Research Journal of Chemical Sciences ______________________________________________ ISSN 2231-606X Vol. 4(10), 72-84, October (2014) Res. J. Chem. Sci. International Science Congress Association 72 Synthesis and Characterization of Salicylaldazine (HL) and its mixed Ligand complexes [ML(HO)], [M(LH)(caf)] ; M= Zn2+, Cd2+, Ni2+, Cu2+, Co2+, Mn2+, Fe2+ ; n=1,2 ; Caf= caffeine El Amane Mohamed*, Kennouche Youness and Hamidi M. El M.1 Equipe métallation, complexes moléculaires et application, Faculté des sciences, BP 11201 Zitoune, Meknès, MOROCCO L.P.C.M., Faculty of Science and Technology, University Moulay Ismaïl, B. P. 509 Boutalamine, Errachidia, MOROCCO Availableonline at: www.isca.in, www.isca.me Received 24th September 2014, revised 2nd October 2014, accepted 15th October 2014 Abstract. The ligand salicylaldazine (HL) was prepared by condensation of salicylaldehyde and hydrazine in (2/1) molar ratio. The synthesized ligand was investigated using different physical techniques such as infrared, Raman spectroscopy, H, 13C NMR and UV-Visible. Transition metal complexes [ML(HO)];M= Zn2+, Cd2+, Ni2+, Cu2+, Co2+, Mn2+, Fe2+ and the mixed ligand complexes [M(LH)(caf)]; M= Zn2+, Cd2+ for n=1 and M= Ni2+, Cu2+, Co2+, Mn2+,Fe2+ for n=2 derived from the ligand have been widely studied. The infrared, Raman and UV-Visible data of the metal complexes show that the ligand is coordinated to the metal ions in a tridentate manner, with NOO donor sites of the azine. It is also found that the geometrical structures of these complexes are tetrahedral. Based on the obtained infrared, Raman, NMR spectroscopy, UV-Visible and literature indications, the ligand is coordinated to the metal in bidentate manner through NO donor sites of the azine and with N9 imidazol of the caffeine. Thus, the mixed ligand complexes [M(LH)(caf)] exhibit a distorted pentahedral geometry for n=1; M=Zn2+, Cd2+ and a distorted octahedral geometry for n=2; M= Ni2+, Cu2+, Co2+, Mn2+ , Fe2+. Keywords: Salicylaldazine, caffeine, complexes, FT-IR, Raman, H, 13C NMR, UV-Visible, molar conductance. Introduction Azines, RC=N—N=CR, have achieved great significance in organic synthesis1-3. Many studies have shown that azines are good synthones for obtaining heterocyclic compounds such as pyrazols, purines and pyrimidines. These compounds can be utilized for some useful synthetic transformations and they constitute an important class of compounds with unexpected biological activities. Azines are obtained of condensation between the hydrazine and two carbonyl compounds. Azines, and aromatic azines, are receiving increasing attention for their biological, chemical and physical properties7–10. Salicylaldazine (scheme-1) and other ligands essentially containing a (C=N) group have been popularly called Schiff bases, which are versatile multidentate ligands capable of bonding from several alternate sites resulting in the formation of metal complexes having suitable properties for theoretical studies and practical applications11. They constitute an interesting class of chelating agents capable of coordinating with one or more metal ions giving mononuclear as well as polynuclear metal complexes. Scheme-1Structure of the caffeine Caffeine (1, 3,7-trimethylxanthine) (scheme-1) is one of purine alkaloids and it belongs to xanthine chemical groups and it plays an important role in pharmacological properties15. Caffeine probably is the most popular drug in the world16, which includes antagonistic effect on adenosine receptors, inhibition of phosphodiesterase and stimulation of muscle contraction17, 18. In this paper, we have been undertaken in order to get information on the structure of the salicylaldazine (HL), metal and caffeine complexes ([ML(HO)] and [M(LH)(caf)]; n=1,2) using FT-IR, Raman , H, 13C NMR, UV-Visible and molar conductance. Material and MethodsAll chemicals were obtained from commercial sources and were used without purifications: (NiCl, 6HO BDH; ZnCl, 2HO BDH; CdCl,1/2HO Panreac; CuCl, 6HO BDH; MnCl, 2HO BDH ; CoCl, 6HO BDH ; FeCl, 4HO BDH), hydrazine Sigma Aldrich, salicylaldehyde SAFC, Ethanol and DMSO Sigma Aldrich. Infrared spectra were recorded as KBr pellets on a Shimadzu 460 spectrophotometer in the range of 4000–400 cm-1 at 298 K. Raman spectra were recorded with Vertex 70, while the electronic spectra (UV–Vis) were obtained on a Shimadzu UV-1800 Spectrophotometer. The H, 13C NMR spectra of the Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 4(10), 72-84, October (2014) Res. J. Chem. Sci. International Science Congress Association 73 ligand was recorded with