Synthesis and Characterization of Fe (II), Co (II), Ni (II), Cu (II), Cd (II) Mono-Complexes with

Mannich bases have rececived great attention in recent years because of their proven antimalarial, antifungal and anticancer activities, coordination certain metal ions to them have interested use in synthesizing and studying structural aspects of metal complexes with oxygen and nitrogen donor ligands. The chelate ligand 4-hydroxy-3-(4'-morpholinyl methyl) quinoline was prepared by condensation of the formaldehyde with morpholine and 4-hydroxyquinoline in ethanol. A methanolic solution of the prepared ligand was reacted with a methanolic solution containing metal ions Fe (II), Co (II), Ni (II), Cu (II), Cd (II) to give metal complexes. The reaction of Fe (II), Co (II), Ni (II), Cd (II) ions with chelate ligand gave the mono-nuclear tetrahedral complexes, and mono-nuclear square planar complex with Cu (II). Their molecular structures were studied by FTIR, 1 H-NMR and UV-Visible spectra, atomic absorption technique, elemental analysis have been performed using CHN, magnetic susceptibility and conductivity measurements.


Introduction
The aminoalkylation of aromatic substrates by the mannich reaction is of considerable importance for the synthesis and modification of biologically active compounds, the reaction pathways of the mannich reaction depend on the nucleophilicity of substrate and the pH of reaction medium (1)(2)(3)(4).The reaction of these ligands with some transition metal ions gave a great importance in coordination chemistry, because of their application in pharmaceutical, industrial and analytical aspects (5)(6)(7)(8).In recent years mannich bases have attracted considerable attention due to formation of stable chelates with

Experimental Chemicals:
All chemicals used in this work were reagent grade (BDH/Aldrich).The purity of the mannich base ligand and its complexes were checked by thin layer chromatography (TLC) was carried out using fertig fallen precoated sheets type poly gram silica gel and the plates were developed with iodine vapour.

Instrumentation:
Melting points were recorded by using Gallenkamp M.F.B. 600.01 of melting point apparatus.Infrared spectra were recorded as Csl discs using FTIR 8300 Shimadzu.UV-Visible spectra were measured using Shimadzu UV-Vis 160A Ultra-violet spectrophotometer in the range (200-1100nm).
The metal percent in the prepared complexes were determined using Shimadzu 680 cc-flame.Elemental analysis C.H.N were performed using Carlo Erba 1106 elemental analyzer.Proton nuclear magnetic resonance analyses spectra were recorded using a Varian Unity plus (300MHz spectrometer) using CDCl 3 as a solvent and tetramethylsilane as internal reference.Magnetic susceptibility for the prepared complexes were obtained at room temperature using magnetic susceptibility balance Johnson Mattey catalytic system division and molar conductivity measurements were carried out at room temperature at the concentration 10 -3 M using corning conductivity meter 220.

Preparation of the Mannich Base Ligand:
To a solution of 4-hydroxyquinoline (0.1 mole) and formaldehyde (0.1 mole) in an absolute ethanol (15 ml) was added the morpholine (0.1 mole) at room temperature.
Then, the resulting mixture was heated at reflux for 20 hours.After cooling, yellow precipitate was collected by filteration, washed several times with ethanol and dried under vacuum.The yellow fine powder product was identified by FTIR spectroscopy and TLC technique.The suggested mechanism of mannich base ligand is as follows:-

Results and Discussion
The physical properties and analytical data of the ligand Q with their metal complexes (M1-M5) are given in Table 1.The stoichiometry of the ligand and its complexes were confirmed by their C.H.N. analysis.The elemental analysis of the ligand and its complexes show good support with the proposed structures.The lower values of molar conductivity in DMF as a solvent at concentration 10 -3 M at room temperature 25°C, indicates the non-electrolyte behavior of these complexes,these values suggest that no anions present outside  Table 2

Infrared Spectra
Infrared Spectra of Free Ligand(Q): The characteristic vibrations and assignments of ligand (Q) and their complexes as (M1-M5) are described in Table 3, Ligand spectrum showed that some changes appeared on comparision with the initial materials spectra ((13a,b), 14, 8):- (morpholine) at 3320cm -. 3. Stretching vibration of hydroxyl group (phenolic) appeared at 3458cm -in the spectrum of 4-hydroxyquinoline, was shifted to lower frequency by 4cm -in the spectrum of ligand due to the resonance with aromatic systems and strong band was found at 1252cm -belong to the (C-O) (phenolic).4. The FTIR spectrum of formaldehyde, showed absorption bands at 1720 and 2830-2695 cm -region assigned to (C=O)and ((C-H) two moderately intense bands) , respectively disappeared in the spectrum of ligand.5.The carbon-carbon stretching vibration within the ring absorbed at 1581 and 1518cm -regions, imine group C=N stretch showed at 1623 cm -, weak band of aromatic C-H stretching vibration at 3063cm -was observed.6.Two bands appeared at 1157 and 1116cm -which could be due to ring C-H in-plane bending and the band 788cm -which could be due to ring C-H outplane bending frequency, the position of these three bands was confirmed by comparing the spectra of formaldehyde and 4-hydroxyquinoline (ortho substitution of quinoline ring).*:stretching vibrations,δ:bending vibrations.

