Research Journal of Chemical Sciences ______________________________________________ ISSN 2231-606X Vol. 4(8), 25-32, August (2014) Res. J. Chem. Sci. International Science Congress Association 25 Schiff Base Complexes of Fe (III) Derived from Amino AcidsAl-Shaheen J. Amira Al-Mula A. Miaa Department Chemistry, Education of College, University of Mosul, Mosul, IRAQAvailable online at: www.isca.in, www.isca.me Received 28th May 2014, revised 7th June 2014, accepted 16th August 2014 Abstract Schiff bases derived from vanillin and amino acids (glycine, L-serine, L-tyrosine and L-phenylalanine) and their complexes with Fe(III)have been prepared and characterized by many physicochemical methods such as elemental analysis (CHN), magnetic susceptibility, molar conductance as well as spectral studies such as IR and UV-Visible. The analytical data showed that the complexes having four and six coordination number with the following formulas [Fe(VA)(HO)Cl], [Fe(VA)(CHCOO)(OH)], where A=serine or tyrosine [Fe(Vg)(CHCOO)(OH)], [Fe(VA*H(HO)(NO](NOand[Fe(VA*)(HO)(NO], A* =all the amino acids .The ligands behave as tetradentatecoordinating through the atoms NOOO, or tridentate NOO; where V= vanillin, A= amino acids (glycine and phenylalanine). Keywords: Schiffbase complexes, Fe (III) complexes, amino acid complexes. Introduction Recent years witness a growing interest in the chemistry of iron (III) complexes which serve as models for biological systems1-3. Recently, considerable attention has been paid to the chemistry of metal complexes of amino acids of Schiff bases containing oxygen, nitrogen and other donors for their physiological reasons4-6, since amino acids are absorbed well from intestinal lumen by specific active transport mechanisms, amino acids containing imines display significant biologically8-10, they easily form stable complexes with most transition metal ions11-13. According, we report herein synthesis and characterization of some new complexes of Fe(III) with N,O donor Schiff base derived from vanillin with some aminoacids, and they characterized by different chemical, physical and spectral methods. Experimental: Chemicals: All chemicals and solvents used were of analytical grade .The metal salts were commercially available pure samples. They included iron (III) chloride, (Aldrich), iron (III) acetate (Fluka), iron(III) nitrate (Bisolve), vanillin (B.D.H). Material and Methods Melting point and decomposition temperature were determined using SMP30 melting point apparatus.IR spectra measurements were recorded using FTIR-Tensor 27-Burker co. Germany 2003 as KBr pellets in the range (400-4000 cm-1). UV-visible spectral measurements were done on Shimaduz 1800 spectrophotomer for 10-3 M complexes in DMF solvent at room temp using 1cm quarts cell in range (190-1100) nm. microanalysis (C, H, N) were performed using Caltech instrumental elemental Combustion. Molar conductance of complexes were measured at room temp for 10-3M in DMF using Multiline F-SET-2WTW Wissenschaf Technische Werktattem 82362 Weicheim. Magnetic susceptibility of the complexes was measured by Bruker –BM6. Iron contents were determined by apply ingatomic absorption using sense AAGB Scientific Equip men, after the decomposition of the complexes with concentrated nitric acid. Synthetic methods: 1-Preparation of the Schiff base salts(ligands), Sodium vanillin amino acids imine: Equal amounts ofamino acids 0.01mol (1.05g of L- serine or 1.65g of L-phenylalanine or 0.77g of glycine or 1.81g of L-tyrosine) in 20ml (25% distilled water + 75% ethanol) was mixed with vanillin (1.5g, 0.01mol) in 20ml ethanol in presence of sodium acetate (0.82g,0.01mol). The mixture was heated at 50°C in water bath for an hour, the mixture was cooled and measured the pH. Then the solution was evaporated about its half volume and left for overnight to complete precipitation, the precipitate was collected by filtration, washed with 1:1 ethanol –water mixture and diethylether and it was dried over anhydrous over anhydrous CaCl. The analytical data for C.H.N and % yield (table 1 and 2). Preparation of the complexes: i. Preparation of iron (III) chloride complexes: 0.01mol of Schiff base salt in 20 ml ethanol has been added to 0.01 moliron (III) chloride in 10ml of hot ethanolic solution, followed by slow addition of aqueous solution of sodium acetate (0.02 mol). The mixture has been refluxed for half an hour at 50c with stirring, followed by