synthesis and characterization of divalent transition...
TRANSCRIPT
97
Synthesis and Characterization of Divalent Transition Metals Complexes of
Schif Bases Derived From O-Phenylenediamine and Benzoylacetone and
Related Species
A. A. Ahmed, S. A. BenGuzzi., A. A. EL-Hadi
*
Chemistry Departments, Faculty of Science, University of Garyounis, Benghazi, Libya
*Chemistry Departments, Faculty of Arts & Science Obaree, Sabha University, Libya
ABSTRACT
The Schiff base ligands and their complexes of divalent metals of Ni(II), Co(II)
and Cu(II) were investigated in terms of synthesis, elemental analysis, molar
conductivity, thermal analysis, infrared spectra, ultraviolet-visible and magnetic
susceptibility measurements. The ligands have been synthesized by condensation
of benzoylacetone and ethylenediamine, o-phenylenediamine and 1,6-
hexanediamine to gives H2L1 = C22H24N2 -
bis(benzoylacetone)ethylenediamine]; H2L2
= C26H24N2O2 -(benzoylacetone)-o-
phenylenediamine]; H2L3 = C26H32N2O2 -bis (benzoylacetone)-1,6-
hexanediamine] respectively. The fourth ligand is formed by the condensation of
benzoin and o-phenylenediamine H2L4
=C34H28N2O2, -bis(Benzoin)-o-
phenylenediamine]. The ligands and their complexes have been synthesized by two
different methods and their geometries were investigated. A synthesis and
characterization of novel ligand and complexes of benzoin derivatives has been
achieved. The study also confirmed the formation of mon- and binuclear metal.
The binuclear metal complexes are synthesized by new methods. The researcher
recommended that the mentioned complexes may have biological activity.
Key Words: Synthesis and Characterization; O-phenylenediamine; binuclear metal
complexes
INTRODUCTION
Schiff bases offer a versatile and flexible series of ligands capable to bind with various metal
ions to give complexes with suitable properties for theoretical and/or practical applications. Since
the publication of Schiff base complexes, a large number of polydentate Schiff base compounds
have been structurally characterized and extensively investigated, (Middleton, Masters, &
Wilkinson, 1979). Schiff base ligands and their metal complexes have been extensively studied
over past few decades. Of the various classes of Schiff base which can be prepared by
condensation of different types of amines and carbonyl compounds salicylaldimines, potential O,
Garyounis University Press
Journal of Science and Its Applications
Vol. 1, No. 1, pp 79-90, February 2007
08
N-donors derived from salicyldehyde and primary amines, are very popular due to diverse
chelating ability (Long, 1995).
Copper(II)- salicylaldimine complexes play important roles in both synthetic and structural
research because of their preparative accessibility and structural diversity (Garnovskii,
Nivorozhkin, & Minkin, 1993). In addition to the varied magnetic property and catalytic activity,
the metal-Schiff base complexes can also serve as efficient models for the metal containing sites
in metallo-proteins and -enzymes (Jacobsen, Zhang, Muci, Ecker, & Deng 1991; Espinet,
Esteruelas, Oro, Serrano, & Sola, 1992). Tetradentate Schiff bases with a N2O2 donor atom set
are well known to coordinate with various metal ions, and this has attracted many researchers.
Complexes of Schiff base ligands have been studied for their dioxygen up take and oxidative
catalysis. Also complexes of transition metals(II), which involve derivatives of salicyldehyde and
diamine, have gotten considerable attention. This is because of their potential as catalysts for the
insertion of oxygen into an organic substrate (Abd-Elzaher, 2001). Synthesis, X-Ray and
magnetic properties of dinuclear Ni(II) and Cu(II) complexes bridged by the Azo-2,2’-
bispyridine ligands has been considered, (Campos-Fernandez, Galan-Mascaros, Smucker, &
Dunbar, 2003). They studied the magnetic properties of these dinuclear paramagnetic complexes
in details and have provided an opportunity for probing the ability of this ligand to mediate
exchange interactions between paramagnetic metal centers. Many ketone and ß-diketones are
condensed with amine and diamines for forming a Schiff base and their complexes (Doherty,
Errington, Housley, Ridland, Clegg, & Elsegood, 1998; Yamada, Misawa, Arai, & Matsumoto, 2004;
Fuerst & Jacobsen, 2005) and (Ochiai, Lin,. The present study aimed to investigate the reaction of
several tetradentate Schiff bases derived from the condensation of o-phenylenediamine with
salicyldehyde, 2-hydroxy-1-naphthaldhyde, or o-hydroxyacetophenone with nickel, cop per and
zinc ions. The pre pared ligands and complexes have been characterized by IR, 1H NMR, MS,
uv/vis spectra as well as el e mental analysis.
