LANTHANIDE COMPLEXES WITH MALTOL - THE CRYSTAL-STRUCTURE OF DIAQUATRIS(MALTOLATO)PRASEODYMIUM(III) TRIHYDRATE

The reaction of lanthanide trichlorides with excess of maltol (HMa, 3-hydroxy-2-methyl-4H-pyran-4-one) in benzene or acetone yields the [Ln(HMa)3Cl3].nH2O (Ln = Pr, Nd or Eu; n = 0,1) adducts, whereas in water species as [Pr(Ma)3(H2O)2] or [Sm(Ma)2(OH)(H2O)2] have been isolated. The compounds have been characterized by IR and proton NMR spectroscopy and by thermogravimetric (TG and DTA) analysis. The crystal structure of diaquatris(maltolato)praseodynium(III) trihydrate is also reported. Crystals are triclinic, P1BAR, with a = 9.608(3), b = 11.318(3), c = 12.537(4) angstrom, alpha = 115.39(3)-degrees, beta = 103.08(8)-degrees, gamma = 94.11(4)-degrees, V = 1177 angstrom3, Z = 2. The structure was refined to R = 0.034 based on 3329 observed reflexions. The compound consists of [Pr(Ma)3(H2O)2] molecules in which the Pr atom is eight-coordinated. Three H2O molecules of crystallization are also present.