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 Co II,NiII,and PdII. E. I. Yousif Departme nt of Chemistry, College of Education, I bn Al-Haitham, Unive rsity of Baghdad Abstract A new Schiff base ligand [2,3,8,9–tetra -p henyl-1,4,5,7,10,12-hexa azo-5,12- dihydro -6,11- dione 1,3,7,10-dudec-tetra-ene] [H2L] and its comp lexes In general formula [M (H2L)]Cl2 (where : M = Co II , Ni II , and Pd II ) were p repared. This ligand was p repared in two st eps,in the first st ep a solution of benzil in methanol was reacted under reflux with semicarbazidhy drochlorid to give an (intermediate comp ound)[benzy l bis–(Semicarbazone)] which was reacted in the second st ep with benzil giving the mentioned ligand. The comp lexes Co II , Ni II , and Pd II were sy nthesized by direct reaction of the corresp onding metal chloride with the ligand [H2L].The ligand and comp lexes were characterized by sp ectroscop ic methods (IR, UV-Vis, and atomic absorp tion), chloride content and conductivity measurement.From the data of these measurements, we suggestred a tetrahedral geometry for Co II , Ni II comp lexs and a square p lanar for Pd II comp lex. Introduction Schiff b ases derived from condensation of semicarbazide with carbony l comp ounds were reported as comp lexing agents for various transition metal ions. M any chemist s have reported on the chemical st ructural and biological p rop erties of Schiff bases. Schiff bases are characterized by the –N=CH-(imine) group which is very imp ortant in elucidating the mechan ism of transmission rasemination reaction in some biolo gical sy st ems[1,2] . During the p ast two decades, considerable att ention has been p aid to the chemist ry of metal comp lexes of Schiff b ases containin g n itrogen and other donor atoms[3,4].T his may be att ributed to their st ability , 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- benzoy l py ridine N(4)-p heny lthiosemicarbazone with variety of cupper salts y ielded a series of cup p er (II) complexes. The present p ap er rep orts the sy nthesis and characterization of new ligand [2,3,8,9-tetra-p henyl-1,4,5,7,10,12-hexa azo- 5,12-dihydro-6,11-dione-1,3,7,10-dudec-tetra-ene] [H2L] and its comp lexes with Co II , Ni II and Pd II . Experimental Reagents were p urchased from Fluka and Rediel – Dehenge Chemical Co.I.R sp ectra were recorded as (KBr) disc by using a Shimadzu 8400 FTIR sp ectrop hotometer in the range (4000-450) cm -1 .Electronic sp ectra of the p repared comp ounds were measured in the region (200-1100) nm for 10 -3 M solution in (DM SO) at 25 0 C using a Shimadzu 160 sp ectrop hotometer with 1.000±0.001 cm -1 matched quartz cell . M etal contents of the comp lexes were determined by atomic absorp tion (A.A) technique by using a Shimadzu A.A 680G atomic absorp tion sp ectrop hotometer. The chloride contents for complexes were IBN AL- HAITHAM J . FO R PURE & APPL. SC I VO L.22 (4) 2009 determined by p otentiometric titration method on (686-titro p rocessor-665) ,Dosinat-metrom Swiss.Electrical conductivity measurements of the comp lexes were recorded at 25 0 C for 10 -3 M solutions in (DM SO) as a solvent by using a PW 9526 digital conductivity meter. S ynthesi s of the ligand [H2L] The ligand was prepa red in two ste ps. Step(1): Preparation of the [benzil bis -(Semicarbazone)] (intermediate compound). A solution of benzil (0.5g,2.37mmole) in methanol (5ml) was added to semicarbazidhy drochlorid (0.53g,2.37mmole) dissolving in methanol (5ml),and then(2-4) drop s of glacial acetic acid were added slowly to the reaction mixture .The mixture was refluxed for 5 hours, and allowed to dry at room temp erature for (24) hours. A white solid