a Bruker AVANCE 300 at 25°C. All chemical shifts H and 13C are given in ppm using tetramethylsilane (TMS) as internal reference and DMSO as solvent. Conductivity measurements were performed at 25°C in acetonitrile using Hach HQ430d flexi. Synthesis of the salicylaldazine (HL): The salicylaldazine ligand (HL) was prepared by adding a ethanol (15 ml) solution of salicylaldehyde (0.02 mol, 2.44g) to hydrazine (0.01mol, 0,5 g). The mixture was refluxed for two hours. The yellow powder-like product was collected by filtration and washed several times with ethanol. (Yield (%)= 88) Synthesis of the metal complexes [ML(HO)]; M= Zn2+, Cd2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+ Complexes of Zn2+, Cd2+, Ni2+, Cu2+, Mn2+, Fe2+ and Co2+ were synthesized using a general procedure : The salicylaldazine ligand (HL) was prepared in the presence of a metal ion in the reaction mixture. (0.001 mol, 0.24g) of salicylaldazine ligand (HL) with (0,002 mol, 1.12g) of hydroxyl potassium (KOH) were dissolved in the 10 ml of ethanol and 0.001 mol of a metal (chloride) salt (MnCl (0.2 g), FeCl (0.13 g), CoCl2 (0.24 g), NiCl (0.24 g), CuCl2 (0.17 g), ZnCl (0.14 g) and CdCl2 (0.23 g)) was added to the resulting solution, which was shaken and/or heated until all of it dissolved. This mixture was refluxed for about two hours. The resulting colored precipitate was then filtered off and washed several times with ethanol. Synthesis of the mixed ligand complexes [M(LH)(caf)]; M= Zn2+, Cd2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+ ; n=1,2; caf= caffeine: Complexes of Ni2+, Cu2+, Mn2+, Fe2+ and Co2+ with caffeine were prepared by adding (0,001 mol) of a metal (chloride) salt (MnCl (0.2 g), FeCl (0.13 g), CoCl (0.24 g), NiCl (0.24 g), CuCl (0.17 g)) to (0,002 mol, 0.48 g) of the salicylaldazine ligand (HL) with (0,002 mol, 1.12g) of hydroxyl potassium (KOH) in ethanol and (0,002 mol, 0.39 g) of the caffeine in ethanol dropwise with stirring for 2h. In the same way, the caffeine complexes of Zn2+ and Cd2+ were synthesized by adding (0,001 mol) of a metal (chloride) salt ZnCl (0.14 g) and CdCl (0.23 g)) to (0,002 mol, 0.48 g) of the salicylaldazine ligand (HL) with (0,002 mol, 1.12g) of hydroxyl potassium (KOH) in ethanol and (0,001 mol, 0.20 g) of the caffeine in ethanol drop wise with stirring for 2h. All caffeine complexes were formed and settled down on standing. They were filtered and washed with ethanol. Results and discussion Characterization of the Salicyldazine ligand (HL): The proposed structure ofsalicylaldazine (HL) is shown in scheme-2. This structure was confirmed by X-ray diffraction in our previous study19. Then, the salicylaldazine (HL) crystallizes in the monoclinic space group P2/n and it has unit cell dimensions: a= 8,3988 (6) b= 6,2980(4) c= 11,6697(8) = 90° = 107,054° Scheme-2 Molecular structure of salicylaldazine (HL) This crystallographic data are in agreement with the conformation (E, E). In other study published recently11, we carried out a theoretical study of N, N'-di (ortho-substituted benzyl) hydrazine with R = H, Me, OH and OMe with Theory Density Functional (DFT) using the hybrid method B3LYP with the basis 6-31G (d) and the semi-empirical method ZINDO. The Gaussian 03 program has been used to predict structural geometries of of N, N'-di (ortho-substituted benzyl) hydrazine in gas phase. H NMR spectra: H NMR spectrum of the Salicylaldazine (HL) (figure-1) was recorded in DMSO. The spectrum exhibits a multiplet at (6.94-7.70) ppm for the hydrogens of the aromatic rings. The azomethine hydrogen (-CH=N-) leads to a singlet of integration intensity equivalent to one hydrogen at 8.99 ppm. Furthermore, the spectrum exhibit a signal due to the hydrogen bonded hydroxyl group at 11.07 ppm. We note that the singlet observed at 2.48 ppm corresponds to protons of methyl of DMSO. Figure-1H NMR spectrum of Salicylaldazine (HL) in DMSO 13C NMR spectra: More detailed information about the structure of ligand was provided by 13C NMR spectral data. A summary of the 13C NMR chemical shifts for the ligand is given in table-1. 13C NMR spectrum (figure-2) exhibits the azomethine C=N carbon (C1) at 163.23 ppm. The aromatic carbon atoms (C2, C3, C4, C5, C6 and C7) are observed at 118.69 ppm, 159.14 ppm, 117.01 ppm, 133.64 ppm, 120.04 ppm and 131.36 ppm, respectively. We note that the (Cx) at 40.25 ppm is attributed to methyl carbon of DMSO. Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 4(10), 72-84, October (2014) Res. J. Chem. Sci. International Science Congress Association 74 Figure-2 13C NMR spectrum of salicylaldazine (HL) in DMSO Infrared and Raman spectroscopy: Salicylaldazine ligand (HL) was previously found to have a C2h symmetry from an X-ray diffraction19,20 and IR, Raman spectroscopy in the solid state and in solution13,14. Its vibrations can thus be distributed as vib=35A+34B+17A+16B. Selected infrared and Raman absorption of the salicyladazine (HL) are shown in table-2. The infrared and Raman spectra of salicylaldazine (HL) are given in figure-3 and figure-4 respectively. Figure-3Infrared spectrum of salicylaldazine (HL) in KBr In the study of hydrogen bonding for a salicyladazine (HL), it was possible to confirm that the salicyladazine (HL) form several kinds of hydrogen bonded species, such as –OH…O intermolecular hydrogen bonding, -OH…O intermolecular hydrogen bonding and –H…N intermolecular bonding21. Then, in the infrared spectrum of the salicylaldazine (HL), the bond centered at 3445 cm-1 shows the existence of –OH…O intermolecular hydrogen bonding, and the broad band between 2941 cm-1 and 2606 cm-1 might be designated for –OH…O intermolecular hydrogen bonding and –OH…N intermolecular hydrogen bonding. It is well estabilished that the Schiff bases having o-hydroxy group either on aldehyde or aniline residue can form intermolecular hydrogen bonding with azomethine nitrogen (scheme-3)22. This has direct impact on the (OH) vibrations and the band due to (OH) shifts to the lower frequency with broadening of the band and decrease in the intensity. The extent of shift depends on the strength of hydrogen bonding23. Scheme-3Tautomerism in the salicylaldazine (HL) The IR spectrum of the salicylaldazine (HL) shows also a weak band at 3019 cm-1, assigned to (CH, Ar-H). The s(C=N) are only observed in the Raman spectrum13, whereas a(C=N) are observed in the Infrared spectrum13. The very strong band at 1622 cm-1 in infrared spectrum of salicylaldazine and at 1594 cm-1 in Raman spectrum of salicylaldazine due to asymmetric and symmetric azomethine (C=N) linkage respectively. The bands at 1567 cm-1 and 1479 cm-1 are attributed to (C=C). The band appearing in the (1443-1300) cm-1 can be connected to CH+ (C-N). Two interesting bands observed at 1328 cm-1and 1280 cm-1 represent the vibrations modes (C-O)ph and (OH) respectively. In the Raman spectrum of the salicylaldazine (HL) (figure-4), the vibration (N–N) was located at 1063 cm-1 which is absent in the IR spectrum. This result is comparable to those found for others arylazines24. Figure-4Spectre Raman de salicylaldazine (HL) Bands in the (1162-1038) cm-1 range due to (CH) in plane deformation. The medium and/or weak band observed in the (990-739) cm-1 range can be attributed to (CH) out-of-plane deformation. Bands in the (687-624) cm-1 is assigned to (CH) in plane ring deformation and the bands in the (569-416) cm-1range is attributed to (CH) out plane ring deformation. Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 4(10), 72-84, October (2014) Res. J. Chem. Sci. International Science Congress Association 75 UV/Visible spectra: The UV and visible data of salicylaldazine (HL) is summarized in table-3. The spectrum of salicylaldazine (HL) in acetonitrile (figure-5) exhibits two intense bands at 221 nm and 292 nm which are attributed to *(phenyl ring). Other important band at 354 nm is assigned to n* of azomethine group (C=N). Figure-5 Electronic spectrum of salicylaldazine (HL) Characterization of the mixed ligand complexes [ML(HO)] and [M(LH)(caf)] ; M= Zn2+, Cd2+, Ni2+, Cu2+, Co2+, Mn2+, Fe2+ ; n=1, 2; caf= caffeine: After establishing the chemical composition, the complexes were studied by physical and chemical techniques for elucidating their coordination number, bonding sites and stereochemistry. The chemical and physical methods employed for structural investigation of the complexes in the present work are: FT-IR, Raman, H NMR, electronic spectra and molar conductance. Conductance measurement: All complexes prepared in this work showed conductivity values ranged between (6.55-5.08) Ohm-1.mol-1.cm, in DMSO at room temperature, these values indicating that no conductivity species exist. The conductivity measurements data are listed in table-4. Infrared and Raman spectroscopy of the metal complexes [ML(HO)]; M= Zn2+, Cd2+, Ni2+, Cu2+, Co2+, Mn2+, Fe2+: The infrared spectra of the metal complexes [ML(HO)]; M= Zn2+, Cd2+, Ni2+, Cu2+, Co2+, Mn2+ and Fe2+ are compared with that of the salicylaldazine (HL) to determine the changes that might have taken place during the complexation. The infrared and Raman spectral data of the metal complexes [ML(HO)]; M= Zn2+, Cd2+, Ni2+, Cu2+, Co2+, Mn2+ and Fe2+ are given in table-2. The infrared and Raman spectra of [ZnL(HO)] are given in figure-6 and figure-7, respectively. Figure-6 Infrared spectrum of the Zn2+ complex [ZnL(HO)] in KBr Figure-7 Raman spectrum of the Zn2+ complex [ZnL(HO)] The infrared band assignments of all metal complexes exhibit broad bands in the (3341-3409) cm-1 range indicating the presence of coordinated water molecule25. For the salicylaldazine (HL), the broad bands in the (2900–2600) cm-1range are assigned to the OH group vibration (ortho position) associated intramolecularly with the nitrogen atom of the CH=N group25. These bands disappear in the metal complexes [ML(HO)]; M= Zn2+, Cd2+, Ni2+, Cu2+, Co2+, Mn2+ and Fe2+ as a result of proton substitution by cation coordination to oxygen. On coordination with Zn2+, Cd2+, Ni2+, Cu2+, Co2+, Mn2+ and Fe2+, the a(C=N) band of salicylaldazine (HL) is observed to shift towards the lower frequency region ((1610-1593) cm-1, which suggests that the metal-ligand electron interaction in the newly formed chelate rings changes the vibrational frequency of the C=N group. In the Raman spectra, the s(C=N) was located at 1594 cm-1 for Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 4(10), 72-84, October (2014) Res. J. Chem. Sci. International Science Congress Association 76 the salicylaldazine (HL). This band was shifted to the (1592-1547) cm-1 range for the metal complexes [ML(HO)]; M= Zn2+, Cd2+, Ni2+, Cu2+, Co2+, Mn2+, Fe2+. In the infrared spectra, the s(C=N) wasn’t appeared. In the region (1587-1458) cm-1, two or three bands are observed in the case of Zn2+, Cd2+, Ni2+, Cu2+, Co2+, Mn2+ and Fe2+complexes, which may be assigned to the C=C stretching vibration of the phenyl groups. The observed phenyl ring bands shift towards the low frequency region in all the metal complexes. The bending vibration CH and stretching vibration (C-N) are located in the (1438-1300) cm-1 range. These vibrations are shift to lower frequencies confirming the coordination of the salicylaldazine (HL) through the azomethine nitrogen atom. The next important absorption band in the salicylaldazine (HL) is found at 1328 cm-1 and it is attributed to the (C-O) stretching vibration26. In the metal complexes of Zn2+, Cd2+, Cu2+, Ni2+, Fe2+, Mn2+ and Co2+, this band disappears from this position and appears at a higher frequency region (1375-1330) cm-1. This shift to higher frequency is expected due to the main tenure of ring currents arising from electron delocalization in the chelatering. The band at 1280 cm-1 assigned to OH of salicylaldazine (HL) is disappeared for the metal complexes. The stretching vibration (N-N) in the Raman spectra of the metal complexes [ML(HO)]; M= Zn2+, Cd2+, Ni2+, Cu2+, Co2+, Mn2+, Fe2+ was shifted to (1060-1045) cm-1, respectively by (3-18) cm-1. Moreover, this negative shift in (N-N) vibration on complexation can be added as a further support to the coordination of the azomethine nitrogen atom to the metal ion. Such coordination is further substantiated by the appearance of new bands in the complexes characteristic of (M–N) and (M–O) in the (596-576) cm-1 and (456-432) cm-1 regions, respectively27–28. Infrared and Raman spectroscopy of the mixed ligand complexes [M(LH)(caf)];M= Zn2+, Cd2+, Ni2+, Cu2+, Co2+, Mn2+, Fe2+ ; n=1,2; caf= caffeine: Comparison of infrared and Raman spectra of salicyladazine ligand (HL) and free caffeine with that of their complexes [M(LH)(caf)]; M= Zn2+, Cd2+, Ni2+, Cu2+, Co2+, Mn2+ and Fe2+; n=1,2have been adopted to determine the coordinating atoms of the salicyladazine ligand (HL) and the free caffeine to metal ions. The infrared and Raman spectra of the caffeine complexes [Cd(LH)caf] are shown in figure-8 and figure-9 respectively. The assignments of the seven studied caffeine complexes [M(LH)(caf)] ; M= Zn2+, Cd2+, Ni2+, Cu2+, Co2+, Mn2+ and Fe2+; n=1,2are reported in table-5. From the literature29,30, the infrared and Raman spectral data of the free caffeine are given in the table 5. Then, the infrared spectra of the caffeine complexes [M(LH)(caf)] ; M= Zn2+, Cd2+, Ni2+, Cu2+, Co2+, Mn2+, Fe2+ n=1,2 exhibit the vibration (OH) stretching in the (3452-3450) cm-1 range. Figure-8 Infrared spectrum of the Cd2+ caffeine complex [Cd(LH)caf] in KBr Figure-9 Raman spectrum of the Cd2+ caffeine complex [Cd(LH)caf] The medium/weak bands in (3113-3002) cm-1 range are attributed to CHar. The carbonyl group in the caffeine complexes exhibit a strong absorption band about 1700 cm-1 due to (CO) symmetric. Another strong band in the (1656-1646) cm-1 range belong to (CO) asymmetric