EXPERIMENTAL
All materials and reagents used in this study were laboratory pure chemicals. They include,
Benzoin, Benzoylacetone, ethylenediamine o-phenylenediamine, 1,6-hexandiamine pipeiridine.
The solvents used are ethanol, acetone, petroleum either 60-80C°, dimethylformamide (DMF),
chloroform (CHCl3) distilled water. The metal chlorides are cobalt chloride (CoCl2.6H2O), nickel
chloride (NiCl2.6H2O) and copper chloride (CuCl2.2H2O).
Synthesis of The Schiff Base Ligands:
The amines were dissolved in absolute ethanol (40 cm3), the ethanolic solution of amines was
refluxed with ketone. The reaction molar ratio was 1:2 (amine to ketone). A few drops of
pipiridine as condensing agent are added. After refluxing the mixture for about 5h, solid crude
was formed which is filtered off and recrystallized from hot ethanol and dried in desiccated over
anhydrous CaCl2.
A. A. Ahmed et al.
08
Synthesis of Schiff Base Complexes:
Schiff bases complexes under investigation were synthesized as follows; a suitable ligand is
dissolved in (20 cm3) ethanol and added to a metal salt ethanolic solution (20 cm
3). The reaction
molar ratio is (1:1) or (1L: 2M). The mixture is refluxed for 10h; the volume of the mixture is
reduced to one-third. On cooling a crude product is formed, which is collected by filtration and
washed several times with ethanol and dried over anhydrous CaCl2.
Measurements:
All the Schiff base ligands and their complexes under investigation, were subjected to (C, H
and N) elemental analysis which performed at analytic unit of the central laboratory of Tanta
University (Egypt) and laboratories of RASCO company Libya. The melting point was measured
in capillary tubes Philip Harris, Shenston-England, serial NO.B/A_211. The molar conductance
values were calculated in (10-3
M) in DMF or Chloroform solution by using digital conductivity
meter CMD 650. The magnetic moment measurements were determined by using a modified
Goy type magnetic balance Hertz SG8 SHJ, England. The IR spectra were recorded using a
Perkin-Elmer 1430 spectrophotometer using KBr Discs, at Menofia University, Shibin El-Kom
(Egypt). The electronic spectra were measured in DMF or Chloroform solution by using a 640S
UV-Vis spectrophotometer using 1cm matched silica cells.
RESULT AND DISCUSSION
The Schiff base ligands under investigation were formed by the condensation reaction of
Benzoylacetone with Ethylenediamine, o-phenylenediamine and 1,6-hexanediamine to obtained
H2L1
= [C22H24N2O2], H2L2
= [C26H24N2O2] and H2L3
= [C26H32N2O2] respectively. The fourth
Schiff base ligand H2L4
= [C34H28N2O2] formed by the condensation of o-phenylenediamine with
Benzoin. The structure of Schiff base ligands are shown below.
N
NOH
OH
N
NOH
OH
OH
OH
N
N
N N
OH
H
OHH
H2L1 H2L2 H2L3 H2L4
Elemental Analysis:
Physical characteristics and elemental analysis of C, H and N of the compounds considered are
listed in Table 1. The results of C, H and N percentage are in accordance with the composition
suggested for the most complexes. An attempt has been made to isolate the second ligand (H2L2
=
[C26H24N2O2]) as pure compounds was unsuccessful, nevertheless, second ligand complexes has
been prepared analytically pure.
