10 mL volume in vacuo. 50 mL of distilled
water:ethanol (1:1) was poured into the reaction mixture with vigor-
ous stirring and precipitate was produced. The solid metal complexes
having 2:1 metal:ligand ratio were collected by filtration, washed
with water, ethyl alcohol and diethyl ether, respectively, and dried
over silica gel in vacuo.
2.4. Synthesis of metal complexes [M2L1(ClO4)n](ClO4)4-n
[M2L2(ClO4)n](ClO4)4-n
,
3. Results and discussion
ThemetalcomplexesoftheSchiffbaseswerepreparedbytheaddi-
tion of hot solution (40 °C) of the metal perchlarate (0.4 mmol) [Cu
(ClO4)2.6H2O, Ni(ClO4)2.6H2O, Zn(ClO4)2.6H2O or Mn(ClO4)2.6H2O]
in 10 mL ethanol to the hot solution (40 °C) of Schiff base (0.2 mmol)
in CH2Cl2 (30 mL). The resulting mixture was stirred for 6 h under
Analytical and physical data of Schiff bases and their complexes
are presented in Table 1. Macroacyclic Schiff bases were synthesized
by the condensation of 2,2’-[2,3-bis(1-formyl-2-naphtyloxymeth-
yl)but-2-ene-1,4-diyldioxy]bis(naphthalene-1-carbaldehyde), (1)
with aliphatic and aromatic primer amines in 1:4 molar ratio in
THF or CHCl3. The structures of Schiff bases were characterized by
using elemental analysis (C, H, N), 1H and 13C NMR, IR and mass spec-
tral data. In the proposed structure of the Schiff base ligands have
bis-N2O2 cores to form dinuclear metal complexes. The stoichiome-
triesof thecomplexesderivedfrommassandelementalanalysiscor-
respond to the general formula [M2L(ClO4)n](ClO4)4ꢀn, (where M is
Mn(II), Ni(II), Cu(II), Zn(II) and L is the Schiff base ligand). Proposed
structures of the homo–dinuclear complexes are shown in Fig. 2.
These propositions are also in accord with IR, UV–Vis data, magnetic
and molar conductivity measurements. The yellow-coloured Schiff
base (L1) is soluble in CHCl3, CH2Cl2, DMF, DMSO, pyridine but insol-
uble in water, ethanol, methanol. The light yellow-coloured Schiff
base (L2) is soluble in CHCl3, CH2Cl2, DMF, DMSO, pyridine but insol-
uble in water, ethanol, methanol and all the complexes are soluble in
DMF, DMSO and pyridine.
Table 4
1H NMR spectral data of the [Zn2L1(ClO4)4], (6) and [Zn2L2(ClO4)2](ClO4)2, (11).
1H data for 6 in CDCl3
1H data for 11 in DMSO-d6
10.833 s. .(AHC@N, 4H)
9.084, 9.105 d. (H10, 4H,
J = 8.4 Hz)
10.651 s. .(AHC@N, 2H) and 8.766 bs .(AHC@N, 2H)
9.098, 9.077 d. (H10, 2H, J = 8.4 Hz) and 8.978, 8.957 d.
(H10, 2H, J = 8.4 Hz)
8.034, 8.012 d. (H5, 4H,
J = 8.8 Hz)
8.238, 8.215 d. (H5, 2H, J = 9.2 Hz) 7.994, 7.971 d. (H5,
2H, J = 9.2 Hz)
7.755, 7.734 d. (H7, 4H,
J = 8.4 Hz)
7.915, 7.895 d. (H7, 2H, J = 8.0), 7.876, 7.856 d. (H7, 2H,
J = 8.0 Hz),
7.605, 7.602, 7.584 t. (H9, 7.745, 7.719 d. (H4, 2H, J = 10.4 Hz),
4H)
7.567, 7.563, 7.520 t. (H8, 7.645–7.565 m. (H8, 9, 4H), and 7.513–7.387 m. (H4, 8, 9
,
4H)
6H)
17
7.433–7.261 m. (H15,
8H)
,
5, 414 and 5.280 s. (H2, 8H)
7.177, 7.158, 7.137 t.
3.100* s. (H14, 6H)
(H16, 4H)
6.681, 6.700 d. (H4, 4H,
J = 7.6 Hz)
3.1. NMR spectra
5.219 s. (H2, 8H)
1H NMR spectra of Schiff base ligands were recorded in CDCl3
solution. These 1H NMR results are presented in Table 3 (see
*
The other singlet were hindered by H2O protons of solvent.
