IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L.22 (4) 2009 Synthesis and Characterization of Novel Tetradentate ligand Type N4 and its Complexes With CoII,NiII,and PdII. E. I. Yousif Department of Chemistry, College of Education, Ibn Al-Haitham, University of Baghdad Abstract A new Schiff base ligand [2,3,8,9–tetra -phenyl-1,4,5,7,10,12-hexa azo-5,12- dihydro -6,11- dione 1,3,7,10-dudec-tetra-ene] [H2L] and its complexes In general formula [M(H2L)]Cl2 (where : M= CoII, NiII, and PdII) were prepared. This ligand was prepared in two steps,in the first step a solution of benzil in methanol was reacted under reflux with semicarbazidhydrochlorid to give an (intermediate compound)[benzyl bis–(Semicarbazone)] which was reacted in the second step with benzil giving the mentioned ligand. The complexes Co II, NiII, and PdII were synthesized by direct reaction of the corresponding metal chloride with the ligand [H2L].The ligand and complexes were characterized by spectroscopic methods (IR, UV-Vis, and atomic absorption), chloride content and conductivity measurement.From the data of these measurements, we suggestred a tetrahedral geometry for Co II, NiII complexs and a square planar for PdII complex. Introduction Schiff bases derived from condensation of semicarbazide with carbonyl compounds were reported as complexing agents for various transition metal ions. Many chemists have reported on the chemical structural and biological properties of Schiff bases. Schiff bases are characterized by the –N=CH-(imine) group which is very important in elucidating the mechanism of transmission rasemination reaction in some biological systems[1,2] . During the past two decades, considerable attention has been paid to the chemistry of metal complexes of Schiff bases containing nitrogen and other donor atoms[3,4].This may be attributed to their stability, biological activity [5]and potential application in many fields such as oxidatioin catalysis [6] and electrochemistry [7]. In 2006 kurup and Co-workers [8]reported that the reaction of 2- benzoyl pyridine N(4)-phenylthiosemicarbazone with variety of cupper salts yielded a series of cupper (II) complexes. The present paper reports the synthesis and characterization of new ligand [2,3,8,9-tetra-phenyl-1,4,5,7,10,12-hexa azo- 5,12-dihydro-6,11-dione-1,3,7,10-dudec-tetra-ene] [H2L] and its complexes with Co II, NiII and PdII. Experimental Reagents were purchased from Fluka and Rediel – Dehenge Chemical Co.I.R spectra were recorded as (KBr) disc by using a Shimadzu 8400 FTIR spectrophotometer in the range (4000-450) cm -1.Electronic spectra of the prepared compounds were measured in the region (200-1100) nm for 10 -3 M solution in (DM SO) at 25 0 C using a Shimadzu 160 spectrophotometer with 1.000±0.001 cm -1 matched quartz cell . Metal contents of the complexes were determined by atomic absorption (A.A) technique by using a Shimadzu A.A 680G atomic absorp tion spectrophotometer. The chloride contents for complexes were IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L.22 (4) 2009 determined by potentiometric titration method on (686-titro processor-665) ,Dosinat-metrom Swiss.Electrical conductivity measurements of the complexes were recorded at 250C for 10-3M solutions in (DMSO) as a solvent by using a PW 9526 digital conductivity meter. Synthesis of the ligand [H2L] The ligand was prepared in two