Synthesis and Characterization of Divalent Transition metals Complexes of
Schif Bases Derived From O-Phenylenediamine and Benzoylacetone and
08
Table 1 . Elemental analysis, Color, M.P, and molar conductivity of the compounds under
investigation.
Compound M.wt color Cond.
scm2mol
-1 m.p °C
Found
(calc.)
C% H% N%
H2L1
348 White - 177
75.86
(75.40)
6.89
(7.35)
8.04
(7.96)
H2L2
396 Yellow - 50
unsatisfactory
H2L3
404 Pale
yellow - 100
77.22
(76.11)
7.92
(7.83)
6.93
(7.38)
H2L4
496 Pale
orange - 90
82.25
(82.85)
5.64
(4.71)
5.60
(6.65)
[NiL1(H2O)2] 440 Brown 10.17 150
59.40
(59.90)
4.64
(5.80)
7.02
(6.35)
[Cu2L1Cl2]8H2O 687 Brown 0.03 206
39.96
(38.42)
4.62
(4.36)
7.32
(4.07)
[Ni2L1 Cl2]4H2O 606.7 Brown 37.97 180
43.58
(43.54)
5.53
(4.94)
5.40
(4.61)
[Cu2L1(H2O)2]2OH 543 Blue 156 180
49.50
(48.50)
3.24
(5.15)
5.12
(5.15)
[Co2L2 Cl4 (H2O)2]
7H2O 781.8 Blue 45.07 140
39.20
(39.90)
4.08
(4.86)
4.78
(3.58)
[Ni (H2L2)Cl2] 525.7
Pale
green 18.07 60
59.93
(59.34)
4.40
(4.56)
5.00
(5.32)
[Cu2L2Cl2]4H2O 664 Red 44.37 92
45.62
(46.98)
4.45
(4.51)
5.03
(4.21)
[Cu (H2L3)Cl2] 2H2O 574.5 Green 1.05 210
54.31
(54.30)
4.30
(6.26)
4.78
(4,87)
[Ni (H2L3)Cl2]4H2O 605.7
Pale
green 20.87 200
50.55
(51.51)
6.98
(6.60)
4.24
(4.62)
[Co2(H2L3)(H2O)8]4Cl 807.8
Dark
green 68.97 143
36.99
(38.63)
5.31
(5.94)
2.75
(3.46)
[Ni2 (H2L3)(H2O)8]4Cl
C2H5OH 853.4
Olive
green 493 220
39.35
(39.39)
7.06
(5.73)
2.17
(3.28)
[Cu2L3(H2O)4]2Cl 672 yellow 770 150
47.40
(46.42)
4.03
(5.65)
6.19
(4.16)
A. A. Ahmed et al.
08
Molar Conductance:
The molar conductance for the complexes measured in 10-3
M solution in DMF and
chloroform as solvents at room temperature (29-31ºC). The molar conductivity was applied to
help in the investigation of the geometrical structures of the complexes. The molar conductivity
values are given in Table 1. Some complexes showed a lower molar conductivity values in the
range 0.03-44.37Scm2mol
-1 which indicated their non-electrolytic nature. Other complexes found
to be a higher electrolyte with the values 68.97,156, 493 and 770Scm2mol
-1, this result is
demonstrated that the complexes have a binuclear nature (Spinu, Kriza; 2000).
Thermal Analysis:
Thermal methods of analysis open a new possibility for the investigation of metal complexes.
They include differential thermal analysis (DTA) and thermogravimetric analysis (TGA). The
Thermal analysis data are collected in Table 2. The DTA of [Cu2L2Cl2] 4H2O complex showed
that the hydration water peak appears at 21-70C°. This peak did not appear for the other complex
[Cu2L1(H2O)2]2(OH). In addition the different position of melting points and partial
decomposition of the two complexes, at 225ºC for complex [Cu2L1(H2O)2]2(OH) may be due to
decomposition of partial organic ligand with two coordinated water molecules and at 283ºC of
complex [Cu2L2Cl2]4H2O due to partial organic ligand, which indicated the difference of organic
ligands for them. The final endothermic peak of two complexes at region >300°C may be due to
loses weight which assigned to lose of organic species of the ligand or formation of metal oxide.