and (C=N) is shifted to lower frequencies by (6-16) cm-1, compared with the free caffeine, indicating coordination of the caffeine through the azomethine nitrogen atom (N9)31. The next strong band at 1622 cm-1 attributed to (C=N) symmetric of the salicyladazine (HL) shifted towards a lower frequency by (12-24) cm-1. The (C=N) asymmetric of the salicyladazine (HL) is appeared only in the Raman spectra and shifted to (1589-1551) cm-1 region by (5-43) cm-1 on coordination due to the decrease of the bond order as a result of metal nitrogen bond formation. In addition, the band at 1551 cm-1 is assigned to (HCN+ ring imid +ring pyrimi) which is shifted to lower frequencies by (13-31) cm-1 compared with the free caffeine. Then, we may Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 4(10), 72-84, October (2014) Res. J. Chem. Sci. International Science Congress Association 77 confirm that imidazol fragment of the caffeine is coordinated with metal ions through the nitrogen atom N9 32. The band of salicylaldazine (HL) at 1328 cm-1 which involves the (C-Oph) stretching as the major coordinate shifts to (1356-1335) cm-1region for all caffeine complexes26. This shift to higher frequency is expected due to the main tenure of ring currents arising from electron delocalization in the chelate ring. Indeed, other vibration (OH) is appeared at 1275 cm-1 in all caffeine complexes which confirm that one of two hydroxyls group isn’t coordinated with metal ions. The Raman spectra of the caffeine complexes show the stretching vibration (N-N) in (1061-1054) cm-1 which is shifted to lower frequencies by (2-9) cm-1 and isn’t appeared in the Infrared spectra. New bands are attributed to (M-N) and (M-O) vibrations, respectively. The appearance of these new bands vibrations in (590-575) and in (450-425) cm-1 ranges respectively supports the involvement of nitrogen and oxygen atoms in complexation with metal ions under investigation33, 34. H NMR spectra of the mixed ligand complexes [M(LH)caf]; M=Zn2+ and Cd2+: The H NMR spectra of the caffeine complexes [M(LH)caf] M= Zn2+ and Cd2+ were recorded in dimethylsulfoxide (DMSO). The H NMR spectra of these complexes show the following signals: Phenyl as multiplet at (6.79-7.64) ppm. The signal attributed to proton of CH=N– is shifted to 8.93 ppm and 8,92 ppm for Zn2+ and Cd2+ caffeine complexes, respectively, indicating the coordination of azomethine to Zn2+ and Cd2+. In other hand, the H NMR spectrum of the free caffeine has shown proton signals at 3.30, 3.54, 3.90 and 7,76 ppm corresponding to the three methyl groups N1-CH, N3-CH, N7-CH and C8-H respectively35. In the case of Zn2+ and Cd2+ caffeine complexes, the signals of N1-CH, N3-CH and N7-CH are shifted to 3.20, 3.40 and 3,86 ppm. The signal due to the C8-H was shifted to 7.92 and 7.94 on the Zn2+ and Cd2+ complexation, respectively. The downfield shift was attributed to the involvement of N9 in complexation. UV/Visible spectra: Information concerning the geometry of the complexes was obtained from the electronic spectra. Upon the electronic spectrum of the salicylaldazine (HL), the two essential absorption bands were observed at 354 nm and at (221 and 292) nm, assigned to the transitions n *, *, respectively (figure-5). These transitions were existed also in the spectra of the complexes, but they shifted to different lower intensities, confirming the coordination of the salicylaldazine (HL) to the metal ions. In UV-Visible spectra, the weak band should be at 400-300 nm is due to charge-transfer (CT) band in the complexes [ML(HO)] and [M(LH)(caf)]; M= Zn2+, Cd2+,Ni2+, Cu2+, Co2+, Mn2+ and Fe2+; n=1,2 which is absence in the salicylaldazine (HL). However, the weak broad band at 1000-400 nm is due to different d-d transitions of the metal ions as mentioned. The electronic spectral data for all complexes are given in table-3. UV/Visible spectra of the metal complexes [ML(HO)]: The electronic spectrum of Fe2+ complex [FeL(HO)]is given in figure-10. The spectrum of the Co2+ complex [CoL(HO)]shows an absorption band at 448 nm, attributed to (F) (F) transition. Another bands appeared at 892 and 928 nm were assigned to (F) (F). These values are accepted for Co2+ tetrahedral complexes34. The Mn2+ complex [MnL(HO)] show two absorption bands at 386 cm-1 and 494 cm-1 assigned to 1g1g and 1g2g transition respectively, suggest the tetrahedral geometry of Mn2+36. The spectrum of the Ni2+complex [NiL(HO)] shows two absorption bands at 496 nm and 931 nm, attributed to the electronic transitions (F)(F), (F)(P) and (F)(F) respectively. These transitions are