Infrared Spectra of Complexes (M1-M5):
The disappearing of band for (OH) vibration in the spectra of complexes is indicating the coordination of phenolic oxygen with metal ions, the spectra bands of complexes at 1623cm -were characterized for the imine group which didn't suffer a shift.Thus, it is suggested that the C=N group is not coordinated to the metal ion.The bands due to (C-O) phenolic group and (CH 2 -N) aminomethyl group were shifted to a lower frequencies by (26-134)cm -and (4-54)cm -, respectively, therefore the ligand (Q) behave as a bidentate coordinating with metal ion through oxygen of hydroxyl group and aminomethyl group.The appearance of new weak bands in the range of (410-464)cm -and (455-550) which was attributed to the (M-O) and (M-N), respectively (15,16).

Table 3:
The characteristic bands of infrared spectra of (Q)and (M1-M5)complexes.The electronic spectra of the prepared ligand (Q) in DMF solvent and their complexes were recodes in Table 4, the spectrum of (Q) showed a strong band at (330nm) may be attributed to  → * electronic transition and the other band appearing at (385 nm) could be assigned to n → * electronic transition (17,18).

Electronic Spectra of Complexes (M1-M5):
The electronic spectra of the prepared complexes showed different absorption from that of the free ligand, some of these bands was shifted to higher wavelength than the corresponding bands in the ligand.

M1-complex
The dark green complex of Fe (II) showed band at (335nm) which belong to  → * and another band at (455nm) which caused by the electronic transition 5 Eg → 5 T 2 g.

M2-complex
The electronic spectrum of Co(II) showed band at (351nm) which belong to   * transition and two bands at (630and 715 nm) which assigned to 4 A 2 (F)  4 T 1 (F) and 4 A 2 (F)  4 T 1 (p) transitions, respectively in tetrahedral geometry.

M3-complex
Ni (II) complex assigned to the transition 3 T 1 (F)  3 T 1 (p) at (428nm) and another band at (337nm) may be due to   *transition.

M4-complex
Spectrum of green Cu (II) complex showed abroad band at (620 nm) which may be assigned to 2 Eg  2 T 2 g transition.The band at (390nm) may due to n  * transition, Cu (II) ion in the present complex showed square planar geometry.M5-complex Cd (II) complex was diamagnetic as expected for d 10 ions, so that no (d-d) transition can be expected in the visible region.

Magnetic Properties
The experimental magnetic moment for each metal complexes is listed in Table5.The magnetic properties are due to the presence of unpaired electrons in the partially filled d-orbital in the outer shell of transition metals.These magnetic properties give an idea about the electronic state of the metal ion in the complex.The magnetic moment of Fe +2 and Co +2 were found to be 5.3B.M. and 4.5B.M. respectively, which gave a good agreement for tetrahedral structures (19,20).The eff value for Ni +2 complex 2.5 B.M., this value refers to regular tetrahedral structure.The eff value of Cu +2 complex was found to be 1.9B.M. lead to square planar structure.Finally, Cd +2 complex was diamagnetic as expected for d 10 ions (17).

Proton Nuclear Magnetic Resonance:
The 1 H-NMR data of the compounds are presented in Table 6. 1 H-NMR spectrum for free ligand (Q) it can be conclude that the aminomethyl group is and absence of N-H hydrogen resonance of the secondary amine (morpholine) at δ1.9 ppm .2.51 (t, 4H) for H-a, 3.50 (S, 2H) for H-c (aminomethyl) protons, 3.64 (t, 4H) for H-b, 7.34 (m, 1H) ,7.61 (m, 2H) and 8.38 (m, 1H) for H-d and 8.03 (S, 1H) which assigned to OH group.(13 a,b) The chemical shift observed for the OH proton in the Q (8.03 ppm) was not observed in any of the (M1-M5) complexes.This confirms the bonding of oxygen to the metal ions.The multiplets of aomatic quinoline ring appeared within the range  (7.34-8.38 ppm) and they were not affected by chelation, the protons of the -CH 2 (aminomethyl) group shifted to higher field (21), the 1 H-NMR spectral data gave additional support for the composition of the complexes.
According to the results obtained from the chemical shifts spectrum, the molecular structure of the ligand can be suggested.

Table 1 :
. Physical characteristics and analytical data for ligand (Q) and its metal complexes.

Table 2 :
Symbols, molecular formula and names of the prepared ligand and complexes.