Ada protein use in repairs methyl phosphotriesters in DNA by direct,irreversible transfer of the methyl groupto one of its cysteines, Cys69.This methyl transfer results in an irreversible loss of repair activity,So,the purpose of our study design and synthesis of polydentate metal(II) complexes, which structurally and functionally mimic the active site of sulfur-containing enzymes, and study of their activities toward the methylation reactions using methyl iodide as methylating agent. Consequently these metal(II) model complexes were used as potential bioinorganic catalysts to yield insight...