Fig. 3. The mass spectrum of [Zn2L1(ClO4)4].

K. Karaoglu et al. / Journal of Molecular Structure 922 (2009) 39–45
43
Fig. 1 for the numbering scheme). The singlet at d 10.67 ppm
belonging to tetraaldehyde protons of (1) disappears after the reac-
tion of the aniline and methylamine with the tetra aldehyde and a
new singlet at 9.072 ppm for L1, 8.877 ppm for L2 correspond to the
N@CH proton resonances. More detailed information about the
structure of Schiff bases (L1 and L2) is provided by its 13C NMR spec-
trum. In the spectrum of Schiff bases were observed disappearing
the carbonyl carbon signal of tetraaldehyde (1) at 190.72 ppm, a
new signal at 157.634 ppm for L1 and 156.974 ppm for L2 due to
imine carbon (C@N), a shift for the carbon of OAAr from 162.84
to 157.584 for L1 and 156.449 ppm for L2. These observations are
an evidence formation of Schiff bases.
to azomethine protons in the complexes appear at 10.833 as a sin-
glet for 6 and two singlets at 10.651, 8.766 ppm, for 11. The reso-
nance due to OACH2, (H2) protons appear at 5.219 ppm as a singlet
for 6 and at 5.414 and 5.280 ppm as two different singlets for 11.
The observation of downfield/highfield shifts indicate the coordi-
nation of imine nitrogen and phenolic oxygen atoms to Zinc(II)
ions.
3.2. IR spectra and mode of bonding
IR spectra give enough information to elucidate the way of
bonding of the ligands to the metal ions. The main vibration fre-
quencies of the ligands (L1 and L2) and their complexes are listed
in Table 2. The most characteristic vibrations are selected by com-
paring the IR spectra of the ligands with those of their metal com-
plexes. The strong bands at 1608 and 1639 cmꢀ1 for free ligands
1H NMR spectra of Zn(II) complexes (6, 11) were recorded in
CDCl3 and DMDO-d6 solution, respectively (Table 4). The 1H NMR
spectrum of the Zn(II) complexes were compared with the parent
Schiff bases. In the 1H NMR spectrum of 11, each of H(2) and,
H(13) protons appear as two different singlets and each of H(4),
H(5), H(7), H(14) appear as two different doublets, each of H(8),
H(9) appear as two different triplets as a consequence of low
molecular symmetry of 11. But, the triplets from H(8), H(9) protons
and one of the doublets of H(4) protons appear as two different
multiplets since they collide with each other. The resonance due
are due to the azomethine vibration modes, m(C@N). These bands
shift to the higher frequency in the range 1672–1674 cmꢀ1 for
the complexes of L1 and 1663–1674 cmꢀ1 for the complexes of L2
on complexation through two azomethine nitrogens to metal atom
[29]. The upward shifts for the complexes were previously found
for the Schiff base complexes [30]. Ligands display a sharp doublets
O
O
O
O
O
O
Cl
Cl
O
O
N
O
O
Zn
N
N
O
O
N
N
N
O
Zn
Zn
O
O
O
O
O
Cl
Cl
O
Cl
O
O
O
O
O
O
O
O
803
%4.4
1592,92
%55.97
O
O
N
O
O
O
N
+
+
5H
N
O
O
+
4H
+
N
O
429
350
517
%13.2
%9.43
%18.2
O
O
O
+
+
2H
O
+
2H
O
+
O
144
%100
170
298
%34.5
9
314
%28.9
3
%39
Fig. 4. Proposed fragments of [Zn2L1(ClO4)4].

44
K. Karaoglu et al. / Journal of Molecular Structure 922 (2009) 39–45
at 1239–1208 for L1 and 1234–1211 cmꢀ1 for L2 which are assigned
to etheric CAO vibration modes. These bands shift to higher/lower
frequency in the range 1239–1232 for the complexes of L1 and
1239–1206 cmꢀ1 for the complexes of L2 by the coordination
through the two etheric oxygens to metal atom. The perchlorate
salts (3–6, 8 and 9) of the complexes show a triplet (m3 mode) or
a broad band at about 1100 cmꢀ1 (Table 2) due to antisymmetric
stretch, which is indicative of the weakly coordinated/uncoordi-
nated perchlorate ion. The lower energy band at about 625 cmꢀ1
indicates the presence of the coordinated perchlorate ions [31].
