Synthesis and Characterization of [2-(carboxy methylene-amino)-phenyl imino] acetic acid (L) and its some metal complexes

New Schiff base, namely [2-(carboxy methylene-amino)-phenyl imino] acetic acid (L) and its some metal complexes [LCo.2H 2 O], [LNi.2H 2 O], [LCu].3H 2 O, [LCd.2H 2 O], [LHg.2H 2 O] and [LPb.2H 2 O], were reported and characterized by elemental analysis, metal content, spectroscopic methods, magnetic moments and conductivity measurements, it is found that the geometrical structures of these complexes are octahedral [Co(II), Ni(II), Cd(II), Hg(II), Pb(II) and square planar Cu(II).The complexes have been found to posses 1:1 (M:L) stoichiometry


Introduction
N-substituted imines, also known as Schiff bases, have been used extensively as ligands in the field of coordination chemistry, furthermore the Schiff bases are very important tools for the inorganic chemists as these are widely used to design molecular ferromagnets, in catalysis, in biological modeling applications, as liquid crystals and as heterogeneous catalysts [1,2].Glyoxilic acid and its derivatives play important roles in natural processes, participating in glyoxylate cycle which functions in plants and in some microorganisms [3].Physical-chemical study of complexation of glyoxilic acid aroyl hydrazones with Cu(I) in solution and solid phase is reported [4].In continuation of earlier work [5], we report Schiff base derived by the condensation of o-phenylenediamine with glyoxylic acid (1:2) and its metal complexes.

Materials and Methods
All chemicals were purchased from BDH, and used without further purifications.Instrumentation 1. FTIR spectra were recorded in KBr on Shimadzu-8300 Spectrophotometer in the range of (4000-400 cm -1 ). 2. The electronic spectra in H 2 O were recorded using the UV-Visible spectrophotometer type (spectra 190-900 nm) CECIL, England, with quartz cell of (1 cm) path length.The physical properties for synthesized ligand (L) and its complexes are shown in Table (1).

Results and Discussion
The Schiff base (L) was synthesized in one step.The structure of (L) was checked and confirmed by elemental analyses data which are in good agreement with proposed formula C 10 H 8 N 2 O 4 .The 1 H-NMR illustrated in Fig. (1) and Table (2a) is complicated multiplets corresponding to aromatic four protons at 7.37-7.79ppm.

The IR, UV spectral and magnetic moments of complexes
Elemental analysis with metal analysis (A.A) compatible with the formula (C 10 H 6 N 2 O 4 ) M. nH 2 O where (n=2 or 3).
The bonding of the synthesized ligand (L) to metal ions was investigated by comparing FT-IR spectra of complexes with the free ligand (L).Some important absorption bands, and their assignments are given in Table (3) and Fig. (7).
The spectra of these complexes exhibited a broad band around (3363-3120) cm -1 assigned to water [8] (OH) associated with the complexes.
The band attributed to HC=N shifted to low frequencies by (71-46) cm -1 Table (3), supporting the idea that the ligand coordinate through the imine nitrogen [10][11].
New bands are found in the spectra of the complexes in the regions (540-489) cm -1 which are assigned to (M -O) mode [7].
Therefore from IR spectra, it is concluded that the ligand behave as anion tetradentate and bind to the metal ions via the two imine N and two carboxylate O.
The magnetic susceptibility measurement for the solid Co(II) complex is (4.90)B.M. Table (1) also is indicative of four unpaired electron per Co(II) ion suggesting consistency with its octahedral environment.
The magnetic susceptibility measurement of Cu(II) complex is (1.90)B.M., which suggests the presence of one unpaired electron with square planar configuration.
The spectra of the Cd, Hg and Pb exhibited charge transfer bands only which is a common phenomenon for metal complexes, where d-d transitions are excluded [21].
According to the elemental analysis Table (1) and FT-IR spectra, the structures of these complexes can be suggested octahedral [22] except Cu(II) complex is square planar.

Molar ratio
The complexes of the ligand (L) with selected ions(Cu +2 , Cd +2 ) were studied in solution using water as solvents, in order to determine (M:L) ratio in the prepared complexes, following molar ratio method [23].
A series of solutions were prepared having a constant concentration (C) 10 -3 M of the hydrated metal salts and the ligand (L).The (M:L) ratio was determined from the relationship between the absorption of the observed light and mole ratio (M:L) found to be (1:1).The result of complexes formation in solution are show in Table (5)(6)(7)(8), Fig. (9)(10).

Conclusion:
The

13 C
-NMR is shown in Fig.(2) and Table( ) k f = stability constant  = decomposition Degree M = metal ion L = The ligand [ ] = concentration As = The absorption of the equivalent point of mole ratio Am = The maximum absorption of the mole ratio C = The complex concentration (mole.L -1 ).Δ G = -2.303RT Log K. R = 8.303 T = 273 + 25 = 298 Molar conductivity for the complexes of the ligand (L)