cooling, and measuring the pH, then evaporated to half its volume, cooled, filtered, washed with ether and dried over CaCl2. ii. Preparation of iron (III) acetate: By following above procedure in A expect without addition of sodium acetate and refluxing time 2 hours. iii. preparation of iron (III) nitrate: A general procedure has been adopted for the preparation of Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 4(8), 25-32, August (2014) Res. J. Chem. Sci. International Science Congress Association 26 complexes in neutral and basic medium. In neutral medium, a solution of 0.01mol of each of amino acids and vanillin in20 ml (25% distilled water +75% ethanol) has been added to the solution of iron (III) nitrate (0.01mol), the mixture has been refluxed for an half hour at 50°C with stirring, followed by cooling and measuring the pH, The product has been filtered off, washed with ether and dried over CaCl. In basic medium, complexes have been prepared by applying the same amount used in neutral medium, and after mixing the iron nitrate with ligands and heating on a water bath, sodium hydroxide solution (1M) has been added until pH (9-12), then followed above steps as in neutral medium. Table-1 Names, Structures and Abbreviations of Schiff Base Ligands Schiff base compound Structure Abbreviation Sodiumvanillinserine imine CHCOONa O C H 3CH 2 OHHONaVs Sodiumvanillinglycine imine C NH CHCOONaOCHHO NaVg Sodiumvanillintyrosine imine CH O C H HOCONaCHOHNaVt Sodiumvanillinphenylalanineimine C NH CHOCHHO CONaCH NaVphe Table-2 Some physical properties of Schiff Base Ligands No. Abbrev. Chemical formula Color Cº m.p or d Yield (%) % Analysis, Calc. (Observ.) C H N 1 NaVs C1112 NONa yellow 83 80 50.57 (50.41) 4.59 (4.45) 5.36 (5.22) 2 NaVg C1010 NONa Yellow7585 51.94 (51.82) 4.32 (4.19 ) 6.06 (5.90) 3 NaVt C1716 NONa Pale yellow 197 75 60.53 (60.47) 4.74 (4.80) 4..15 (4.02) 4 NaVphe C1716 NONa Dark yellow 112 69 63.35 (63.20) 4.98 (4.80) 4.36 (4.25) Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 4(8), 25-32, August (2014) Res. J. Chem. Sci. International Science Congress Association 27 Results and Discussion The reaction of iron salts with Schiff bases can be represented by the following reactions. The solid complexes are coloured, insoluble in water, methanol and ethanol but soluble in DMF at 10-3M (table 3) revealed that complexes (1-5,10-13 ) are non electrolytic indicating neutral complexes, while complexes (6-9) are 1:4 electrolyte in nature for nitrate complexes in neutral medium14.The molars conductance values and the metal contents are in a good agreement with given formulations. Table-3 Analytical data and physical properties of the complexes No. Complexes m.p or d Color LLmmeff.% Analysis Calc. (Observ.) C H N M 1. [Fe(Vg)(HO)Cl] 95 brown 15 5.7 35.92 (35.79) 3.58 (3.56) 4.17 (4.08) 16.65 (16.76) 2. [Fe(Vphe)(HO)Cl] 82 brown 19 6.0 47.96 (46.92) 4.23 (4.16) 3.29 (3.15) 13.13 (13.09) 3. [Fe(VS)(CHCO)(OH)] 122 brown 21 5.7 30.95 (30.75) 3.50 (3.56) 2.57 (2.72) 20.58 (20.70) 4. [Fe(VT)(CHCO)(OH)] 197d brown 12 5.9 43.95 (44.11) 3.66 (3.81) 2.69 (2.84) 21.53 (21.72) 5. [Fe(Vg)(CHCO)(OH)] 224 brown 16 5.8 33.51 (33.81) 4.18 (4.32) 3.25 (3.30) 25.99 (25.78) 6. [Fe(VgH(HO)(NO](NO 328d brown 295 4.9 19.73 (19.85) 2.19 (2.23) 13.43 (13.61 15.30 (15.66) 7. [Fe(VpheH(HO)(NO](NO 328d brown 295 4,2 26.92 (2672) 2.90 (3.11) 12.93 (12.80 14..74 (14.91) 8. [Fe(VSH(HO)(NO](NO 276 brown 300 4.1 26.45 (26.30) 2.60 (2.48) 5.61 (5.50) 11.11 (11.22) 9. [Fe(VTH(HO)(NO](NO 300d brown 310 4.3 26.36 (26.42) 2.84 (2.69) 12.66 (12.23 14.43(14.58) 10. [Fe(Vg)(HO)(NO] 282 brown 11 49 32.78 (32.92) 3.27 (3.34) 7.65 (7.87) 16.40 (1632) 11. [Fe(Vphe)(HO)(NO] 198d brown 10 4.3 46.04 (45.71) 3.38 (3.12) 6.32 (6.25) 12.74 (12.64) 12 [Fe(VS)(HO)(NO] 285 brown 12 5.0 35.38 (35.13) 2.94 (2.62) 7.50 (7.25) 14.90 (15.01) 13 [Fe(VT)(HO)(NO] 320d brown 18 2.3 45.54 (45.31) 3.34 (3.22) 6.23 (5.97) 12.40 (12.47) d= decomposition point = molar conductivities in -1 cmmol–1 Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 4(8), 25-32, August (2014) Res. J. Chem. Sci. International Science Congress Association 28 IR Spectra: The coordination sites of the ligands involved in the bonding with metal ions had been determined by careful comparison of the (table 4 and 5) infrared spectra of those compounds with that of the parent ligands. The ligands basically composed of different groups of potent ability to coordinate