The TGA of complex [Cu2L2Cl2] 4H2O confirmed the lost of weight at temperature range 28-
142°C corresponding to loss of hydrated water molecules which is assigned to (Calc.5.7%)
corresponding to 2H2O (found 6.03%) which confirmed from the endothermic peak at
temperature range 21-70C° in the DTA curve. In addition the peak at 144-300°C range, this may
be due to weight lost of partial organic ligand with two water molecules. For the [Cu2L2Cl2]4H2O
the weight lost at the 300-338°C may be due to the (Calc. 10.00%) corresponding to Cl2 (found
12.14%). In addition to the final peak at the temperature ranging at 486-573°C which
corresponding to 2CuO lost (Calc. 26.22%; found 28.04%), which is indicating the binuclear
nature of the complex.
The DTA analysis of [Co2L2Cl4(H2O)2]7H2O complex showed two endothermic peak at 183-
230°C, which assigned to loss of two coordinated water molecules. The broad endothermic peak
at 260-390°C assigned to decomposition of organic partial of Schiff base ligand. The
endothermic peak at 552-697°C regions is due to the decomposition of complex and indicated the
formation of metal oxide. The TGA of [Co2L2 Cl4 (H2O)2], curve showed the loss of weight at
27-198C° range due to lost of two coordinated water molecules corresponding to( Calc.4.6% ;
found 3.87% ), which confirmed from the two endothermic peak of DTA. In addition the peak at
the temperature ranging 199-259°C, is may be due to the weight lost of 2HCl molecules,
corresponding (Calc.9.3%; found 7.59%). The peak at 259-391°C, is assigned to the formation of
metal oxide 2CoO corresponding to (Calc.19.21%; found 18.6%). The final peak at 392-651°C is
assigned to the lost of partial organic ligand, corresponding to (Calc.40.67%; found 42.75%).
Synthesis and Characterization of Divalent Transition metals Complexes of
Schif Bases Derived From O-Phenylenediamine and Benzoylacetone and
08
Table 2. Thermal analysis (DTA and TGA) of some Schiff base complexes under
investigation.
Complex Tmep-range
°C
DTA
peaks
Tmep-
range
°C
TGA (loss %) Loss
species Found Calc.
[Cu2L1(H2O)2]2OH
225°C Endo. — — — 2(OH)
398ºC Endo. — — — Coord.2H2O
449 ºC Endo. — — — Metal oxide
[Cu2L2Cl2] 4H2O
21-70°C Endo. 28-142°C 6.03% 5.7% 2H2O
238ºC Endo. 144-300°C — — Organic
specie+H2O
>300 ºC Endo. 300-338°C 12.14% 10.0 % Cl2
— — 486-573°C 28.04% 26.22% 2CuO
[Co2L2Cl4 (H2O)2]
7H2O
183-230°C Endo. 27-198°C 3.87% 4.6% 2H2O
260-390°C Endo. 199-259°C 7.59% 9.3% 2HCl
552-697 °C Endo. 259-391°C 18.6% 19.21% 2CoO
— — 392-651°C 42.75% 40.67% Organic
specie
[Cu(H2L3)Cl2]2½H2O
50-180°C Exeo. 145-264°C 9.85% 7.83% 2½H2O
260-348°C Endo. 265-337°C 19.9% 16.9% Cu(OH)2
482-608°C Endo. 338-620°C — — Organic
specie
Infrared Spectra:
The IR spectra of diagnostic importance of the complexes are given in Table 3. The solid state
IR spectra of complexes compared with those of ligands indicated that the ν(C=N) stretching
vibration band at region 1531-1664cm-1
is shifted to lower frequencies in most complexes as
excepted. In contrast there are three complexes shifted to higher frequencies, which indicated
that the ligands coordinated to the metal ions through nitrogen atom of the azomethine group. In
general the observed IR bands of Schiff bases and their complexes are in conformity with the
previously reported results (Keypour, Salehzadeh, & Parish, 2002; Raman, Ravichandran, &
Thangaraja, 2004; Chandra & Kumar 2005).