In the complexes of 10 and 11, the broad band 1086 cmꢀ1 and
for the perchlorate complexes, respectively [34]. It seems that
two perchlorate ions remain in the inner coordination sphere in
the complexes of 10, 11 while in the complexes of 3–6, 8, and 9
all the perchlorate ions are coordinated to the metal ions in solu-
tion. This is in agreement with the results obtained from the IR
studies.
3.4. Mass spectra
Analysis by ESI mass spectral data indicated ions at m/z 1065.41
(3.8%) [M]+, m/z 990.46 (6.3%) [M-phenyl+2]+ and strong parent
ions at m/z 104.97 (100%) [C6H5HC@N]+ for L1, at m/z 817.42
(14.6%) [M]+, m/z 818.36 (8.9%) [M+1]+, m/z 632.40 (5%)
[MA(OAC10H6HC@NACH3)]+ and strong parent ions at m/z
153.07 (100%) [C10H6HC@N]+ for L2. Analysis by ESI mass spectral
data of L1 complexes indicated ions at m/z 1572.26 (%41.1) [M]+
for 3, m/z 1582.50 (%15.19) [M+2]+ for 4, m/z 1590.14 (%3.16)
M+, for 5, and m/z 1596.14 (%5.28) M+, for 6 (Fig. 3). For the com-
plexes of L2, at m/z 1324.68 (%7.1) [M]+ for 8, at m/z 1334.18 (%9.4)
[M + 2]+ for 9, at m/z 1179.4 (%5.5) [M + 2H2OA2ClO4 + 1]+ for 10,
at m/z 1146.5 (<%1) [MA2ClO4+one]+ for 11 were observed. The
schematic fragmentation of the [Zn2L1(ClO4)4] is depicted in
Fig. 4. All these mass spectral data support the formation of the
Schiff bases and their binuclear transition metal complexes.
1089, 1105, 1147 cmꢀ1 assigned to
m
3(ClAO) indicates both coordi-
ꢀ
nated and noncoordinated (ionic) nature of the ClO4 ion, respec-
tively. The ionic nature is further supported by the appearance of
a sharp band at 624 and 625 cmꢀ1, respectively [32].
The band assignment to various MAN and MAO stretching
vibrations in the lower region of the spectra are difficult as the
ligand vibration interfere. Hence the assignments made here tenta-
tive. In the light of previous results [33], we assign the bands in the
region 501–520 and 567–574 cmꢀ1, to
m(MAN) and m(MAO)
stretching vibrations, respectively. They were observed as weak
bands indicative of the formation of the metal complexes.
3.3. Molar conductivity
The molar conductivity (Km) data, measured at 25 °C using
10ꢀ3 M solutions of the complexes in DMF (Table 1), showed the
presence of ionic and coordinated counterions, since they are in
the range reported in that solvent for 2:1 and non-electrolytes
3.5. Electronic spectra and magnetic moments
The electronic spectrum of L1 and L2 in DMF shows absorption
bands 275 (
e
= 28706 Mꢀ1 cmꢀ1), 321 nm (
e
= 29907 Mꢀ1 cmꢀ1),
Table 5
Electronic absorption spectral data with assignments of Schiff base and its complexes.
Compound
kmax, nm (ꢂMꢀ1 cmꢀ1) in DMF
376 (25492)
Band assignments
Geometry
-
L1, (2)
n ? p*
358 (30328), 321 (29907), 275 (28706)
977 (14),
462 (1645)
p
?
p
?
?
*
[Mn2L1(ClO4)4], (3)
6A1g
4T1g(4G)
4T2g(4G)
Octahedral
6A1g
413 (1904)
LMCT
360 (2300), 316 (2210), 292 (2056)
982 (3),
471 (167)
411 (1983)
p ? p*
3A2g(F) ? 3T2g(F)
3A2g(F) ? 3T1g(F)
LMCT
[Ni2L1(ClO4)4], (4)
Octahedral
358 (2411), 312 (2314), 242 (147)
512 (4112)
411 (3704)
p
?
