- Email: [email protected]
Complexation behavior of Schiff base toward transition metal ions
Microchemical Journal 81 (2005) 191 – 194 www.elsevier.com/locate/microc
Complexation behavior of Schiff base toward transition metal ions S.M. Ben-sabera, A.A. Maihubb, S.S. Huderec, M.M. El-ajailyd,* a
Pharmaceutical Chem. Department, Faculty of Pharmacy, Gar-Younis University, Benghazi, Libya b Chemistry Department, Faculty of Science, Al-Fateh University, Tripoli, Libya c The Man Great River Project (GMRUA), Libya d Chemistry Department, Faculty of Science, Gar-Younis University, Benghazi, Libya Received 21 April 2004; received in revised form 26 February 2005; accepted 1 March 2005 Available online 26 May 2005
Abstract Complexes of Iron, Cobalt, Nickel and Zinc ions with the Schiff base derived from p-dimethylaminobenzaldehyde and o-aminobenzoic acid were synthesized and investigated by several techniques using elemental analyse (C,H,N), molar conductance measurements, infrared and electronic spectra. The elemental analysis data suggest the stoichiometry to be 1:1 [M:L] ratio formation. The molar conductance measurements reveal the presence of non-electrolytic nature complexes. Infrared spectral data agreed with the coordination to the central metal ions through both the nitrogen atom of the azomethine and oxygen atom of the carboxyl group of the 2-aminobenzoic acid moiety. The electronic spectral data suggest the existence of octahedral geometry for Fe(III) complex, square planar geometry for Co(II) and Ni(II) complexes and tetrahedral geometry for Zn(II) complex. D 2005 Elsevier B.V. All rights reserved. Keywords: Complexation behavior; Schiff base; Transition metal ions
1. Introduction Complexes of various metal ions with Schiff bases derived from 3-aminomethyl-4-amino-5-mercapto-1,2,4-triazole and thiocarbohydrazones have been extensively studied [1]. There is growing interest in the studies on meal complexes of Schiff bases derived from triazoles which are biologically important ligands [2]. The unsymmetrical Schiff base such as 1-hydroxy2-acetonaphthoneacetylacetoneethylenediamine and its complexes with some transition metal ions have been prepared and investigated by different techniques [3]. The complexes of Co(II), Ni(II) and Cu(II) ions with the Schiff bases derived from the condensation of salicylaldehyde and o-aminophenol or 2-aminobenzoic acid were synthesized and characterized by using different techniques; in particular the elemental analysis, molar conductance measurements, infrared and electronic spectra. The square planar geometry for all metal complexes were suggested [4,5].
As a continuation of our previous work on ‘‘The experimental studies on some Schiff bases complexes’’, we are reporting here the complexation behavior of Schiff base derived from the condensation of p-dimethylaminobenzaldehyde and o-aminobenzoic acid with Fe(III), Co(II), Ni(II) and Zn(II) ions.
2. Experimental 2.1. Solvents and reagents All chemicals used in this investigation were laboratory pure including FeCl3 I 6H2O, CoCl2 I 6H2O, NiCl2 I 6H2O, ZnCl2, NH4OH, C2H5OH, DMSO, DMF, CHCl3, pdimethylaminobenzaldehyde and o-aminobenzoic acid and double distilled Water. 2.2. Physical measurements
* Corresponding author. E-mail address: [email protected] (M.M. El-ajaily). 0026-265X/$ - see front matter D 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.microc.2005.03.001
The elemental analyses of C, H and N were performed in advanced laboratory of chemical analysis, Al-
192
S.M. Ben-saber et al. / Microchemical Journal 81 (2005) 191 – 194
Table 1 Elemental analysis and molar conductances of the Schiff base and its complexes Ligand/complex
Molecular weight
%C Calculated
Found
Calculated
Found
Calculated
Found
LH [FeL(OH)2(H2O)2] I 2H2O [CoL(OH)(H2O)] I H2O [NiL(OH)(H2O)] I 4H2O [ZnL(OH)(H2O)] I 2H2O
268 429 379 432.7 422.40
71.64 44.75 50.65 44.37 47.49
71.70 44.83 50.29 43.64 46.48
5.97 5.82 5.27 6.00 5.33
5.20 5.20 4.60 6.81 5.25
10.44 6.53 7.38 6.47 6.93
10.33 7.34 8.38 7.18 7.80
LH = free Schiff base. MC = molar conductivity (V
1
cm2 mol
%H
%N
MC
– 3.40 5.20 7.90 10.1
1
).