steps. Step(1): Preparation of the [benzil bis -(Semicarbazone)] (intermediate compound). A solution of benzil (0.5g,2.37mmole) in methanol (5ml) was added to semicarbazidhydrochlorid (0.53g,2.37mmole) dissolving in methanol (5ml),and then(2-4) drops of glacial acetic acid were added slowly to the reaction mixture .The mixture was refluxed for 5 hours, and allowed to dry at room temperature for (24) hours. A white solid materal was obtained. Yield (89%),(0.69)g, m.p (215 0C). Step(2): Preparation of the [2,3,8,9-tetra-phenyl-1,4,5,7,10,12-hexa azo-5,12-dihydro- 6,11-dione-1,3,7,10-dudec-tetra-ene] [H2L]. A solution of [benzil bis-(Semicarbazone)](intermediatecompound)(0.5g,1.543 mmole) in methanol (5 ml) was added to benzil (0.32g, 1.543mmole) dissolving in methanol (5ml), then (2-4) drops of glacial acetic acid were added slowly to the reaction mixture .The reaction mixture was refluxed for (5) hours with stirring, filtered and the filtrate was allowed to dry at room temperature for (48) hours. Then , it was washed with (5)ml diethyl ether and dried at room temperature to give the white solid materal. Yield (77%), (0.59) g ,m.p (235 0 C). Synthesis of complexes All complexes were prepared by adding a dropwise of a solution of the ligand (H2L) (0.1g,0.2008mmole)in (5) ml methanol with stirring ,to 0.2008mmole of a solution of metal chloride salt MCl2.XH2O dissolved in(5) ml methanol ,where:[M=Co II ,Ni II and Pd II;X=6 for CoII,NiII and X=0 for PdII]. The reaction mixture was allowed to be refluxed for (2)hrs , let the coloury precipitate formed which was filtered,washed with (5) ml diethy l ether and dried at room temperature.Table(1)shows the stated weight of metal chloride salt ,% yield and some physica properties of the prepared complexes. Results and Discussion A-The ligand [H2L] The new ligand [H2L] was prepared in two steps according to the general method of preparation of Schiff base ligands [9] shown in scheme (1).The (I.R) spectrum for [H2L] (Fig. -2) , display a band at 3209 cm -1 which is due to the υ(N-H) stretching vibration [10]. The band at 1687 cm-1 is attributed to the υ(C=O) stretching vibration [11].The band at 1612 cm-1 is attributed to υ (C=N) stretching frequency for the imine group vibration [12-13],while the two bands at 1025 cm -1 and 935 cm-1 were attributed to the foramation of macrocycle [14] .And finaly , the band at 1062 cm-1 is attributed to (N-N) stretching vibration [15].The (U.V- Vis) spectrum(Fig.-3) exhibits a high intense absorption peak at (300 nm ) (33333 cm -1) ( εmax = 2128 molar-1.cm-1) which is assigned to overlap of (n →π*) electronic transitions [16]. IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L.22 (4)2009 O NH 2 N H C N OO N C H N H 2 N O O NH 3 Cl NH 2 NH C O N H N C p h N OO N C ph N H N O p h p h + (5) h o urs u n der r e fu l xe gl ac ia l a ce tic a cid (2- 4) dro p s B enz i l S em i ca rb az id h y d ro ch lor i d p h p h B en z il b is - se m i car b az o n e + p h p h B en z il (5) h ou rs u nd er r e fu lx e gl ac ia l a ce tic a cid (2- 4) d ro p s p h p h 2 Step (1 ) S tep (2) -2 H 2O Scheme (1) : Preparation of the ligand [H2L] B- Complexes of Co II , Ni II and Pd II with [H2L] The synthesis of the complexes was carried out by the reaction of [H2L] with [MCl2.XH2O] where M= [Co II ;X=6, Ni II ;X=6 and Pd II ;X=0] in methanol under reflux. These complexes are stable in