Synthesis and spectroscopic studies of new leucine acid derivative with their metal complexes.

A new ligand N-[(acetyl amino)-thioxo methyl]leucine(ATL) are synthesized by reaction of acetyl-isothio cyanate with leucine acid. The ligand is characterized by elemental analysis, FT-IR and NMR spectra, some transition metal complex of this ligand were prepared and characterized by FT-IR, UV-visible spectra, conductively measurements, magnatic suscpility, atomic absorption and determination of molar ration(M:L). from results obtained, the following formaula [M(ATL)2] where M+2 =(Mn, Fe, Co, Ni, Cu, Zn, Cd and Hg) and the proposed molecular structure for these complexes as tetrahedral geometry .


Introduction
Complexes of amino acids play an essential role for exploring various bio chemical processes or to remove metal toxicity from biological systems [1] Nasser and coworkers [2] reported the synthesis and characterization of Schiff base complexes derived from [2.acetyl pyridine] and leucine with Cu(II), Co(ІІ), Ni(II), Cr(III) and Fe(III). Shaesta and coworkers [3] study the determination of the formation constant of Cu(II), Zn(II), Cd(II), Hg(II) and Pb(II) with N-acetylcysteine by using potentialmetric method. the molar[4] enthalpies of formation of the crystalline form of bis(glycinate)lead(II), bis(DLalaninate)lead(II), bis(DL-valinate)lead(II), bis(DLvalinate)zinc(II) and bis(DL-valinate)cadmium(II) were determind. Safael and coworkers [5] were reported the synthesis and characterizion of glycine derivative of bis(phenol) amine ligand and its complexes with iron(III) and also [6] new βaminoacrylic acid Ni(II) complex has been developed and used for the synthesis of α-alkyl-β amino acids via alkylation with alkyl halides under operation ally convenient conditions. We have invstigated in this paper the preparation and properties of some new metal ion complexes with new ligand N-[(acetylamino)-thioxmethyl]leucine(ATL).

Results and Discussion
The physical properties of the ligand(ATL)with their metal complexes are given in table (1) the lower value of molar conductivity in DMSO, indicates the non electrolyte behavior of these complexes.

Infrared spectra
The characteristic vibrations and assignments of ligand(ATL)and their complexes as KBr disc are described in table (2). The spectrum of free ligand(ATL) fig(2) exhibited astrong band at(3332)cm-1 this could be attributed to υ(N-H) overlap with υ(OH). While the strong band at(1701)cm-1, which belong to υ(COO)asym and the other bands ν(OCO)sym and υ(C=S)were found at (1385) The yellow complex of Mn(ІІ) shows band at (35714)cm-1, which belongs to charge transfer and another band at (30211)cm-1 which is caused by the electronic transition 6A1→4T2(p) [16]. -

-[Cu(ATL)2] complex
The spectrum of deep-brown complex of Cu(ІІ) shows two bands at (30769)cm-1 and (27624)cm-1 which belongs to the charge transfer. The band found in the visible region at(14347)cm-1 was attributed to the electronic transition 2T2→2E [20].

Study of complexes formation in solution:
Complexes of ligand(ATL) with metal ions were studied in solution using ethanol as solvent in order to determine [M ∕ L] ratio in complexes follow molar ratio method [22] , Aseries of solutions were prepared having a constant concentration(10-3M) of metal ion and ligand. The [M ∕ L] ratio determined from the relationship between the absorption of the absorbed light and the mole ratio of [M ∕ L]. The results of complexes in ethanol suggest that the metal to ligand ratio was [1:2] for all complexes which were similar to that obtained from solid state study.