materal was obtained. Yield (89%),(0.69)g, m.p (215 0 C). S tep(2): Preparation of the [2,3,8,9-tetra-phe nyl-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)](intermediatecomp ound)(0.5g,1.543 mmole) in methanol (5 ml) was added to benzil (0.32g, 1.543mmole) dissolving in methanol (5ml), then (2-4) drop s of glacial acetic acid were added slowly to the reaction mixture .The reaction mixture was refluxed for (5) hours with st irring, filtered and the filtrate was allowed to dry at room temp erature for (48) hours. Then , it was washed with (5)ml diethy l ether and dried at room temperature to give the white solid materal. Yield (77%), (0.59) g ,m.p (235 0 C). S ynthesis of complexes All comp lexes were p repared by adding a drop wise of a solution of the ligand (H2L) (0.1g,0.2008mmole)in (5) ml methanol with st irring ,to 0.2008mmole of a solution of metal chloride salt M Cl2.XH2O dissolved in(5) ml methanol ,where:[M =Co II ,Ni II and Pd II ;X=6 for Co II ,Ni II and X=0 for Pd II ]. The reaction mixture was allowed to be refluxed for (2)hrs , let the coloury p recipitate formed which was filtered,washed with (5) ml diethy l ether and dried at room temp erature.Table(1)shows the st ated weight of metal chloride salt ,% y ield and some p hy sica p rop erties of the p repared comp lexes. Re sults and Discussion A-The ligand [H2L] The new ligand [H2L] was p repared in two st eps according to the general method of p reparation of Schiff base ligands [9] shown in scheme (1).The (I.R) sp ectrum for [H2L] (Fig. -2) , disp lay a band at 3209 cm -1 which is due to the υ(N-H) stretching vibration [10]. The band at 1687 cm -1 is att ributed to the υ(C=O) stretching vibration [11].The band at 1612 cm -1 is att ributed to υ (C=N) st retching frequency for the imine group vibration [12-13],while the two bands at 1025 cm -1 and 935 cm -1 were att ributed to the foramation of macrocy cle [14] .And finaly , the band at 1062 cm -1 is att ributed to (N-N) st retching vibration [15].The (U.V- Vis) sp ectrum(Fig.-3) exhibits a high intense absorp tion p eak at (300 nm ) (33333 cm -1 ) ( εm ax = 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 N H 2 N H C N OO N C H N H 2 N O O N H 3 C l N H 2 N H C O N H N C p h N OO N C ph N H N O p h p h + ( 5) h o ur s u n de r r e f u l xe gl ac ia l a c e t ic a ci d ( 2- 4) dr o p s B e nz i l S e m i ca r b az id h y d ro c h lor i d p h p h B e n z il b is - se m i c ar b az o n e + p h p h B e n z il ( 5) h ou r s u nd e r r e f u lx e gl ac ia l a c e t ic a ci d ( 2- 4) d r o p s p h p h 2 St e p (1 ) S t e p ( 2) -2 H 2 O S cheme (1) : Preparation of the ligand [H2L] B- Comple xes of Co II , Ni II and Pd II with [H2L] The sy nthesis of the comp lexes was carried out by the reaction of [H2L] with [M Cl2.XH2O] where M = [Co II ;X=6, Ni II ;X=6 and Pd II ;X=0] in methanol under reflux. These comp lexes are st able in solution and electrolyte (1:2) sy st ems in (DM SO) (Table- 3).The analytical and p hy sical data (Table-1) and sp ectral data (Table-3) are compatible with the suggested st ructures. The (I.R) sp ectra of complexes are p resented in (Table-2). The (I.R) sp ectra of the comp lexes show a band at 1679 ,1675 and 1670 cm -1 which are due to υ(C=O) st retching vibration for comp lexes (1) , (2) and (3) resp ectively. These bands were shifted to a lower frequency in comp arison 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 app eared at 1602,1605 and 1598 cm -1 for comp lexes (1),(2) and (3) resp ectively [12-14], showing a reducing in the bond order. This can be att ributed to delocalization of metal electronic density at (t2g) in the π sy st em of the ligand (HOM O → LUM O) [19]. Where HOM O = highest occup ied molecular orbital. LUM O = lowest unoccup ied molecular orbital. While the bands at 1074,1087 and 1085 cm -1 were assigned to υ (N-N) st retching vibration (15) in the comp lexes(1), (2) and (3) which were shifted to a higher frequency when it comp ared with free ligand. The app earance of the band at 698-507 cm -1 is due to υ(M -N) st retching .This suggests that the nitrogen of imine group was involved in coordination with the metal ion [20-23].Figs.