solution and electrolyte (1:2) systems in (DM SO) (Table- 3).The analytical and physical data (Table-1) and spectral data (Table-3) are compatible with the suggested structures. The (I.R) spectra of complexes are presented in (Table-2). The (I.R) spectra of the complexes show a band at 1679 ,1675 and 1670 cm -1 which are due to υ(C=O) stretching vibration for complexes (1) , (2) and (3) respectively. These bands were shifted to a lower frequency in comparison with that of the free ligand at 1687 cm -1[17,18]. The strong band in free ligand [H2L] at 1612 cm-1 for the imine group υ (C=N) was shifted to a lower frequency and appeared at 1602,1605 and 1598 cm-1 for complexes (1),(2) and (3) respectively [12-14], showing a reducing in the bond order. This can be attributed to delocalization of metal electronic density at (t2g) in the π system of the ligand (HOMO → LUMO) [19]. Where HOM O = highest occupied molecular orbital. LUMO = lowest unoccupied molecular orbital. While the bands at 1074,1087 and 1085 cm -1 were assigned to υ (N-N) stretching vibration (15) in the complexes(1), (2) and (3) which were shifted to a higher frequency when it compared with free ligand. The appearance of the band at 698-507 cm -1 is due to υ(M-N) stretching .This suggests that the nitrogen of imine group was involved in coordination with the metal ion [20-23].Figs.(2a),(2b) and (2c) represent the (I.R) spectra of[Co (H2L)]Cl2, [Ni (H2L)]Cl2 and [Pd (H2L)]Cl2.The (U.V-Vis) spectra for the complexes (1), (2) and (3) are shown in Figs.(3a) ,(3b) and (3c). The absorption spectral data for complexes are given in (Table -3). The spectra show two intense peaks in the U.V region at (300,357), (300,361) and (300,371) nm for complexes (1), (2) and (3) respectively. These peaks were assigned to ligand field and charge transfer transition respectively (24).Complex (1) exhibited the peak at 609 nm which can be attributed to (d-d) electronic transition type (4A2→ 4T1(p)). The observed IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L.22 (4) 2009 peak in spectrum of complex (2) at 420 nm is assigned to (d-d) electronic transition type (3T1 → 3T2 ) . The spectrum of complexe (3) exhibited the very intense peak at 412 nm which can be attributed to (d-d) electronic transition type (1A1→ 1B1). These U.V-Vis data suggest a tetrahedral structure for CoII ,NiII complexes and a square planar for PdII complexe [25]. (Fig.- 1). The molar conductance values were determined in (DM SO) solution (10 -3 M) at 298 5 k were found in the range (72.03-79.11) Λm (Ω.cm 2.Mole-1) (Table-3) which indicated that the complexes are electrolytic in nature with 1:2 ratio for all complexes [26]. The atomic absorption analysis and the chloride content results of the complexes are in a good agreement with the suggested formula [M (H2L)]Cl2. C HN N ph N ph N C N NH ph ph C HN N ph N ph N C N NH ph ph M+MCl2.XH2O m ethanol ref luxe O O O O Cl 2 M=CoII, NiII and PdII Scheme (2) : Preparation of the metal complexes References 1. Lau ,K.Y.; Mayr, A.and Cheung, K .K (1999), “Synthesis of Transition Metal isocyanide complexes containing hydrogen bonding sits inperpheral locations,” , Inorg.Chim. .232-:223285,Acta 2. Shawali , A.S.; Harb, N.M .S.and Badahah ,K.O,(1985), “A study of tautonerism in -1397:22 ,.Chim.licHeterocyly.J ”,hydroxycoumrin -4diazonium coupling products of 1403. 