PALLADIUM-DIHALIDE COMPLEXES WITH CARBONYL DONORS

Palladium halides react with 4H-pyran-4-one (P) and 2,6-dimethyl-4H-pyran-4-one (DMP) to yield [Pd(DMP)2X2] (X = Cl or Br), [Pd(P)2Cl2] and [Pd(P)Br2]n complexes which have been characterized by i.r. and proton n.m.r. spectroscopy. The thermal behaviour of the 4-pyrone adducts is correlated with that of N,N-dimethylformamide analogues, [Pd(DMF)2Cl2] and [Pd(DMF)Br2]n, the ligand coordinating ability following the order: DMP > P > DMF. On the basis of i.r. spectra, the [Pd(L)2Cl2] (L = DMP or P) adducts should have the usual trans configuration, whereas in both [Pd(P)Br2]n and [Pd(DMP)2Br2] a polymeric arrangement through bromine bridges should be present. The properties of the [Zn(P)2Cl2] and [Pt(DMP)2Cl2] complexes are also discusse