Fateh University, Tripoli, Libya. The molar conductance measurements carried out in DMF solvent using conductivity meter model CMD650 digital meter. Infrared spectra were recorded using KBr disc technique on IFS-25DPUS/IR spectrometer (Bruker). The electronic absorption spectra were measured by using a PerkinElmer lambda 4h spectrophotometer in 1 cm matched silica cells. 2.3. Preparation of Schiff base The Schiff base used was prepared by mixing an ethanolic solution (50 ml) of 1.49 g (0.01 mol) of pdimethylaminobenzaldehyde with 1.37 g (0.01 mol) of oaminobenzoic acid in the same volume of ethanol. The mixture then refluxed with stirring for 2 h. The precipitate was collected by filtration through Buchnner funnel, recrystallized from ethanol, and dried at room temperature with 85% yield.
2.4. Preparation of complexes The Schiff base complexes under investigation were prepared by mixing 25 ml ethanolic solution of the Schiff base (0.01 mol; 2.86 g) with 25 ml of the ethanolic solution of the metal salts (0.01 mol); FeCl3 I 6H2O (2.80 g) CoCl 2 I 6H 2 O (2.38 g), NiCl 2 I 6H 2 O (2.37 g), ZnCl2(1.36 g). If the solid complexes did not separate, few drops of NH4OH solution were added to adjust the pH = 6 –8. The obtained mixture was refluxed with stirring for 2 h, and then kept overnight to insure the complete reactions. Thus, the formed complexes were filtered, collected and then washed several times with hot ethanol until the filtrate becomes colorless. The complexes were dried in a desiccator over anhydrous calcium chloride under vacuum. The yield ranged from 70% to 80%. The complexes are insoluble in CH3OH and CH3CH2OH but soluble in CHCl3 and DMF. The dried complexes were subjected to elemental and spectroscopic analyses.
3. Results and discussion The condensation of p-dimethylaminobenzaldehyde with o-aminobenzoic acid in boiling ethanol yields one Schiff base compound. The chemical equations concerning the formation of the Schiff base and the complexes represented as follows:
H NH2 +
O N O
OH
H N
H Mn+
N
N(CH3)2 NH4OH
O
O
N(CH3)2
N(CH3)2
OH
O
H
O
O
N(CH3)2 .nH2O
M(OH)1 or 2 (H2O)1, 2 or 4
S.M. Ben-saber et al. / Microchemical Journal 81 (2005) 191 – 194
193
Table 2 Infrared and electronic absorption spectra of the Schiff base and its complexes Ligand/complex
IR (cm
1
)
UV – Vis [nm (cm
m CfN
m CfO
m OHw
d (OH)
m C – OH
mM – O
LH
1625
1690
–
1350
850
–
[FeL(OH)2(H2O)2] U 2H2O
1594
1656
3438
–
–
656 (430)
[CoL(OH)(H2O)] U H2O [NiL(OH)(H2O)] U 4H2O [ZnL(OH)(H2O)] U 2H2O
1595 1593 1593
1650 1671 1762
3438 3400 3422
– – –
– – –
680 (450) 656 (463) 640 (500)
1
)]
(M – N)
234 307 540 620 620 335 540
(42,735) (32,573) (15,815) (16,129) (16,129) (29,806) (15,815)
LH = free Schiff base. IR = infrared. UV – Vis = ultraviolet – visible.