3. Djebbar,S.S. ;Benali, B.O. and Deloume. J.P.,(1997),Synthesis,characterization and electrochemical behavior of copper(11)complexes with linear and tripodal 2182 - 2175:16, polyhedron. ses tetradentate ligand derived from Schiff ba 4. He. L .; Gou, S .H. and Shi, Q.F.(1999),The formation of a Schiff base intermediate :a - 207:29.Chystallogr . Chem.j.complexe of an asymmetric tripodal ligand )11(nickel 210. 5. Liu.C. M.; Xiong, R.G. ;You, X.Z. ;Liu, Y.J. and Cheung, K.K.,(1996), Crystal structure and some properties of a novel potent Cu2Zn2SOD model Schiff base copper (11) ).2006(61:15, polyhedron. complexe 6. Hamada ,Y.J.(1997) The development of chelate metal complexes as an organic IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L.22 (4) 2009 .1217-1208: 44,Electron Devices . Trans IEEE.electroluminescent material 7. Djebbar,S.S.; Benali,B.O. ;Deloume,j.p.,(1998),Synthesis,characterization and electrochemical behavior and catalytic activity of manganese (11)complexes with linear -443 :23. Chem.Metal.Transit.and tripodal tetradentate ligands derived from Schiff bases 447. 8. M.Joseph, M. ;Kuriakose, M.R.P.; Kurup, E. and Suresh, S.G. Bhat.(2006). polyhedron, 25:4565-4571. 9. Fedric Menger, M.; David, J.; Gold Smith and Leon Manden ,(1975),“ Organic chemistry” Aconicise approach ,2nd.,W.A.Benijamin, Inc.,P.318. 10. Marlin,D. S. and Mascharak, P. K. Chem. Soc. Rev., 29:69 (2000) 11. Parikh ,V.M. “Absorption spectroscopy of organic Molecules” Translated by Abdul Hussain Khuthier,jasimM.A.AL-Rawi,and Mahammed A.AL-Iraqi (1981). 12. Xishi Tai,Xianhong yin, Qiang chen,and Minyuta,(2003), “Synthesis of some Transition Metal complexes of a Novel Schiff Base ligand Derived from 2,2-Bis (P-Methoxy .440-439:8 , ”and Salicylicaldehyde Molecules amine phenyl 13. EL-Bindary, A.A.; AL-Shihri.A.S.; EL-Sonbouti, A.Z, (2003),Designed Monomers and polymers, 6(3): 283-298 . 14. Jakel,S.C.; Ciavola,J.; Carter,R.C. ;Cheek,P.L. and pascarelli,T.D. .3956:22,.chem.Inorg,)1983( 15. Collins.F.D. Nature,(1953),171:469. 16. Kemp.W. (1987 )“ Organic Spectroscopy” 2 nd .Ed., 144. 17.Pavel kopel, Martin Biler, Zdenek.Travnicek,and Milan Nadvorink ,(1998), “Iron( 111)Salen and Saloph Schiff bases bridged by dicaboxylic acids” chemical ,37. 18. Nakamoto, K. (1996) “Infrared Spectra of Inorganic and Coordination Compounds ” 4 th .Ed.,J.Wiely and Sons , New York 19. Pinchas, S. and Ben ,D. (1957)Ishai,j.Amer chem..Soc.79:4099,12. 20. Raju, K.C and Radhakrishnan, P.K, (2003). “Complexes of cupper with 2,3Dimethyl-4- fomyl(benzhydrazide) -1-phenyl-3-pyrazolin-5-one”, Synthesis and reactivity in inorganic andmetal-organic chemistry,33(8):1307-1318 21. EI.Tbleand A.S.; Kasher, T.I. ,(1998) polish j.chem. 72:519. 22. EL-Sonbati.A.Z. and EL-Bindary.A.A, (2000) “Stereo chemistry of New Nitrogen cantaining Aldehydes .V.Novel Synthesis and spectroscopic studies of some Quinoline Schiff Bases com plexes”,polish j.chem,74:621-630 23. Ferraro.J ,(1971). “Low Frquency Vibrations of Inorganic and Coordination Compounds ” Ed.Plenum,New York. 24. Green Wood, N.N and Earnshow,A , (1998) . “Chemistry of the Elements ” , Ed. J. Wiley and Sons Inc. New York ,. 25. Lever.A.B.L , (1968), “Inorganic Electronic Spectroscopy ” Ed. New York . 