The presence of sharp band corresponding to the remaining hydroxyl group at 3400cm-1
but
it is obscured by the presence of water molecules bands. This was appeared for the most
complexes and a very broad band at about 3100-3500cm-1
region, which is associated with
coordinated or solvent water molecules.
A. A. Ahmed et al.
08
The other bands appeared at 1323-1427cm-1
region assigned to the ν(C—O), which are shifted
to a higher frequency after complexation with central metal ions, compared to the free ligands in
which was noted at 1261-1315cm-1
. In addition the two bands at 729-511 and 531-442cm-1
, is
attributed to the ν(M—O) and ν(M—N) respectively.
Moreover new bands appeared in some complexes in the 220-290cm-1
regions which is
assigned to ν(M—Cl) vibration, which indicated the formation of (M —Cl) coordinated bond.
The IR spectra of [Cu2L1Cl2] 8H2O complex exhibit a strong band at 1568cm
-1 which is assigned
to the ν(C=N) stretching, because this band is shifted to lower frequency by 36cm 1
compared to
free ligand, indicating that the ligand coordinated to the metal ion through nitrogen atom of the
azomethine group and probably dianionic form. The broad band around 3425cm-1
indicating the
presence of coordinated or lattice water in the complex. The spectrum reversals a weak band at
1399cm-1
which is attributed to ν(C—O) vibration, again this band is shifted to higher value
compared to the free ligand due to formation (C—O—M) bond. In addition three new bands in
the regions 527,466 and 221cm-1
were emerge, which are probably due to the formation of (Cu—
O), (Cu—N) and (Cu—Cl) bond respectively.
Table 3. Infrared bands assignments (cm-1
) of the compounds under investigation.
The compound ν(C=N)
cm-1
ν( C-O)
cm-1
ν(OH)
cm-1
ν(M-O)
cm-1
ν( M-N)
cm-1
ν( M-Cl)
cm-1
H2L1
1604 1292 3424 - - -
H2L2
1576 1315 3404 - - -
H2L3
1592 1291 3429 - - -
H2L4
1673 1261 3415 - - -
[NiL1(H2O)2] 1585 1427
3422
560
495
-
[Cu2L1Cl2]8H2O 1568 1399 3425 527 466 221
[Ni2L1Cl2]4H2O 1585 1356 3384 561 495 289
[Cu2L1(H2O)2]2(OH) 1567 1323 3448 526 468 -
[Co2L2Cl4 (H2O)2]7H2O 1555 1405 3367 518 466 290
[Ni (H2L2) Cl2] 1558
1399 3431 587 531 220
[Cu2L2Cl2] 4H2O 1531 1399 3447 511 464 221
[Cu (H2L3) Cl2] 2H2O 1552 1366 3444 701 457 266
[Ni (H2L3) Cl2] 4H2O 1605 1396 3421 725 445 220
Synthesis and Characterization of Divalent Transition metals Complexes of
Schif Bases Derived From O-Phenylenediamine and Benzoylacetone and
08
[Co2 (H2L3)(H2O)8]4Cl 1598 1385 3553 729 420 -
[Ni2 (H2L3) (H2O)8]4Cl.
C2H5OH 1599 1398 3401 714 442 -
[Cu2L3(H2O)4]2Cl 1571 1390 3152 657 473 -
[Co(H2L4) Cl2]4H2O 1664 1335 3382 639 464 259
[Ni(H2L4) Cl2] 1630 1334 - 638 478 261
[CuL4]2½ H2O 1628 1344 3424 636 551 -
Electronic Spectra and Magnetic Moment:
The electronic absorption spectra and magnetic moment values are often very helpful in the
evaluation of results provided by other methods of structural investigation. Information about
geometry of the complexes around the Cu(II), Co(II) and Ni(II) ions was obtained from electronic
spectra and from values of the magnetic moments. The assignment of the bands of the electronic
spectra of the complexes is listed in Table 5. The electronic absorption spectra of the Schiff base
ligands and its complexes were recorded at room temperature using (DMF) and (CHCl3) as
solvents.
