Synthesis of several cyclopalladated biacetylmonoxime arylhydrazones

Palladium(II) complexes of biacetylmonoxime arylhydrazones (HL, aryl = phenyl, o-, m-, and p-tolyl, p-chloro- and p-nitrophenyl) and biacetylmonoxime N′-methyl-phenylhydrazone (HL′) have been prepared and characterized. The hydrazomines, HL and HL′, are coordinated through oxime- and hydrazone-nitrogen atoms as a bidentate ligand in the complexes PdX₂(HL or HL′)] (X = halogen atom) formed under neutral conditions. Under basic conditions the deprotonated complexes PdX(L or L′)] are obtained. Deprotonation occurs at the oxime group of HL′ and the ligand remains coordinated through oxime- and hydrazone-nitrogen atoms. The other hydrazoximes (HL) are cyclopalladated at the ortho position of the benzene rings and act as an NNC terdentate ligand in the deprotonated complexes PdXL].