?
p
*
2Eg
LMCT
2T2g
[Cu2L1(ClO4)4], (5)
[Zn2L1(ClO4)4], (6)
Octahedral
Octahedral
352 (4194), 301 (4095), 242 (660)
405 (2036)
p
LMCT
?
p
*
358 (2610), 316 (2573), 251 (197)
p ? p
*
379 (2665)
358 (4018), 334 (3790), 321 (3848)
n ? p*
L2, (7)
p
?
p*
–
310 (3754)
564 (287),
531 (302),
500 (307),
6A1g ?4T1g(4G)
6A1g ?2T2g(4G)
[Mn2L2(ClO4)4], (8)
6A1g?4A1g
,
4Eg(4G)
Octahedral
445 (300),
LMCT
410 (288)
p ? p*
352 (36168), 312 (40370), 272 (28004)
981 (3)
465 (162)
403 (289)
3A2g(F)?3T2g(F)
3A2g(F)?3T1g(F)
LMCT
[Ni2L2(ClO4)4], (9)
Octahedral
358 (32444),330 (40595), 312 (4000),
p ? p*
271 (24443),
241 (3560)
596 (282)
490 (870)
411 (361)
358 (37729), 334 (36819), 274 (30854245 (4540)
463 (3261),
411 (3222)
z2 ? x2–y2
LMCT
[Cu2L2(ClO4)2](ClO4)2, (10)
[Zn2L2(ClO4)2](ClO4)2, (11)
Square pyramidal
Square pyramidal
p
?
p*
LMCT
p ? p
*
349 (29611), 322 (30265), 272 (23312)
242 (3640)

K. Karaoglu et al. / Journal of Molecular Structure 922 (2009) 39–45
45
358 nm (
310
= 3754 Mꢀ1 cmꢀ1), 321
3790 Mꢀ1 cmꢀ1), 358
cmꢀ1), respectively. The bands appearing at the low energy side
are attributable to n ? * transitions associated with the azome-
thine chromophores. The bands at higher energy arise from
transitions within the phenyl and naphthyl rings [35]. The absorp-
tion bands of the complexes are shifted to longer wavelength region
compared to those of the ligand [36]. A moderate intensive band
observed in the range of 405–413 and 403–490 nm is attributable
to the LMCT transitions of L1 and L2 complexes, respectively. This
shift may be attributed to the donation of the lone pairs of electron
of the nitrogen atoms of the Schiff base to the metal ion (M N).
The electronic spectra of the binuclear Cu(II) complexes are
recorded in DMF solution. The electronic spectrum shows a single
absorption bands at 19531 cmꢀ1 (512 nm) for 5. The positions of
the band are of typical d–d transitions in the octahedral Cu(II) sur-
rounding [37,38]. The absorption spectrum of 10 shows a broad peak
centered at 16779 cmꢀ1 (596 nm) due to z2 ? x2 – y2 transition and
that of Cu(II) exhibits square pyramidal geometry [37,39–42]. The
e
= 30328 Mꢀ1 cmꢀ1), 376 nm (
e
= 25492 Mꢀ1 cmꢀ1) and
References
(e
(e (e =
= 3848 Mꢀ1 cmꢀ1), 334
(e (e
= 4018 Mꢀ1 cmꢀ1), 379 = 2665 Mꢀ1
[1] (a) S. Anbu, M. Kandaswamy, P. Sudhakaran, V. Murugan, B. Varghese, J. Inorg.
Biochem. (2009), doi:10.1016/j.jinorgbio.2008.12.013;
(b) B.D. Wang, Z.Y. Yang, Q. Wang, T.K. Cai, P. Crewdson, Bioorg. Med. Chem. 14
(2006) 1880;
(c) R.D. Jones, D.A. Summerville, F. Basolo, Chem. Rev. 79 (1979) 139.
[2] G. Henrici-Olive, S. Olive, The Chemistry of the Catalyzed Hydrogenation of
Carbon Monoxide, Springer, Berlin, 1984.
[3] H. Dugas, C. Penney, Bioorganic Chemistry, Springer, New York, 1981.
[4] J.D. Margerum, L.J. Miller, Photochromism, Interscience, Wiley, New York,
1971.
[5] W.J. Sawodny, M. Riederer, Angew. Chem. Int. Ed. Engl. 16 (1977) 859.
[6] N. Matsumoto, J.Z. Zhong, H. Okawa, S. Kida, Inorg. Chim. Acta 160 (1989)
153.