The electronic spectra of the [NiL1(H2O)2] complex shows a bands in the regions 11025,
17921and 22371cm-1
corresponding to the 3A2g→
3T1g(P),
3A2g(F)→
3T1g(F) and
3A2g(F)→
3T2g(F) transition respectively. Our results are in good agreement with those reported
for an octahedral geometry around Ni(II) ion. There is an extra band at 25906cm-1
due to → *
transition of aromatic rang or azomethine group. The appearance of a band at 17391cm-1
due to 3A2g(F)→
3T1g(F) transition favors an octahedral geometry,
for the [Ni(H2L
2)Cl2] complex, also
the absence of any band below 10,000cm-1
eliminated the possibility of a tetrahedral environment
in the two complexes above. The absorption band at 27027cm-1
is due to → * transitions of
aromatic rang or azomethine group.
The electronic spectrum of copper (II) complex [Cu(H2L3) Cl2]2H2O showed one band at
15384 cm-1
which is assigned to 2Eg→
2T2g transition, which is conformity with octahedral
geometry. The value of magnetic moment 1.8 B.M is due to one unpaired of 3d9
electronic
configuration in an octahedral complex of Cu(II) ion.
The electronic spectra of the complex [Ni(H2L3)Cl2]4H2O is compatible with an octahedral
geometry. Three absorption bands were observed for the complex at 11049.7, 17241 and
26666.6cm-1
which attributed to the 3A2g→3T1g (P), 3A2g (F) →
3T1g (F) and
3A2g (F) →
3T2g
(F) transition respectively. On the basis of spectral bands an octahedral geometry is therefore
proposed for the Ni(II) ion. The value of magnetic moment at room temperature is 3.1B.M,
which is consistent with an octahedral field. The Co(II) complex [Co(H2L4)Cl2] showed two
A. A. Ahmed et al.
09
bands at 14925cm-1
and 18050cm-1
which are assigned to 4T1g→
4A2g and
4T1g→
4T1g(P)
transitions respectively which indicates an octahedral geometry of this complex. The bands of
Ni(II) complex [Ni(H2L4)Cl2] was appeared at 17391cm
-1, which may be due to the
3A2g →
3T1g
transition favors an octahedral geometry, for the Ni(II)complex. The nonexistence of any band
under 10,000cm-1
is an indication for that the possibility of a tetrahedral geometry around Ni(II)
ion in this complex is remote. The complex has magnetic moment value of 3.6 B.M, which is
compatible with an octahedral complex. The Cu(II) complex [CuL4]2½H2O has an absorption
band at 24096cm-1
a well defined shoulder for 2B1g→
2B2g, which strongly favor the square
planar geometry around the metal ion. The absorption band at 27027cm-1
assigned to → *
transition. This further supported the magnetic susceptibility value of 1.8 B.M due to the
unpaired of electron in octahedral geometry of Cu(II) ion.
The electronic spectra of the nickel complex [Ni2L1.2Cl]4H2O, showed a band at 17699cm-1
is due to 1A1g→1B1g transition, which also indicates a square planar geometry. The absence of
any band below 10,000cm-1 refer to no tetrahedral geometry around two metal ions. Moreover
low magnetic moment value 1.8 B.M of the this complex due to anti-ferromagnetic interaction
between magnetic filed of two Ni(II) ions. The [Cu2L1(H2O)2]2(OH) complex solution displays
two band at 11037 and 25706cm-1 corresponding to 2B1g→2A1g and 2B1g →2B2g transitions
respectively, which strongly favor the square planar geometry around two metal ion. The
magnetic moment value at room temperature of this complex is 1.2 B.M lower than 1.7 B.M due
to anti-ferromagnetic interaction between two Cu(II) ions, which is indicated the formation of
binuclear complex. The electronic spectra in DMF solution of [Co2(H2L2)4Cl (H2O)] complex
exhibit two bands at 15267 and 16393cm-1, which are assigned to 4T1g (F)→4A2g (F) and 4T1g
(F)→4T1g (P) transitions respectively, indicated an octahedral configuration around Co(II) ion.
