The properties and crystal structure of catena-poly[praseodymium(III)-hexaaqua-mu-L-threonine-kappa O-3,O ',O '']trichloride and catena-poly(pentaaqua-mu-L-threonine-kappa O-3,O ',O '') europium(III) and ytterbium(III) trichlorides

New complexes of L-threonine and lanthanides(III) of the formulae: [Pr(L-th r)(H2O)(6)]Cl-3 and [Ln(L-thr)(H2O)(5)]Cl-3, where Ln is Eu(III) and Yb(III ), were obtained. They were characterized by elemental, thermal and spectro scopic analyses, as well as the crystal structures were determined by X-ray diffraction method. The compounds are stable up to about 363 K but further healing leads to decomposition to oxychlorides and next to oxides. The com plex of Pr(III) crystallizes in the monoclinic P2(1) space group with cell dimensions a = 9.196(2), b = 19.877(4), c = 9.316(2) Angstrom, beta = 110.1 2(3)degrees, Z = 4. The complexes of Eu(III) and Yb(III) crystallize in the orthorhombic P2(1)2(1)2(1) space group with cell dimensions: a = 10.578(2) , 10.441(2) Angstrom; b = 7.417(2), 7.356(2) Angstrom; c = 18.815(4), 18.64 6(4) Angstrom, respectively. The complexes are polymeric chains, in which l anthanide(III) ions are linked by carboxylate bridge and L-threonine molecu les additionally coordinate to metal ions by the hydroxyl oxygen and six me mber rings are formed. The coordination number 9 for Pr(III) ion and 8 for the remaining lanthanides is achieved by coordination of six or five water molecules. The chloride anions are hydrogen bonded with the cationic part o f the complex.