Coordination isomerism in salicylhydroxamate complexes of platinum(II) and palladium(II)

The syntheses of a range of platinum(II) and palladium(II) complexes containing salicylhydroxamate ligands are described. The ancillary ligands, together with the synthetic route, influence the coordination mode of the salicylhydroxamate ligand. Reaction of cis-[PtCl2 (PPh3)2] with salicylhydroxamic acid and trimethylamine in hot methanol gave O,Oʹ-bonded [Pt{OC(=NO)C6H4OH}(PPh3)2], but [PtCl2 (cod)](cod = cycloocta-1,5-diene) gave N,O-bonded [Pt{OC6H4C(O)NOH}(cod)]. Ligand substitution gives other N,O bonded complexes, including [Pt{OC6H4C(O)NOH}(PPh3)2]. Reaction of K2PtCl4 with 2 equiv. of EPh3(E = As or Sb), salicylhydroxamic acid and excess trimethylamine gives products whose structures depend on E; AsPh3 gives [Pt{OC(=NO)C6H4OH}(AsPh3)2], while SbPh3 gives [Pt{OC6H4C(O)NOH}(SbPh3)2].