3.1. Elemental analysis The elemental analysis data of the Schiff base and its complexes are given in Table 1. The data show the formation of 1:1 [M:L] ratio of the formulae of [M(Imine) (OH)x (H2O)y ] I nH2O, where M represents Fe(III), Co(II), Ni(II) and Zn(II) ions, while Imine represents the deprotonated Schiff base, x(OH) = 1 or 2, y(H2O) = 1 and n = 1,2 or 4. We found that the theoretical values are in a good agreement with the found values. The purity of the Schiff base and its complexes were assured by the elemental analyses and TLC techniques. 3.2. Molar conductance measurements The molar conductance values of the synthesized complexes with the mentioned metal ions under investigation were determined using 1 10 3M DMF solution, as shown in Table 1, are in the range of 3.40– 10.1 V 1 cm 2 mol 1. These values suggest the presence of a non-electrolytic nature in the same solvents [6]. Also these values indicate that there are no anions existing in the outer sphere coordination. 3.3. Infrared spectra The infrared spectrum of the Schiff base exhibits a band at 1625 cm 1 assignable to m (CfN) of the azomethine. This band shifts to lower region by about 33 cm 1 on the chelation with metal ions listed in Table 2. The infrared spectral data of all metal complexes exhibit a band at 1656– 1671 cm 1, indicating the presence of CfO group of the carboxyl group in ortho-position in the ring. This band appeared in lower frequency compared by the original position in free ligand which is 1690 cm 1. The band of OH group of carboxyl group at 2500 – 3400 cm 1 in the free ligand has been disappeared on chelation [7]. The spectra of the complexes show a broad band around 3400– 3438 cm 1 attributed to the existence of coordinated and hydrated water molecules [8,9]. The spectra display the disappearance of d (OH) and m (C – OH) bands at 1350 cm 1 and 850 cm 1 respectively. The appearance of new bands at 430 – 500 cm 1 and 640 –680 cm 1, that attributed to m (M – N) and m (M – O) vibrations supporting the participation of the nitrogen atom of the azomethine group and oxygen atom of the of OH group of carboxyl group of the ligand in the complexation with metal ions [10,11]. There is no evidence that the nitrogen atom in the p-position of the benzaldehyde moiety is involved in coordination with metal ions [12]. 3.4. Electronic spectra The electronic spectra of the Schiff base and its complexes (Fig. 1) were recorded in chloroform and their assignments are given in Table 2. The free Schiff base spectral data exhibit bands at 334 and 307 nm (42,735 and 32,573 cm 1) due to the k – k* transitions. The absorption bands at 540 and 620 nm (18,518 and 16,129 cm 1) are ascribed to 2A1gY2T1g transition. The intensity of the absorption bands suggests an octahedral geometry for Fe(III)– Schiff base complex [13]. The electronic spectrum of 1:1 (M;L;) ratio of Co(II) – Schiff base complex of the type [Co(L) (OH) (H2O)] I H2O shows a band at 620 nm (16,129 cm 1) is assigned to a square planar geometry [14]. The Ni(II) – Schiff base complex spectrum displays absorption band at 335 nm (29,850 cm 1) owing 2B1gY2E1g transition and suggesting a square planar geometry [15]. The electronic spectrum of Zn(II) – Schiff base complex exhibits a MYL charge transfer band at 540 nm (18,518 cm 1). This complex presumably has a tetrahedral configuration [16].
194
S.M. Ben-saber et al. / Microchemical Journal 81 (2005) 191 – 194
N(CH3)2
4. Conclusion
N(CH3)2
H
From the previous data; elemental analysis, molar conductance measurements, infrared and electronic spectra of the metal ion complexes, the following can be drawn concerning the ligating property of the Schiff base as well as the stereochemistry of their corresponding
H H2O OH
N
.2H2O
OH
N
Fe OH
O O
Co
.H2O
OH2
O O
H2O
N(CH3)2
N(CH3)2
H
H OH
N
N
.4H 2O
Ni O O
OH
.2H 2O
Zn O
OH2
OH
O
Fig. 2. The proposed chemical structures of the complexes.
complexes. The molar conductance measurements of the complexes show the non-electrolytic nature. The infrared spectral data reveal one mode of complexation through nitrogen atom of azomethine group and oxygen atom of hydroxyl group of the carboxyl group in o-aminobenzoic acid. The electronic spectra exhibit three kinds of geometries; square planar for Co(II) and Ni(II) complexes, tetrahedral for Zn(II) complex and octahedral for Fe(III) complex. The suggested structural formulae of the metal – Schiff base complexes under investigation are given in Fig. 2.
References
Fig. 1. Electronic absorption spectra of Fe(III), Co(II), Ni(II) and Zn(II) chelates with L2.