(2a),(2b) and (2c) represent t he (I.R) sp ectra of[Co (H2L)]Cl2, [Ni (H2L)]Cl2 and [Pd (H2L)]Cl2.The (U.V-Vis) sp ectra for the comp lexes (1), (2) and (3) are shown in Figs.(3a) ,(3b) and (3c). The absorp tion sp ectral data for comp lexes are given in (Table -3). The sp ectra show two intense peaks in the U.V region at (300,357), (300,361) and (300,371) nm for comp lexes (1), (2) and (3) resp ectively. These peaks were assigned to ligand field and charge transfer transition resp ectively (24).Complex (1) exhibited the p eak at 609 nm which can be attributed to (d-d) electronic transition ty p e ( 4 A2→ 4 T1(p)). The observed IBN AL- HAITHAM J . FO R PURE & APPL. SC I VO L.22 (4) 2009 p eak in sp ectrum of comp lex (2) at 420 nm is assigned to (d-d) electronic transition ty p e ( 3 T1 → 3 T2 ) . The sp ectrum of comp lexe (3) exhibited the very intense p eak at 412 nm which can be att ributed to (d-d) electronic transition ty p e ( 1 A1→ 1 B1). These U.V-Vis data suggest a tetrahedral st ructure for Co II ,Ni II comp lexes and a square planar for Pd II comp lexe [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 .M ole -1 ) (Table-3) which indicated that t he comp lexes are electrolytic in nature with 1:2 ratio for all comp lexes [26]. The atomic absorp tion analysis and the chloride content results of the comp lexes are in a good agreement with the suggested formula [M (H2L)]Cl2. C H N N ph N ph N C N NH ph ph C H N N ph N ph N C N NH ph ph M+MCl2 .XH 2O m eth an ol ref luxe O O O O Cl 2 M=Co II , Ni II and Pd II S cheme (2) : Preparation of the metal complexes Re ferences 1. Lau ,K.Y.; M ayr, A.and Cheung, K .K (1999), “Sy nthesis of Transition M etal isocy anide comp lexes containin g hy drogen bonding sits inp erp heral 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.licHeterocy ly.J ”,hy droxy coumrin -4diazonium couplin g p roducts of 1403. 3. Djebbar,S. S. ;Benali, B.O. and Deloume. J.P.,(1997),Synthesis,characterization and electrochemical b ehavior of copp er(11)complexes with linear and trip odal 2182 - 2175:16, p olyhedron. ses tetradentate ligand der ived from Schiff ba 4. He. L .; Gou, S .H. and Shi, Q.F.(1999),T he formation of a Schiff base intermediate :a - 207:29.Chy st allogr . Chem.j.comp lexe of an asy mmetric trip odal ligand )11(nickel 210. 5. Liu.C. M .; Xiong, R.G. ;You, X.Z . ;Liu, Y.J. and Cheung, K.K.,(1996), Cry st al structure and some p rop erties of a novel p otent Cu2Zn2SOD model Schiff b ase cop p er (11) ).2006(61:15, p olyhedron. comp lexe 6. Hamada ,Y.J.(1997) T he develop ment of chelate metal comp lexes 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),Sy nthesis,characterization and electrochemical beh avior and cataly tic activity of manganese (11) comp lexes with linear -443 :23. Chem.M etal.Transit.and trip odal tetradentate ligands derived fro m Schiff bases 447. 8. M .Josep h, M . ;Kuriakose, M .R.P.; Kurup , E. and Suresh, S.G. Bhat.(2006). p olyhedron, 25:4565-4571. 9. Fedric M enger, M .; David, J.; Gold Smith and Leon M anden ,(1975),“ Organic chemistry ” Aconicise ap p roach ,2 nd .,W.A.Benijamin, Inc.,P.318. 