with the metal ions. The IR spectra of the Schiff bases showed a strong band in the region (1672-1650) cm-1, which is characteristic of the azomethane (stretching frequency C=N) group. In all complexes, this band is slightly shifted to lower frequency indicating coordination of the Schiff bases through azomethine nitrogen atom15,16. The IR spectrum of the ligands exhibit a broad band of stretching frequency of phenolic(OH) groupat (3369-3443) cm-1 (the broadness due to the presence of hydrogen bonding) and a second band at (1371-1300) cm-1due to bending phenolic OH group, these two bands are absent in the complexes due to deprotonation on coordination to the metal ion, and shifted toward a lower frequency on coordination for complexes that have been prepared in neutral medium. Also, two new bands were observed in region3240-3245and1235-1342cm-1due to the stretching and bending respectively, of hydroxyl group for complexes 3-5. In addition, the stretching vibration of C-O single band split in to two peaks support the above suggested coordination of the hydroxyl group of the amino acid moiety without deprotonation17. Another important strong band observed in the spectrum of the free ligand ascribed to phenolic stretching (C-O)group at (1245-1267) cmis shifted to lower frequency in all complexes. This is usually indicates that the (C-O) group of the ligand involved in coordination with the metal ion through the deprotonated oxygen of phenolic group18. The ligands exhibit other two intense bands at (1411-1334), (1590-1585)cm-1 corresponding to symmetric and asymmetric stretching frequencies of (COOH)group, respectively of the organic ligand and of the acetate group. On complexation symmetric bands were shifted to a higher frequencies or remained unaltered in the position of the ligands, while asymmetric bands were shifted to ward a lower frequencies respectively19. The difference between the symmetry and asymmetry stretching vibration of COOgroup  which is equal to 150-160 cm-1) gave indication about the manner of coordination of carboxylic group, this value showed that amino acid Schiff bases coordinated through COOgroup which was acted as monodentate20. The acetate complexes exhibited bands differences as bidentate chelating aceta to group and confirmed by electronic spectra of the complexes19. The presence of (COO) group makes the coordination phenomenon is more complicated due to presence of acetato group belongs to metal. The C-O stretching vibration of the free acetate ion was observed at 1600 cm-1 and shifted to lower frequency that is conformity with many authors20. The IR spectra of nitrato complexes display three (N-O) stretching bands. The infrared data indicated the occurrence of two strong absorption bands in1470-1424 cm-1, 1290-1234 cm-1and 950 cm-1 regions, which were attributed to (v,v1 and ) modes of vibrations of the covalently bonded nitrate groups, respectively15The (v-v) is taken as an approximate measure of the covalency of nitrate group15, a value of ~220 cm-1for the complexes suggested strong covalence for the metal-nitrate bonding. Authors have shown that the number and relative energies measure of the covalence of nitrate combination frequencies (v-v) in the infrared spectrum and may be used as an aid to distinguish the various coordination modes of thenitrato group and have suggested that bidentate coordination of the nitrato group involves a greater distortion from D3h symmetry thanunidentate coordination, therefore, bidentate nitrate groups should show a larger separation of (v-v). After an investigation of the spectra of a number of compounds showed that the separation for monodentate nitrate groups appeared to be 115 cm-1 and that for bidentate groups 220 cm-1. In the present complexes, a separation of190-180 cm-1, and the nitro groups seem to be bidentate. On the other hand, the spectra of 10-13complexes showed the presence of additional band at (1380-1385) cm-1 due to ionic nature ofnitratogroup15. The aqua complexes contain weak to medium a broad band at (3451-3205) cm-1due to stretching vibration OH of water19 and a sharp shoulder at (1513-1540) cm-1may be assigned to bending vibration of water. Water molecules are coordinated, confirmed by occurrence of additional strong and sharp band at (813-876) cm-1 due to OH rocking vibrations21. For all complexes new bands were observed at (410-518) and (524-590) cm-1, these bands assigned to the stretching