[1] A. Kumar, G. Sigh, R.R. Handa, S.N. Duhey, P.J. Squattroto, Indian J. Chem., Sect. A 38 (1999) 613. [2] R.K. Shikkargol, S.D. Angadi, V.H. Kulkarni, Orient. J. Chem. 1 (1996) 172. [3] M.D. Boghaei, S.J.S. Sabounchei, S. Rayati, Synth. React. Inorg. Met. Org. Chem. 30 (8) (2000) 1535. [4] A.A. Maihub, M.M. El-ajaily, S.M. Filog, Preparation and spectroscopic investigation of some Schiff base complexes of divalent transition metal ions, Asian J. Chem. 17 (2005). [5] A.A. Maihub, M.M. El-ajaily, S.S. Hudere, Experimental studies on some Schiff base complexes, Asian J. Chem. 17 (2005). [6] N. Raman, Y.P. Raja, A. Kulandaisory, Indian Acad. Sci. 113 (3) (2001) 183. [7] L.J. Bellamy, Infrared Spectra of Complex Molecules, Chapman and Hall Ltd, London, 1975. [8] M.D. Boghaei, M. Lashanizadagan, Synth. React. Inorg. Met.-Org. Chem. 30 (2000) 1393. [9] A.M. El-Roudi, Fac. Sci., vol. 18 (2), Assiut University, 1989, p. 77. [10] B. Singh, B.N. Banaree, A.K. Dey, J. Indian Chem. Soc. 57 (1980) 365. [11] J.R. Ferraro, Low Frequency Vibration of Inorganic and Coordination Compounds, Plenum Press, New York, 1971. [12] A.M.A. Hassan, J. Islam. Acad. Sci. 4 (4) (1991) 271. [13] W.L. Jolly, Principle of Inorganic Chemistry, McGraw-Hill, London, 1976, p. 272. [14] C. Spinu, A. Kriza, Act. Chem. Solv. 47 (2000) 179. [15] H.B. Gray, R.L. Cartin (Eds.), Transition Metal Chemistry, vol. 1, Marcel Dekker, New York, 1995, p. 239. [16] D.C. Sulikowska, A. Malinowska, Pol. J. Chem. 76 (2002) 1047.
Complexation behavior of Schiff base toward transition metal ions S.M. Ben-sabera, A.A. Maihubb, S.S. Huderec, M.M. El-ajailyd,* a
Pharmaceutical Chem. Department, Faculty of Pharmacy, Gar-Younis University, Benghazi, Libya b Chemistry Department, Faculty of Science, Al-Fateh University, Tripoli, Libya c The Man Great River Project (GMRUA), Libya d Chemistry Department, Faculty of Science, Gar-Younis University, Benghazi, Libya Received 21 April 2004; received in revised form 26 February 2005; accepted 1 March 2005 Available online 26 May 2005
Abstract Complexes of Iron, Cobalt, Nickel and Zinc ions with the Schiff base derived from p-dimethylaminobenzaldehyde and o-aminobenzoic acid were synthesized and investigated by several techniques using elemental analyse (C,H,N), molar conductance measurements, infrared and electronic spectra. The elemental analysis data suggest the stoichiometry to be 1:1 [M:L] ratio formation. The molar conductance measurements reveal the presence of non-electrolytic nature complexes. Infrared spectral data agreed with the coordination to the central metal ions through both the nitrogen atom of the azomethine and oxygen atom of the carboxyl group of the 2-aminobenzoic acid moiety. The electronic spectral data suggest the existence of octahedral geometry for Fe(III) complex, square planar geometry for Co(II) and Ni(II) complexes and tetrahedral geometry for Zn(II) complex. D 2005 Elsevier B.V. All rights reserved. Keywords: Complexation behavior; Schiff base; Transition metal ions
1. Introduction Complexes of various metal ions with Schiff bases derived from 3-aminomethyl-4-amino-5-mercapto-1,2,4-triazole and thiocarbohydrazones have been extensively studied [1]. There is growing interest in the studies on meal complexes of Schiff bases derived from triazoles which are biologically important ligands [2]. The unsymmetrical Schiff base such as 1-hydroxy2-acetonaphthoneacetylacetoneethylenediamine and its complexes with some transition metal ions have been prepared and investigated by different techniques [3]. The complexes of Co(II), Ni(II) and Cu(II) ions with the Schiff bases derived from the condensation of salicylaldehyde and o-aminophenol or 2-aminobenzoic acid were synthesized and characterized by using different techniques; in particular the elemental analysis, molar conductance measurements, infrared and electronic spectra. The square planar geometry for all metal complexes were suggested [4,5].