10. M arlin,D. S. and M ascharak, P. K. Chem. Soc. Rev., 29 :69 (2000) 11. Parikh ,V.M . “Absorp tion sp ectroscopy of organic M olecules” Translated by Abdul Hussain Khuthier,jasimM .A.AL-Rawi,and M ahammed A.AL-Iraqi (1981). 12. Xishi Tai,Xianhong y in, Qian g chen,and M inyuta,(2003), “Synthesis of some Transition M etal comp lexes of a Novel Schiff B ase ligand Derived from 2,2-Bis (P-M ethoxy .440-439:8 , ”and Salicylicaldehyde M olecules amine p heny l 13. EL-Bindary , A.A.; AL-Shihri.A. S.; EL-Sonbouti, A.Z, (2003),Designed M onomers and p oly mers, 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 Sp ectroscopy ” 2 nd .Ed., 144. 17.Pavel kop el, M artin Biler, Zdenek.Travnicek,and M ilan Nadvorink ,(1998), “Iron( 111)Salen and Salop h Schiff bases brid ged by dicaboxy lic acids” chemical ,37. 18. Nakamoto, K. (1996) “ Infrared Sp ectra of Inorganic and Coordin ation Compounds ” 4 th .Ed.,J.Wiely and Sons , New York 19. Pinchas, S. and B en ,D. (1957)Ishai,j.Amer chem..Soc.79:4099,12. 20. Raju, K.C and Radhakr ishnan, P.K, (2003). “ Complexes of cupp er with 2,3Dimethy l-4- fomyl(benzhy drazide) -1-pheny l-3-py razolin-5-one”, Sy nthesis and reactivity in inorganic andmetal-organic chemistry ,33(8):1307-1318 21. EI.Tbleand A.S.; Kasher, T.I. ,(1998) p olish j.chem. 72:519. 22. EL-Sonb ati.A.Z . and EL-Bindary.A.A, (2000) “Stereo chemist ry of New Nitrogen cantaining Aldehydes .V.Novel Sy nthesis and sp ectroscop ic st udies of some Quinoline Schiff B ases com p lexes”,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 Sp ectroscopy ” 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=Co II , Ni II and Pd II . . Fig (1): The suggested structure for the complexes Table(1): S ome physical propertie s of the complexes and the weight of me tal chloride sal t. 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 ). Ot hor bands υ (M - N) υ (N- N) υ (C=N) υ( C=O) υ (N- H) Compound υ ( C=C) 1444 υ (c-H) alp h 2925 υ (C-H) arom 3047 - 1062 1612 1687 3209 [H2 L] υ (C=C) 1446 υ (c-H) alp h 2898 3060υ (C-H) arom 613 698 1074 1602 1679 3217 [Co (H2L] Cl2 υ (C=C) 1431 υ (c-H) alp h 2985 υ (C-H) arom 3053 603 636 1087 1605 1675 3220 [Ni (H2L)] Cl2 υ (C=C) 1442 υ (c-H) alp h 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) : Electroni c spectral data , and conductance me asurement for the ligand[H2L] and it’s complexes Compound λ nm Wave number Cm -1 εm ax M olar -1 .Cm -1 Assignment Λm(Ω. cm 2 .M ole -1 ) Prop ose st ructure [H2 L] 300 33333 2128 n →π* - - 300 33333 2111 Ligand field 357 28011 747 char ge transfer [Co (H2L)] Cl2 609 16420 121 4 A2→ 4 T1(p) 77.55 tetrahedral 300 33333 2362 Ligand field 361 27700 870 char ge transfer [Ni (H2L)] Cl2 420 23809 1846 3 T1→ 3 T2 79.11 tetrahedral 300 33333 2123 Ligand field 371 26954 915 char ge transfe [Pd (H2L)] Cl2 412 24271 611 1 A1→ 1 B1 72.03 Square p lanar IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L.22 (4) 2009 Fig. (2) .The I.R. S pectrum of the ligand [H2L] Fig. (2a) .The I.R. S pectrum of the [Co (H2L)] Cl 2 Fig. (2b) .The I.R. S pectrum of the [Ni (H2L)] Cl 2 Fig. (2c) .The I.R. S pectrum of the [Pd (H2 L)] Cl 2 IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L.22 (4) 2009 Fig. (3) .The U.V. S pectrum of the ligand [H2L] Fig. (3a) .The U.V. S pectrum of the [Co (H2L)] Cl 2 Fig. (3b) .The U.V. S pectrum of the [Ni (H2L)] Cl 2 Fig. (3c) .The U.V. S pectrum of the [Pd (H2 L)] Cl 2 (22مجلة ابن الھیثم للعلوم الصرفة والتطبیقیة المجلد 4 (2009 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-p henyl-1,4,5,7,10,12-hexaazo-5,12-dihydro-6,11-dione-1,3,7,10-dudec-tetra- ene] :طوتینخب semicarbazidhy) ( معbenzil) ( الخطوة االولى مفاعلة drochlorid [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