[7] D.C. Crans, A.D. Keramidas, H.H. Lity, O.P. Anderson, M.M. Miller, L.M. Lemoine,
S.P. Williams, M. Vandenberg, A.J. Rossomando, L.J. Sweet, J. Am. Chem. Soc.
119 (1997) 5447.
[8] R.C. Burrows, J.C. Bailar, J. Am. Chem. Soc. 88 (1966) 4150.
[9] M. Yildiz, Z. Kilic, T. Hökelek, J. Mol. Struct. 441 (1998) 1.
[10] D.P. Kessissoglou, C.P. Raptopoulou, E.G. Bakalbassis, A. Terzis, J. Mrozinski,
Inorg. Chem. 31 (1992) 4339.
p
p
? p*
[11] S.C. Bhatia, J.M. Bindlish, A.R. Saini, P.C. Jain, J. Chem. Soc. Dalton Trans. (1981)
1773.
[12] M. Calligaris, G. Nardin, L. Randaccio, Coord. Chem. Rev. 7 (1972) 385.
[13] H.S. Maslen, T.N. Waters, Coord. Chem. Rev. 17 (1975) 137.
[14] J. Stewart, E. Lingafelter, C. Acta Cryst. 12 (1959) 842.
[15] D. Chen, A.E. Martell, Inorg. Chem. 26 (1987) 1026.
[16] J.W. Pyrz, A.L. Roe, L.J. Stern, L. Que Jr., J. Am. Chem. Soc. 107 (1985) 614.
[17] J. Costamagna, J. Vargas, R. Latorre, A. Alvarado, G. Mena, Coord. Chem. Rev.
119 (1992) 67.
[18] N.E. Dixon, C. Gazzola, J.J. Watters, R.L. Blakeley, B. Zerner, J. Am. Chem. Soc. 97
(1975) 4131.
[19] C.T. Walsh, W.H. Orme-Johnson, Biochemistry 26 (1987) 4901.
[20] P.A. Vigato, S. Tamburini, D.E. Fenton, Coord. Chem. Rev. 106 (1990) 25.
[21] T.N. Sorrell, Tetrahedron 45 (1989) 3.
[22] V. Amendola, L. Fabbrizzi, C. Mangano, P. Pallavicini, A. Poggi, A. Taglietti,
Coord. Chem. Rev. 219 (2001) 821.
[23] M.K. Taylor, J. Reglinski, D. Wallace, Polyhedron 23 (2004) 3201.
[24] X. Yang, R.A. Jones, Q. Wu, M.M. Oye, W.-K. Lo, W.-K. Wong, A.L. Holmes,
Polyhedron 25 (2006) 271.
[25] G. Venkatachalam, N. Raja, D. Pandiarajan, R. Ramesh, Spectrochim. Acta A 71
(2008) 884.
[26] M. Er, K. Sancak, I. Degirmencioglu, K. Serbest, J. Mol. Struct. 882 (2008)
leff values (1.88 and 1.90 BM) support ferromagnetic type interac-
tions in the Cu(II) complexes and these are consistent with the pro-
posed geometries.
The electronic spectra of the dinuclear Mn(II) complexes exhibit
two absorption bands at 21,645 (462 nm) and 10,235 cmꢀ1(977 nm)
for 3, three absorption bands at 20,000 cmꢀ1 (500 nm) and
18,832 cmꢀ1(531 nm), 17,730 cmꢀ1(564 nm) for 8 suggesting an
octahedral geometry. The band assignments were given in Table 5
and the 6A1g ? 4A1g, 4Eg(4G) (
to be hindered by very intense and broad
m
1) transition for complex 3 is thought
* and n ? * transi-
p
?
p
p
tions. For the complex 3 and 8, the observed magnetic susceptibility
value of 5.27 and 3.79 BM is in accordance with the high spin six
coordinated octahedral arrangement around manganese complex
[38,43]. The low moment of 8 may be ascribed to superexchange
takes place between manganese(II) ions.
_
35.
[27] D.A. Skoog, F.J. Holler, A.T. Nieman, Principles of Instrumental Analysis, 5th ed.,
Harcourt Brace and Company, London, 1998.