As a continuation of our previous work on ‘‘The experimental studies on some Schiff bases complexes’’, we are reporting here the complexation behavior of Schiff base derived from the condensation of p-dimethylaminobenzaldehyde and o-aminobenzoic acid with Fe(III), Co(II), Ni(II) and Zn(II) ions.
2. Experimental 2.1. Solvents and reagents All chemicals used in this investigation were laboratory pure including FeCl3 I 6H2O, CoCl2 I 6H2O, NiCl2 I 6H2O, ZnCl2, NH4OH, C2H5OH, DMSO, DMF, CHCl3, pdimethylaminobenzaldehyde and o-aminobenzoic acid and double distilled Water. 2.2. Physical measurements
* Corresponding author. E-mail address: [email protected] (M.M. El-ajaily). 0026-265X/$ - see front matter D 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.microc.2005.03.001
The elemental analyses of C, H and N were performed in advanced laboratory of chemical analysis, Al-
192
S.M. Ben-saber et al. / Microchemical Journal 81 (2005) 191 – 194
Table 1 Elemental analysis and molar conductances of the Schiff base and its complexes Ligand/complex
Molecular weight
%C Calculated
Found
Calculated
Found
Calculated
Found
LH [FeL(OH)2(H2O)2] I 2H2O [CoL(OH)(H2O)] I H2O [NiL(OH)(H2O)] I 4H2O [ZnL(OH)(H2O)] I 2H2O
268 429 379 432.7 422.40
71.64 44.75 50.65 44.37 47.49
71.70 44.83 50.29 43.64 46.48
5.97 5.82 5.27 6.00 5.33
5.20 5.20 4.60 6.81 5.25
10.44 6.53 7.38 6.47 6.93
10.33 7.34 8.38 7.18 7.80
LH = free Schiff base. MC = molar conductivity (V
1
cm2 mol
%H
%N
MC
– 3.40 5.20 7.90 10.1
1
).
Fateh University, Tripoli, Libya. The molar conductance measurements carried out in DMF solvent using conductivity meter model CMD650 digital meter. Infrared spectra were recorded using KBr disc technique on IFS-25DPUS/IR spectrometer (Bruker). The electronic absorption spectra were measured by using a PerkinElmer lambda 4h spectrophotometer in 1 cm matched silica cells. 2.3. Preparation of Schiff base The Schiff base used was prepared by mixing an ethanolic solution (50 ml) of 1.49 g (0.01 mol) of pdimethylaminobenzaldehyde with 1.37 g (0.01 mol) of oaminobenzoic acid in the same volume of ethanol. The mixture then refluxed with stirring for 2 h. The precipitate was collected by filtration through Buchnner funnel, recrystallized from ethanol, and dried at room temperature with 85% yield.
2.4. Preparation of complexes The Schiff base complexes under investigation were prepared by mixing 25 ml ethanolic solution of the Schiff base (0.01 mol; 2.86 g) with 25 ml of the ethanolic solution of the metal salts (0.01 mol); FeCl3 I 6H2O (2.80 g) CoCl 2 I 6H 2 O (2.38 g), NiCl 2 I 6H 2 O (2.37 g), ZnCl2(1.36 g). If the solid complexes did not separate, few drops of NH4OH solution were added to adjust the pH = 6 –8. The obtained mixture was refluxed with stirring for 2 h, and then kept overnight to insure the complete reactions. Thus, the formed complexes were filtered, collected and then washed several times with hot ethanol until the filtrate becomes colorless. The complexes were dried in a desiccator over anhydrous calcium chloride under vacuum. The yield ranged from 70% to 80%. The complexes are insoluble in CH3OH and CH3CH2OH but soluble in CHCl3 and DMF. The dried complexes were subjected to elemental and spectroscopic analyses.
