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 spectroscop y and by thermogravimetric (TG and DTA) analysis. The crystal structur e of diaquatris(maltolato)praseodynium(III) trihydrate is also reporte d. 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)-degr ees, gamma = 94.11(4)-degrees, V = 1177 angstrom3, Z = 2. The structur e was refined to R = 0.034 based on 3329 observed reflexions. The comp ound consists of [Pr(Ma)3(H2O)2] molecules in which the Pr atom is eig ht-coordinated. Three H2O molecules of crystallization are also presen t.