Typical octahedral Ni(II) complex is expected to exhibit three
3
3
bands which are assignable to A2g(F) ? 3T1g(P), A2g(F) ? 3T1g(F)
and 3A2g(F) ? 3T2g(F) transitions. The Ni(II) complexes in this study
exhibits only two absorptions bands at 21,231 (471 nm) and
10,183 cmꢀ1 (982 nm) for 4, 21,505 (465 nm) and 10,194 cmꢀ1
[28] R. Ustabasß, U. Çoruh, M. Er, K. Serbest, E.M. Vasquez-Lopez, Acta Cryst. 62
(2006) 5006.
[29] N. Karaböcek, S. Karaböcek, H. Mazlum, I. Degirmencioglu, K. Serbest, Turk. J.
Chem. 28 (2004) 87–94.
[30] (a) B.A. El-Sayed, M.M.A. Aly, A.A.A. Emara, S.M.E. Khalil, Vib. Spectrosc. 30
(2002) 93;
(b) E.M. Nour, A.A. Taha, A.S. Al-Naimi, Inorg. Chim. Acta 141 (1988) 139.
[31] (a) C. Lodeiro, R. Bastida, E. Bertolo, A. Macias, A. Rodriguez, Inorg. Chim. Acta
267 (1998) 55;
(981 nm) for
9
and assignable to 3A2g(F) ? 3T1g(F) and
3A2g(F) ? 3T2g(F) transitions for the two complex, respectively.
3
The A2g(F) ? 3T1g(P) transition was hindered by the intense
(b) E.-Q. Gao, G.-M. Yang, J.-K. Tang, D.-Z. Liano, Z.-H. Jiang, S.-P. Yan,
Polyhedron 18 (1998) 3643;
(c) M.G.B. Drew, J. Nelson, S.M. Nelson, J. Chem. Soc. Dalton Trans. (1981) 1678.
[32] M. Shebl, Spectrochim. Acta A 70 (2008) 850.
n ? p* transitions. From these transitions and magnetic moment
values (2.45 and 2.96 BM) a high spin octahedral geometry is as-
signed for 4 and 9 [44].
UV/visible spectra of the binuclear Zn(II) complexes (6 and 11)
were recorded in DMF solution showed two main peaks at 405,
358–241 and 411, 358–245 nm, respectively. These peaks were as-
signed to Zn–L charge-transfer transition as well as intra ligand
transition, respectively.
[33] H. Temel, U. Cakır, I.H. Ugras, Synth. React. Inorg. Met.-Org. Chem. 34 (4)
(2005) 819.
[34] W.J. Geary, Coord. Chem. Rev. 7 (1971) 81.
[35] T.R. Holman, M.P. Hendrich, L. Que, Inorg. Chem. 31 (1992) 937.
[36] J. Manonmani, M. Kandaswamy, V. Narayanan, R. Thirumurugan, S. Shanmuga
Sundura Raj, G. Shanmugam, M.N. Ponnuswamy, H.K. Fun, Polyhedron 20
(2001) 3039.
[37] S.A. Sallam, A.S. Orabi, B.A. El-Shetary, A. Lentz, Trans. Met. Chem. 27 (2002)
447.
Acknowledgements
[38] A.B.P. Lever, Inorganic Electronic Spectroscopy, Elsevier, NewYork, 1971.
[39] C.T. Yang, M. Vetrichelvan, X.D. Yang, B. Moubaraki, K.S. Murray, J.J. Vittal, J.
Chem. Soc. Dalton Trans. (2004) 113.
[40] B. Sreenivasulu, M. Vetrichelvan, F. Zhao, S. Gao, J.J. Vittal, Eur. J. Inorg. Chem.
(2005) 4635.
This work was supported by the Scientific and Technical
Research Council of Turkey (TUBITAK) under project No. 107T383.
[41] K.S. Bharathi, A.K. Rahiman, K. Rajesh, S. Sreedaran, P.G. Aravindan, D.
Velmurugan, V. Narayanan, Polyhedron 25 (2006) 2859.
[42] V. Philip, V. Suni, M.R.P. Kurup, M. Nethaji, Polyhedron 25 (2006) 1931.
[43] A.S. El-Tabl, F.A. El-Saied, A.N. Al-Hakimi, Trans. Met. Chem. 32 (2007) 689.
[44] S. Saydam, E. Yilmaz, Spectrochim. Acta A 63 (2006) 506.
Appendix A. Supplementary data
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.molstruc.2009.01.037.