3. Results and discussion The condensation of p-dimethylaminobenzaldehyde with o-aminobenzoic acid in boiling ethanol yields one Schiff base compound. The chemical equations concerning the formation of the Schiff base and the complexes represented as follows:
H NH2 +
O N O
OH
H N
H Mn+
N
N(CH3)2 NH4OH
O
O
N(CH3)2
N(CH3)2
OH
O
H
O
O
N(CH3)2 .nH2O
M(OH)1 or 2 (H2O)1, 2 or 4
S.M. Ben-saber et al. / Microchemical Journal 81 (2005) 191 – 194
193
Table 2 Infrared and electronic absorption spectra of the Schiff base and its complexes Ligand/complex
IR (cm
1
)
UV – Vis [nm (cm
m CfN
m CfO
m OHw
d (OH)
m C – OH
mM – O
LH
1625
1690
–
1350
850
–
[FeL(OH)2(H2O)2] U 2H2O
1594
1656
3438
–
–
656 (430)
[CoL(OH)(H2O)] U H2O [NiL(OH)(H2O)] U 4H2O [ZnL(OH)(H2O)] U 2H2O
1595 1593 1593
1650 1671 1762
3438 3400 3422
– – –
– – –
680 (450) 656 (463) 640 (500)
1
)]
(M – N)
234 307 540 620 620 335 540
(42,735) (32,573) (15,815) (16,129) (16,129) (29,806) (15,815)
LH = free Schiff base. IR = infrared. UV – Vis = ultraviolet – visible.
3.1. Elemental analysis The elemental analysis data of the Schiff base and its complexes are given in Table 1. The data show the formation of 1:1 [M:L] ratio of the formulae of [M(Imine) (OH)x (H2O)y ] I nH2O, where M represents Fe(III), Co(II), Ni(II) and Zn(II) ions, while Imine represents the deprotonated Schiff base, x(OH) = 1 or 2, y(H2O) = 1 and n = 1,2 or 4. We found that the theoretical values are in a good agreement with the found values. The purity of the Schiff base and its complexes were assured by the elemental analyses and TLC techniques. 3.2. Molar conductance measurements The molar conductance values of the synthesized complexes with the mentioned metal ions under investigation were determined using 1 10 3M DMF solution, as shown in Table 1, are in the range of 3.40– 10.1 V 1 cm 2 mol 1. These values suggest the presence of a non-electrolytic nature in the same solvents [6]. Also these values indicate that there are no anions existing in the outer sphere coordination. 3.3. Infrared spectra The infrared spectrum of the Schiff base exhibits a band at 1625 cm 1 assignable to m (CfN) of the azomethine. This band shifts to lower region by about 33 cm 1 on the chelation with metal ions listed in Table 2. The infrared spectral data of all metal complexes exhibit a band at 1656– 1671 cm 1, indicating the presence of CfO group of the carboxyl group in ortho-position in the ring. This band appeared in lower frequency compared by the original position in free ligand which is 1690 cm 1. The band of OH group of carboxyl group at 2500 – 3400 cm 1 in the free ligand has been disappeared on chelation [7]. The spectra of the complexes show a broad band around 3400– 3438 cm 1 attributed to the existence of coordinated and hydrated water molecules [8,9]. The spectra display the disappearance of d (OH) and m (C – OH) bands at 1350 cm 1 and 850 cm 1 respectively. The appearance of new bands at 430 – 500 cm 1 and 640 –680 cm 1, that attributed to m (M – N) and m (M – O) vibrations supporting the participation of the nitrogen atom of the azomethine group and oxygen atom of the of OH group of carboxyl group of the ligand in the complexation with metal ions [10,11]. There is no evidence that the nitrogen atom in the p-position of the benzaldehyde moiety is involved in coordination with metal ions [12]. 3.4. Electronic spectra The electronic spectra of the Schiff base and its complexes (Fig. 1) were recorded in chloroform and their assignments are given in Table 2. The free Schiff base spectral data exhibit bands at 334 and 307 nm (42,735 and 32,573 cm 1) due to the k – k* transitions. The absorption bands at 540 and 620 nm (18,518 and 16,129 cm 1) are ascribed to 2A1gY2T1g transition. The intensity of the absorption bands suggests an octahedral geometry for Fe(III)– Schiff base complex [13]. The electronic spectrum of 1:1 (M;L;) ratio of Co(II) – Schiff base complex of the type [Co(L) (OH) (H2O)] I H2O shows a band at 620 nm (16,129 cm 1) is assigned to a square planar geometry [14]. The Ni(II) – Schiff base complex spectrum displays absorption band at 335 nm (29,850 cm 1) owing 2B1gY2E1g transition and suggesting a square planar geometry [15]. The electronic spectrum of Zn(II) – Schiff base complex exhibits a MYL charge transfer band at 540 nm (18,518 cm 1). This complex presumably has a tetrahedral configuration [16].
