Palladium(II) saccharinate (sac) and thiosaccharinate (tsac) complexes with 2-aminopyridine (2-ampy), 2-acetylaminopyridine (2-aampy) and 2-acetylaminopyrimidine (2-aampym) co-ligands: X-ray crystal structures of trans-[Pd(sac)2(ampy)2] and solvatomorphs

Reactions of Na2PdCl4 with two equivalents of 2-aminopyridine (2-ampy), 2-acetylaminopyridine (2-aampy) or 2-acetylaminopyrimidine (2-aampym) afford complexes of the type trans-[PdCl2L2]. Further reaction with two equivalents of sodium saccharinate (Nasac) affords mixed-ligand complexes trans-[Pd(sac)2L2]. X-ray structures of trans-[Pd(sac)2(2-ampy)2] and two solvatomorphs of trans-[Pd(sac)2(2-aampy)2].S (S = CHCl3, thf) have been carried out. In all three, the saccharinate ligands coordinate in a monodentate fashion via the endocyclic amido group and all four ligands lie approximately perpendicular to the PdN4 plane. In trans-[Pd(sac)2(2-ampy)2] the metal ion lies on an inversion centre and consequently the ligands adopt a relative anti/anti-configuration, while in both solvatomorphs of trans-[Pd(sac)2(2-aampy)2] they adopt a syn/syn-configuration, the latter possibly resulting from intramolecular hydrogen bonding between the amine protons and the carbonyl oxygen. Reactions of trans-[PdCl2L2] with thiosaccharin (tsacH) are dependent upon the nature of the amine. Thus, with trans-[PdCl2(2-ampy)2] the desired mixed-ligand complex trans-[Pd(tsac)2(2-ampy)2] results, however with acetylamine complexes only the known homoleptic complex, [Pd(tsac)2], is isolated.