New heteronuclear complexes of PdII–LnIII–PdII with Schiff base ligand: Synthesis, crystal structures and chemical properties

Starting from the N,N’-bis(2,3-dihydroxybenzylidene)-1,3-diaminopropane (H4L) the new cationic complexes with the formulae: [LnPd2(H2L)2(NO3)](NO3)Cl·mCH3OH·nH2O (where: Ln = Pr (1), Sm (2), Gd (3); m = 3, n = 3 (1, 3) and m = 2, n = 4 (2)) were synthesized and characterized by various methods (elemental analysis, XRF, FTIR, SCXRD, TG–DSC, TG–FTIR and magnetic measurements). The compounds 1–3 are isostructural heterometallic trinuclear units. The palladium(II) occupying the N2O2 cavity of the Schiff base ligand. The Ln(III) ions are surrounded by two Schiff base ligands. A chelating bidentate nitrate ion appears in their coordination sphere. They are solvates containing different amount of methanol and water molecules depending on the central ions. They crystallize in the monoclinic space group P21/c. The thermal decomposition of 1−3 in the air proceed stepwise. Heating of 1−3 in an inert environment leads to release mainly molecules of: H2O, MeOH, CO2, CO. Mixtures of PdO and Pr6O11/Sm2O3/Gd2O3, confirmed by XRD analysis, are the solid residue of thermal decomposition of 1−3 in the air. The magnetic measurements confirm the paramagnetic character of Ln(III) ions.