194
S.M. Ben-saber et al. / Microchemical Journal 81 (2005) 191 – 194
N(CH3)2
4. Conclusion
N(CH3)2
H
From the previous data; elemental analysis, molar conductance measurements, infrared and electronic spectra of the metal ion complexes, the following can be drawn concerning the ligating property of the Schiff base as well as the stereochemistry of their corresponding
H H2O OH
N
.2H2O
OH
N
Fe OH
O O
Co
.H2O
OH2
O O
H2O
N(CH3)2
N(CH3)2
H
H OH
N
N
.4H 2O
Ni O O
OH
.2H 2O
Zn O
OH2
OH
O
Fig. 2. The proposed chemical structures of the complexes.
complexes. The molar conductance measurements of the complexes show the non-electrolytic nature. The infrared spectral data reveal one mode of complexation through nitrogen atom of azomethine group and oxygen atom of hydroxyl group of the carboxyl group in o-aminobenzoic acid. The electronic spectra exhibit three kinds of geometries; square planar for Co(II) and Ni(II) complexes, tetrahedral for Zn(II) complex and octahedral for Fe(III) complex. The suggested structural formulae of the metal – Schiff base complexes under investigation are given in Fig. 2.
References
Fig. 1. Electronic absorption spectra of Fe(III), Co(II), Ni(II) and Zn(II) chelates with L2.
[1] A. Kumar, G. Sigh, R.R. Handa, S.N. Duhey, P.J. Squattroto, Indian J. Chem., Sect. A 38 (1999) 613. [2] R.K. Shikkargol, S.D. Angadi, V.H. Kulkarni, Orient. J. Chem. 1 (1996) 172. [3] M.D. Boghaei, S.J.S. Sabounchei, S. Rayati, Synth. React. Inorg. Met. Org. Chem. 30 (8) (2000) 1535. [4] A.A. Maihub, M.M. El-ajaily, S.M. Filog, Preparation and spectroscopic investigation of some Schiff base complexes of divalent transition metal ions, Asian J. Chem. 17 (2005). [5] A.A. Maihub, M.M. El-ajaily, S.S. Hudere, Experimental studies on some Schiff base complexes, Asian J. Chem. 17 (2005). [6] N. Raman, Y.P. Raja, A. Kulandaisory, Indian Acad. Sci. 113 (3) (2001) 183. [7] L.J. Bellamy, Infrared Spectra of Complex Molecules, Chapman and Hall Ltd, London, 1975. [8] M.D. Boghaei, M. Lashanizadagan, Synth. React. Inorg. Met.-Org. Chem. 30 (2000) 1393. [9] A.M. El-Roudi, Fac. Sci., vol. 18 (2), Assiut University, 1989, p. 77. [10] B. Singh, B.N. Banaree, A.K. Dey, J. Indian Chem. Soc. 57 (1980) 365. [11] J.R. Ferraro, Low Frequency Vibration of Inorganic and Coordination Compounds, Plenum Press, New York, 1971. [12] A.M.A. Hassan, J. Islam. Acad. Sci. 4 (4) (1991) 271. [13] W.L. Jolly, Principle of Inorganic Chemistry, McGraw-Hill, London, 1976, p. 272. [14] C. Spinu, A. Kriza, Act. Chem. Solv. 47 (2000) 179. [15] H.B. Gray, R.L. Cartin (Eds.), Transition Metal Chemistry, vol. 1, Marcel Dekker, New York, 1995, p. 239. [16] D.C. Sulikowska, A. Malinowska, Pol. J. Chem. 76 (2002) 1047.