modes of M-N and M-O, respectively22. The presence of these bands support the formation of the complexes under investigation figures. Electronic Spectra and magnetic moment: The spectrum of the ligands exhibited two bands in the UV intervals at (40650-40535) cm-1 and (30864 -30756 )cm-1, assigned to and n transitions respectively. The electronic spectral bands observed for the Fe(III) complexes (1-5)at 14880-14925cm- and 16339-16501cm-1 (table-6) may be attributed to the 6(G) and to theE(G),(G) double trespectively. The band at 18484-18691cm-1 may be due to the E transitions while the remaining one at 21551-21786 cm-1 may be due to F transition, and (30303-33333) cm-1(C.T). These bands are in conformity with a tetrahedral coordination for the iron (III) complexes22. The values of the magnetic moments of these complexes are in the range (5.7-6.0) B.M. which are comparable with the values reported for other tetrahedral iron(III) complexes22,23. In the case of iron (III) complexes (6-13), only sextet term of the dconfiguration octahedral geometry is theterm1g and does not split by the ligand field. Consequently, all the excited states have different spin multiplicity from the ground term and transition to them is forbidden. Many weak bands were observed and assigned as due to transition from1gto1g (G), 2g(G) andEg(G). and these three bands are observed in the region (9328-9900,10204-1103and 12106-14084) cm-1assignable to above mentioned transitions respectively. All these complexes also exhibit charge transfer bands at (30303-39525) cm-1 (C.T). The complexes (6-13) show magnetic moments at room temperature calculated from the corrected magnetic susceptibilities are in the range (4.1-5.0) B.M revealing the presence offiveunpaired electrons are present Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 4(8), 25-32, August (2014) Res. J. Chem. Sci. International Science Congress Association 29 in the complex molecule and indicating high spin octahedral iron (III) complexes24,25. Conclusion From the above discussion of various physicochemical and spectral studies, we conclude that the Schiff base ligands of glycine and phenyl alanine coordinated as tridentate through phenoxy oxygen, carboxy oxygen and azomethine nitrogen atoms, while the Schiff base ligands of serine and tyrosine coordinated as tetradentate through phenoxy oxygen, carboxy oxygen, azomethine nitrogen and alcoholic or phenoxy oxygenatoms. The ligands are used as stabilizer for dinuclearmetal complexes and according to the measurements and theoretical calculations the Fe(III)chloride or acetate complexes have tetrahedral geometries, while Fe(III)nitrate complexes have octahedral geometries around central metal ion, figure 1 and 2. Table-4 Important IR spectra bands cm-1of the ligands OthersOH R(HO) M-O M-NasCOOsCOO C-OC=NComp.No 3426, 8665875341502133912161606 3441, 8485244691502141012251561 OH 3240 O-H 1342550420 1512 1430 1200 1596 OH 3245 O-H 1335-525468 1500 1409 1206 1562 OH 3243 O-H 1339588522 1512 1411 1212 1608 1470, 1290,950,13803410, 860528432 1508 1421 1220 1601 1424,1234,950,13853400, 875525480 1510 1389 1242 1582 1463,1270,950,13803480, 838590420 1500 1431 1200 1590 1455,1245,950,13853446, 820528424 1508 1403 1200 1593 ionic NO,13853214, 810586434 1509 1420 1234 1570 10 ionic NO13803220, 865543502 1510 1410 1233 1585 11 ionic NO,13803300, 835543474 1500 1425 1235 1582 12 ionicNO,13853442, 814529524 1502 1445 1224 1582 13 Table-5 Important IR spectral bands (cm-1) of the complexes O-H as(COO)- s(COO) O-H C-O C=N Ligand 337715881430137112661665NaVg 344315791411133912461672NaVphe 3369 1590 1434 1300 1245 1650 NaVS 3440 1585 1429 1338 1267 1665 NaVT Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 4(8), 25-32, August (2014) Res. J. Chem. Sci. International Science Congress Association 30 [Fe(VL)(HO)Cl], L=glycine or phenylalanine CO O MnOH 2 CHMn 2 CHCH[Fe(VA)(CHCO)(OH)], A= serine or Tyrosine [Fe(Vg)( CHCO)(OH)] g = glycine Figure-1 Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 4(8), 25-32, August (2014) Res. J. Chem. Sci. International Science Congress Association 31 FeOH O N O O OH N CH R C O O HO N Fe OH O NO OH C O CH R O (NO[Fe(Schiff base H)(HO)(NO](NOFeOH O N O O O N CH R C O O O N Fe OH O NO O C O CH R O [Fe(Schiff base)(HO)(NOFigure-2 Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 4(8), 25-32, August (2014) Res. J. Chem. Sci. 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