characteristic for tetrahedral complexes of Ni2+34. The green complex of Cu2+ [CuL(HO)]exhibited an absorption band in the visible region at 402 nm which belong to electronic transition E 37. The electronic spectrum of the Fe2+ complex [FeL(HO)]consisted of a pair of low intensity bands at 550 and 905 cm-1, arising from 2 transitions, suggest the tetrahedral environment of Fe2+37. The electronic configurations of Zn2+ and Cd2+ complexes were (d10) which confirms the absence of any (d-d) transitions. The absorption bands in their spectra were suffered blue shift with Hypo or Hyper chromic effect 34, 38. Figure-10 Electronic spectrum of the Fe2+ complex [FeL(HO)] in acetonitrile UV/Visible spectra of the mixed ligand complexes [M(LH)(caf)]; M= Zn2+, Cd2+,Ni2+, Cu2+, Co2+, Mn2+, Fe2+; n=1,2; caf= caffeine: The electronic spectrum of Cu2+ caffeine complex [Cu(LH)(caf)] is given in figure-11. The electronic spectrum of the Mn2+ caffeine complex shows two bands at 356 nm and 450 nm assigned to 1g (4G) and 1g (4Eg), respectively, for a Mn2+ ion in an distorted octahedral field39. The electronic spectrum of the Fe2+ caffeine complex shows absorption band at 535 nm assignable to the 2g transition consistent with an octahedral geometry for Fe2+ caffeine complex40.The electronic spectrum of octahedral Cu2+ caffeine complex has three types of transitions observed at 634 nm due to (D) 2g(D). Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 4(10), 72-84, October (2014) Res. J. Chem. Sci. International Science Congress Association 78 Figure-11 Electronic spectrum of the Cu2+ caffeine complex [Cu(LH)(caf)] in acetonitrile The electronic spectrum of the Co2+ caffeine complex shows two d-d bands at 286, 436 and 781 nm assignable to 1g(F) 2g(F) , 1g(F) 2g(F) and 1g(F) 1g(P) transitions respectively, in an octahedral geometry41. The electronic spectrum of the Ni2+ caffeine complex shows three d-d bands at 396 and 985 assignable to 2g(F) 1g(F) and 2g(F) 2g(F) respectively, in octahedral geometry42. The Zn2+ and Cd2+ caffeine complexes are found diamagnetic as expected from their electronic configurations and may have pentahedral geometry43. Conclusion From the previous analysis we can conclude that the metal complexes and the mixed ligand complexes were found to have the general formulae [ML(HO)] and [M(LH)(caf)] n=1,2, respectively. All complexes were synthesized and characterized by molar conductance, infrared, Raman, UV-Visible and 1H NMR spectra. Based on the obtained experimental data and literature indications, structural formulae to these complexes were assigned. Table-113C NMR spectral data of the Salicylaldazine (HL) Carbone 1 2 3 4 5 6 7 (ppm) 163.23 118.69 159.14 117.01 133.64 120.04 131.36 Table-2Infrared and Raman data of the salicylaldazine (HL) and its metal complexes [ML(HO)]; (M= Zn2+, Cd2+, Ni2+, Cu2+, Co2+, Mn2+, Fe2+) Values in () are the Raman data of the metal complexesSalicyladazine (H 2 L) CdL(HO) ZnL(HO) FeL(HO) CuL(HO) NiL(HO) CoL(HO) MnL(HO) nnOH/HO 3445 m,br 3409 m,br 3341 m,br 3380 m,br 3391 m,br 3385 m,br 3345 m,br 3345 m,br nn CHar 3019 m (3000m) 3002w (3016) 3055w (3052w) 3053w (3040w) 3075w, 3010w (3005w) 3040w (3038w) 3012w (3050w) 3025w (3034w) OH….N 2941w,2709w, 2606w - - - - - - - nnaC=N, dd 2 O 1622vs (1624s) 1610vs (1605s) 1610vs (1581s) 1593vs (1609s) 1606vs (1605m) 1600vs (1606vs) 1600vs (1621m) 1606vs (1607s) nnsC=N (1594s) (1580s) (1550s) (1580s) (1588m) (1547vs) (1592s) (1586s) nnC=C (ring) 1567s, 1479s (1552vs, 1490w, 1455s) 1535s, 1462s (1542vs, 1473s,1443s) 1530s, 1458m (1537vs, 1471s, 1449s) 1569s, 1528s 1478w,1458m (1550vs, 1466s, 1449s) 1587s, 1525s, 1458m (1550m, 1480m, 1450m) 1528s, 1460vs (1547vs, 1470m, 1451m) 1571s, 1519s, 1458m (1550vs, 1454s) 1572s, 1520s, 1492w, 1457m (1534vs, 1472m, 1455m) ddCH + nnC-N 1443m, 1382m, 1300m (1430w,1384w) 1425s,1397w,1379w 1300s (1400w) 1431m,1380m 1300m (1400w) 1426m,1305m (1410m, 1348w, 1318m) 1438s,1316m (1410w, 1341w, 1316m) 1434s, 1300m (1400w) 1434s, 1372m 1310m (1320m) 1433s, 1372m, 1312m (1442m, 1411m, Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 4(10), 72-84, October (2014) Res. J. Chem. Sci. International Science Congress Association 79 1329m) nnC-Oph 1328s (1322m) 1330m (1332m) 1336m (1340w) 1373m (1377w) 1374m (1365w) 1375m (1344m) 1353m (1368m) 1350m (1369m) ddOH 1280vs - - - - - - - nnC-HPh 1238w, 1203s (1244m, 1210w) 1247m (1252w, 1206m) 1252w (1244w, 1204w) 1240w, 1200m (1240w) 1242w (1244m) 1250m (1237w) 1255w, 1201m (1243m, 1208m) 1251w, 1200m (1291w, 1255m, 1208w) ddCH (ring) In plane bend 1162m, 1152m, 1118m, 1038m (1155w, 1118m, 1031m) 1190s, 1152s, 1123m, 1038m (1154m, 1125w, 1088w, 1012s) 1192m, 1155m, 1126w, 1029w (1156w, 1118w, 1022m) 1147m, 1122m, 1029m (1146w, 1117w, 1017m) 1195s, 1148s, 1130m, 1017w (1150w, 1120w, 1015w) 1194m, 1151m, 1124m, 1031m (1196w, 1152w, 1028m) 1154m, 1130w, 1003m (1153w, 1029m) 1151m, 1126m (1155w, 1120m, 1090w) nnN-N (1063s) (1045w) (1056m) (1057m) (1055m) (1058m) (1060m) (1056m) CH (ring) Out-of-plane bend 990m, 981m, 949w, 901m, 859w, 839w, 790m, 760vs, 739m (999m, 795w) 981w, 956m, 932m, 905m, 834w 855m, 800s, 760s, 734s (963m, 943w, 918w, 815w, 766w) 997w, 966w, 907w, 847w, 800w, 774w, 746m, 732w (918w, 813w) 997w, 981w, 938w, 900w, 857w, 832w 800w, 779m, 749m (960w, 946w, 920w, 815w, 796m) 958m, 902m, 852m, 835w 800w, 750m, 737m (985w, 950w, 915w, 815w, 788w) 982w, 971w, 920w, 900m, 852m, 830w 781w, 748m (985w, 960w, 945w, 815w, 766w) 969w,940w 908m 867w,856w 832w 803w,760m711w (794w) 997m,963w, 932w,902w, 848w, 832w 796w,755m, 700w (995w,960w 910w,850w822w, 788w) CH In plane ring def 687m, 655w, 624w (655vw) 670m, 615w (634w) 670m, 623w, 604w (630w) 685w, 622m (644w) 660w, 644w, 620w (641w, 614w) 675m, 657w, 621w (655w, 610w) 665w, 638w, 617w 656w,629w 611w (650w, 605w) nnM-N - 596m (593w) 593w (587w) 585m (588w) 576m (586w) 583m (580w) 578w (580w) 577w (585w) CH Out-of-plane ring def 569m, 555w, 520w, 491w, 478w, 460w, 440m, 416w (550vw, 530w, 450vw, 420vw) 542w, 465m, 411w (554w) 550w, 524w, 487w, 470w, 406m (540w) 555w, 537w, 490w, 478w, 460w, 410w (550w) 538w, 411w (550w, 420w) 555w, 534w, 492w, 460w, 407m (555w,) 545w,479w467w,415w (529w) 535w,472w460w, 406w (558w,546w 455w,422w) ddCCN 510w 494m 500w 507w (503w) 498w (500w) 506m (506w) 513w 504w (505w) nnM-O - 434w (428w) 456m (445w) 432w (450w) 451w (449) 443m (445w) 455w (443w) 444w (440w) Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 4(10), 72-84, October (2014) Res. J. Chem. Sci. International Science Congress Association 80 Table-3 U.V-Visible data of the salicylaldazine (HL), the caffeine, the metal complexes and the mixed ligand complexes in acetonitrile Compound max (nm) Assignment caf 275 316 365 * * * L 221 292 354 * * * [FeL(HO)] 202, 238 357 550 905 CT L E [CoL(HO)] 204, 282 357 448 892, 928 CT L (F) (F) 2 (F) 2 (F) [MnL(HO)] 204, 234, 292 349 365 403 CT L 1g1g 1g 4T 2g [NiL(HO)] 204, 275 357 496 931 CT L (F) (F) (F) (P) 1 (F) 2 (F) [CuL(HO)] 204, 282 350 402 CT L 2 E [CdL(HO)] 214, 286 400 CT Red Shift with hypochromic effect [ZnL(HO)] 214, 282 389 CT Red Shift with hypochromic effect [Fe(LH)(caf)] 204, 276 356 535 CT L 2g 5E g [Co(LH)(caf)] 206, 262 286 436 781 CT 1g(F)2g(F) 1g(F) 2g(F) 1g (F) 1g (P) [Mn(LH)(caf)] 202, 289 356 450 CT 1g1g (4G) 1g 4T 1g (4Eg) [Cu(LH)(caf)] 204, 272 634 CT g (D) 2g (D) [Ni(LH)(caf)] 202, 286 396 985 CT 2g(F) 1g(F) A2g(F) T2g(F) [Cd(LH)(caf)] 205, 289 364 CT Red Shift with hypochromic effect [Zn(LH)(caf)] 202, 292 359 CT Red Shift with hypochromic effect Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 4(10), 72-84, October (2014) Res. J. Chem. Sci. International Science Congress Association 81 Table-4Physical characterization and Molar Conductance data of the complexes [ML(HO)] and [M(LH)(caf)]; M= Zn2+, Cd2+, Ni2+, Cu2+, Co2+, Mn2+, Fe2+ ; n=1,2; caf= caffeine Complexes Colour M.P. (°C) Yield (%) (Ohm - 1 cm 2 mol - 1 ) [ZnL(H 2 O)] Yellow �260 82 5.34 [CdL(H 2 O)] Yellow �260 76 5.76 [NiL(H 2 O)] Light Green 250 72 5.87 [CuL(H 2 O)] Dark Green �260 68 5.90 [CoL(H 2 O)] Light Brown �260 78 5.92 [MnL(H 2 O)] Dark Orange �260 75 5.46 [FeL(H 2 O)] Black �260 70 6.55 [Zn(LH) 2 caf] Yellow �260 77 5.08 [Cd(LH) 2 caf] Yellow �260 83 5.14 [Ni(LH) 2 (caf) 2 ] Light Green �260 78 5.28 [Cu(LH) 2 (caf) 2 ] Dark Green �260 76 5.44 [Co(LH) 2 (caf) 2 ] Light Brown �260 84 5.48 [Mn(LH) 2 (caf) 2 ] Dark Orange �260 78 5.11 [Fe(LH) 2 (caf) 2 ] Black �260 72 5.50 Table-5Infrared and Raman data of the salicylaldazine (HL), caffeine and their complexes [M(LH)(caf)] ; M= Zn2+, Cd2+, Ni2+, Cu2+, Co2+, Mn2+, Fe2+; n=1,2; caf= caffeineSalicyladazine (H 2 L) Caffein29, 30Cd(LH)caf Zn(LH)caf Fe(LH)caf)Cu(LH)caf)2 Ni(LH)(caf)Co(LH)caf)Mn(LH)(caf) nnOH 3445 m,br - 3450 m,br 3450 m,br 3452 m,br 3452 m,br 3450 m,br 3450 m,br 3452 m,br nnCHar 3019 m (3000m) 3114m 3103w, 3045w, 3004w (3057w, 3011w) 3110w, 3040w, 3003w (3033w, 3006m) 3112w, 3053w, 3004w (3022w) 3113w, 3042w, 3002w (3070w, 3050w) 3100w, 3002w (3050w, 3015w) 3110w, 3040w, 3005w (3045w, 3011w) 3102w ,3050w, 3002w (3090m, 3055w) nnCHcaf - 2954w (2963w, 2957w) 2950w (2962w, 2944w) 2950w (2946w) 2984w, 2961w (2936w) 2953w (2955w) 2950w (2933m) 2982w, 2954w (2953w) 2946w (2953w) OH….N 2941w, 2709w2606w - - - - - - - - nnsC=O - 1702vs (1700s) 1698vs (1700w) 1696vs (1695m) 1695s (1704m) 1697vs (1700w) 1700vs (1697m) 1694s (1692m) 1697s (1697m) nnaC=O nnC=Ncaf - 1662s (1656s) 1650vs (1650m) 1654vs (1647s) 1648s (1652m) 1656vs (1650m) 1646s (1653) 1647s (1654m) 1653vs (1648m) nnsC=N/ nnC=Ccaf 1622vs (1624s) 1600m (1600m) 1610vs, 1580e (1620m, 1596m) 1610vs, 1575e (1617m) 1598s, 1573e (1594s) 1606vs, 1555e (1613s) 1600vs (1601s) 1598s, 1570m (1604s) 1593vs.1575e (1619m) nnaC=N (1594s) - (1560s) (1589s) (1551vs) (1581s) (1578m) (1585m) (1586s) nnC=C(ring)+ ddHCN + nnring imidazole+ nnring pyrimidine 1567s, 1479s (1552vs, 1490w, 1455s) 1551w (1550w) 1535m, 1458m (1537vs, 1464s) 1536m, 1457w (1548vs, 1493w, 1454s) 1538m, 1458m (1454s) 1534m, 1461m (1551s, 1452s) 1530m, 1458s (1533s, 1495m, 1470m) 1520s, 1458s (1531s, 1491m, 1443s) 1532m, 1468m (1548s, 1477m, 1450w) ddCH3 + 1443m, 1487m,1424m 1433m, 1434m, 1442s, 1436vs,131438s,1371435m, Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 4(10), 72-84, October (2014) Res. J. Chem. Sci. International Science Congress Association 82 nnC-N 1382m, 1300m (1430w,1384w) 1466m 1431m, (1470w, 1466w, 1403w) (1440m, 1398w) 1300m (1402w, 1377m) 1378w, 1300m (1402m, 1378w) 1380w (1398w,) 77w, 1300w (1403m, 1375w) 4w, 1300w (1410m) 1375m, 1351w, 1303m (1403m,1375m) nnring (imidazole) + ring (pyrimidine) - 1327w (1331w) 1318m (1325m) 1320m (1323m) 1321e (1320s) 1318m (1320m) 1316m (1323w) 1318m (1326m) 1325w (1323m) ddC-Oph 1328s (1322m) - 1356m (1325) 1354m (1330m) 1352m (1345s) 1343m (1350w) 1338m (1350w) 1340m (1353m) 1335m (1350m) ddOH 1280vs - 1280m ( 1243w) 1275m (1250m) 1275m (1252w) 1280m (1243w) 1275w (1250w) 1275w (1258m) 1275w (1252w) nnC-HPh+ ddCH caf 1238w, 1203s (1244m, 1210w) 1241vs (1251m, 1241m, 1215m) 1238m (1201w) 1240m (1203m) 1240m (1202w) 1240m (1208w) 1240m (1212m) 1240m (1219m) 1238m (1212w,1231s) (CH) + nnC-O - 1190m (1189m) 1186m (1150m) 1182m (1152m) 1198m (1152w) 1198m (1147m) 1190m (1150m) 1196m (1151m) 1198m (1153m) ddCH(ring) In plane bend 1162m,1152m 1118m, 1038m (1155w, 1118m, 1031m) (1131m, 1080w, 1020w) 1118w, 1025m (1151w, 1117w, 1023w) 1132w 1030m (1154m, 1102w) 1124w, 1050w, 1022m (1153w, 1118w, 1027m) 1128w, 1050w, 1030w (1152w, 1115w) 1123m, 1025m (1152w, 1121w) 1122w, 1043w, 1022w (1153m 1114m) 1131m, 1050w, 1025m (1145s, 1115s) nnN-N (1063s) - (1059s) (1061s) (1056m) (1060m) (1057w) (1054m) (1058m) (N-CH3) + ring (imidazole) - 974s (975m) 975m (960w) 975m (974m) 974m (950w) 974m 970m (974w) 970w (975m) 976m (972w) CH (ring) Out-of-plane bend + (N- CH3) 990m, 981m, 949w, 901m, 859w, 839w, 790m, 760vs, 739m (999m, 795w) 861m, 754m (925w, 850w) 955m, 935w, 901m, 865m, 798m, 784m, 760s (913w, 807w) 933w, 905w, 897w, 880w, 856w, 817w, 796w, 780w (992w, 876s, 848m, 801w) 923w, 903w, 877w, 856w, 830w, 794w, 780w, 758w (903w, 844w, 800w) 937m, 903m, 895w, 862m, 837w, 781m (795w) 921m, 895m, 855w, 781w, 760m (924w, 892w, 825w) 923w, 909w, 863w, 835w, 810w, 797w, 758m (931m, 873w, 850m, 802m) 924m, 858w, 826w, 792w, 758m (900m, 872w, 841w, 815s) ring (pyrimidine) + ring (imidazole) - 746s (745w, 700w) 744s (750w, 702w) 756s (753m, 707m) 742m (740w) 748s (748w, 702w) 742s (750w, 708w) 743s (742m, 702w) 742m (757m, 704w) CH In plane ring def 687m, 655w, 624w (655vw) - 670m, 644w (629w) 670w, 643w (655w) 680w, 661w, 644w, 631w (665w, 624w) 698w, 678w, 643w (680w, 645w) 680w, 641w (686w, 656w) 695w, 682w, 660w, 641w, 631w (647w) 678m, 643w (644m, 620s) ring - 610vs(6605m 608m(61608w 608w 606w 607w 606w Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 4(10), 72-84, October (2014) Res. J. Chem. Sci. International Science Congress Association 83 (imidazole) 13w) 2w) nnM-N - - 578m(575w) 580w(562w) 576w (568w) 590w (588w) 578w (585w) 575w (579w) 577w(583w) CH Out-of-plane ring def + ring pyrimidine 569m, 555w, 520w, 491w, 478w, 460w, 440m, 416w (550vw, 530w, 450vw, 420vw) 485w, 466w, 427w (444w) 543w, 495w, 476m, 466m, 458w, 442w, 417m (550w, 445w) 558w, 533w, 478w, 462w, 451w, 420w, 418w (551m, 480w, 447m, 413w) 561w, 541w, 498w, 478w, 464w, 450w, 415w (555w, 502w) 562w, 542w, 494w, 478w, 463w, 454w, 438w, 417w (556w, 534w, 443w) 540w, 492w, 476m, 460w, 406m (554w, 471w) 540w, 493w, 478w, 462w, 440w, 410w (550w, 524w, 475w) 540w, 495e, 477w, 466w, 458w, 440w , 416w (555w, 517m, 489m) ddCCN 510w - 506w (508w) 508w 505w 506w 505w 506w 508w nnM-O - - 438w (430w) 436w (432w) 437w (436w) 422w (418w) 438w (444w) 450w (432w) 425w(431w) References 1.Kolb V.M., Kuffel A. 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