The octahedral geometry of the Co(II) complex is further confirmed by the magnetic moment
4.89 B.M the lower magnetic moment value of this complex about 3.8 B.M is may be due to anti-
ferromagnetic interaction between two Co(II) ions. The electronic absorption spectra of
[Cu2L2Cl2]4H2O showed two absorption band at 10989 and 25705cm-1 corresponding to 2B1g
→ 2A1g and 2B1g →2B2g transitions respectively, which indicated the square planar
configuration around the two Cu(II) ions. An absorption band at 26315cm-1 may be due to → * transitions of aromatic rang or azomethine group. In addition the lower magnetic value
1.16 B.M is attributed to the anti-ferromagnetic moment interaction between two central metal
ions, this is an indication of the formation binuclear complex. Some of complexes structures are
shown below.
Synthesis and Characterization of Divalent Transition metals Complexes of
Schif Bases Derived From O-Phenylenediamine and Benzoylacetone and
00
O
O
NiH
2O
N
N
OH2
N
N
O
Cu
O Cl
Cl
Cu
N
N
O
Ni
O Cl
Cl
Ni
N
N
OH
H
OH
H
NI
Cl
Cl
N
N
Co
Cl O
Co
O OH2
OH2
Cl
ClCl
Table 4. Electronic Spectra and magnetic moment of the Schiff base complexes under
investigation.
The complex nm
Lmol-1
cm-1
ν cm
-1 µeff
B.M Geometry
[NiL1(H2O)2]
907
558
447
386
0.05
0.207
2.334
2.109
11035
17921
22371
25906
— Octahedral
[Cu2L1Cl2]8H2O
545
430
385
1.638
2.446
2.305
26178
23255
25974
— Square planar
[Ni2L1Cl2]4H2O
565
454
385
0.392
2.456
2.121
17699
22026
25974
1.8 Square planar
[Cu2L1(H2O)2]2(OH)
389
906
0.346
0.079
25706
11037
1.2 Square planar
[Co2L2Cl4 (H2O)2]7H2O
610
655
0.767
1.038
16393
15267 3.8 Octahedral
A. A. Ahmed et al.
07
[Ni(H2L2)Cl2] 575
370
0.08
1.916
17391
27027 — Octahedral
[Cu2L2Cl2]4H2O
380
395
910
2.276
2.176
0.301
26315
25316
10989
1.16 Square planar
[Cu(H2L3)Cl2]2H2O 650 0.176 15384 1.8 Octahedral
[Ni(H2L3)Cl2]4H2O
808
788
898
0.08
0.06
1.98
17241
11049
26666
3.1 Octahedral
[Co2 (H2L3)(H2O)8]4Cl
650
600
375
0.633
0.564
2.003
15384
16666
26666
— Octahedral
[Ni2(H2L3) (H2O)8]4Cl.
C2H5OH
402
389
0.155
0.219
24875
25706 1.8 Octahedral
[Cu2L3(H2O)4]2Cl
888
888
2.99
0.148
22593
18155 0.8 Square planar
[Co(H2L4)Cl2]4H2O
605
670
0.267
0.370
16528
14925 — Octahedral
[Ni(H2L4)Cl2] 575 0.084 89878 3.6 Octahedral
[CuL4]2½ H2O
370
415
440
1.952
0.343
0.316
89889
88878
88989
1.8 Square planar
CONCLUSION
The synthesized novel ligands and their complexes are examined in terms of elemental
analysis, molar conductivity, thermal analysis, infrared spectra, and ultraviolet-visible and
magnetic susceptibility measurements. The analysis confirmed the formation of mon- and
binuclear metal complexes.
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