26. Geary. W.J , (1961) Coord .Rev., ,7:81 IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L.22 (4) 2009 C H N N p h N p h N C N N H p h p h M C l 2 O O M=CoII, NiII and PdII . . Fig (1): The suggested structure for the complexes Table(1): Some physical properties of the complexes and the weight of metal chloride salt. complexes decomposit ion temperature 0 C M.W Colour metal chloride Salt Weight of metal chloride(g ) =0.2008 mmole Weight of product g Yield % chloride content Metal ion % Prac. (Theo.) [Co (H2L] Cl2 295 627.8 3 pink CoCl2.6H 2O 0.04 0.11 87 Nill 8.11 (9.386) [Ni (H2L)] Cl2 270 627.5 9 green NiCl2.6H2 O 0.047 0.1 79 Nill 7.97 (9.351) [pd (H2L)] Cl2 255 675.3 Pale pink pd Cl2. 0.035 0.12 88 Nill 14.13 (15.755) IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L.22 (4) 2009 Table (2): I.R spectral data of the ligand and it’s complexes (cm-1). Othor bands υ (M- N) υ (N- N) υ (C=N) υ( C=O) υ (N- H) Compound υ ( C=C) 1444 υ (c-H) alph 2925 υ (C-H) arom 3047 - 1062 1612 1687 3209 [H2 L] υ (C=C) 1446 υ (c-H) alph 2898 3060υ (C-H) arom 613 698 1074 1602 1679 3217 [Co (H2L] Cl2 υ (C=C) 1431 υ (c-H) alph 2985 υ (C-H) arom 3053 603 636 1087 1605 1675 3220 [Ni (H2L)] Cl2 υ (C=C) 1442 υ (c-H) alph 2962 υ (C-H) arom 3074 507 557 1085 1598 1670 3215 [Pd (H2L)] Cl2 IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L.22 (4) 2009 Table (3) : Electronic spectral data , and conductance measurement for the ligand[H2L] and it’s complexes Compound λ nm Wave number Cm -1 εmax Molar-1 .Cm-1 Assignment Λm(Ω. cm 2.Mole -1) Propose structure [H2 L] 300 33333 2128 n →π* - - 300 33333 2111 Ligand field 357 28011 747 charge transfer [Co (H2L)] Cl2 609 16420 121 4 A2→ 4 T1(p) 77.55 tetrahedral 300 33333 2362 Ligand field 361 27700 870 charge transfer [Ni (H2L)] Cl2 420 23809 1846 3T1→ 3T2 79.11 tetrahedral 300 33333 2123 Ligand field 371 26954 915 charge transfe [Pd (H2L)] Cl2 412 24271 611 1A1→ 1B1 72.03 Square planar IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L.22 (4) 2009 Fig. (2) .The I.R. Spectrum of the ligand [H2L] Fig. (2a) .The I.R. Spectrum of the [Co (H2L)] Cl2 Fig. (2b) .The I.R. Spectrum of the [Ni (H2L)] Cl2 Fig. (2c) .The I.R. Spectrum of the [Pd (H2L)] Cl2 IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L.22 (4) 2009 Fig. (3) .The U.V. Spectrum of the ligand [H2L] Fig. (3a) .The U.V. Spectrum of the [Co (H2L)] Cl2 Fig. (3b) .The U.V. Spectrum of the [Ni (H2L)] Cl2 Fig. (3c) .The U.V. Spectrum of the [Pd (H2L)] Cl2 2009) 4 (22مجلة ابن الھیثم للعلوم الصرفة والتطبیقیة المجلد N4 جدیدسنتحضیر وتشخیص لیكاند رباعي ال نوع معهومعقدات CoII , NiII and PdII إنعام إسماعیل یوسف ابن الهیثم ، جامعة بغداد- قسم الكیمیاء ،كلیةالتربیة الخالصة تضمن البحث تحضیر اللیكاند الجدید[H2L] -:الذي یمثل [2,3,8,9-tetra-phenyl-1,4,5,7,10,12-hexaazo-5,12-dihydro-6,11-dione-1,3,7,10-dudec-tetra- ene] :طوتینخب semicarbazidhydrochlorid) ( معbenzil) ( الخطوة االولى مفاعلة [benzil bis -(Semicarbazone)] وینوتك benzil) ( مع الخطوة االولى ناتج مفاعلة الثانیةالخطوة و [H2L] یكاند الجدیدللتحضیر ال Co II, Ni II and Pd II اللیكاندثم مفاعلة [H2L] مع كل من للحصول على) 1:1( المیثانول وسطا للتفاعل وبنسبة المعباست و : العامةةمعقدات جدیدة ذوات الصیغ [M (H2L)]Cl2 :اذ M = Co II , Ni II and Pd II ، المرئیة–واألشعة فوق البنفسجیة ،األشعة تحت الحمراء ( :اآلتیةق الطیفیةائ بالطر المحضرةشخصت جمیع المركبات .مع قیاس التوصیلیة الموالریة الكهربائیة ، ومحتوى الكلور ودرجات االنصهار )ومطیافیة االمتصاص الذري للعناصر بینما ، رباعي السطوح المشوههو النیكلت ولا الكوبمقترح لمعقداتلان الشكل الفراغي اف التقنیات السابقةمن نتائج . مربع مستو شكلالبالدیومیتخذ