METAL-COMPLEXES OF SALICYLHYDROXAMIC ACID AND O-ACETYLSALICYLHYDROXAMIC ACID

The salicylhydroxamic acid (H(2)Sha) complexes, Ni(HSha)(2) . 2H(2)O, Cu(HSha)(2) . 2H(2)O, Zn(HSha)(2) . 1.5H(2)O and Fe(Sha)(3) . 2H(2)O, in which the ligand is coordinated to the metal through the hydroxamat e group have been synthesised. Acetylation of salicylhydroxamic acid w ith acetyl chloride in pyridine gave O-acetylsalicylhydroxamic acid (H (2)Sha-OAc) in which the hydroxamate oxygen is acetylated and from whi ch the complexes Ni(HSha-OAc)(2) . H2O and Zn(Sha-OAc) were prepared. In the zinc complex the ligand is coordinated to the metal through the phenolate oxygen and the deprotonated nitrogen of the acetylhydroxami c group, the latter being an extremely rare type of coordination in th e case of this metal ion. Attempted preparation of iron(III) and coppe r(II) complexes resulted in deacetylation of the ligand and the format ion of salicylhydroxamate complexes. (C) 1997 Elsevier Science S.A.