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51.
The complexes of yttrium and heavy lanthanides with 3,4-dimethoxybenzoic acid of the formula: Ln(C9 H9 O4 )3 ×n H2 O, where Ln =Y(III), Tb(III), Dy(III), Ho(III), Er(III), Tm(III), Yb(III) and Lu(III), and n =4 for Tb(III), Dy(III), n =3 for Ho(III), and n =0 for Er(III), Tm(III), Yb(III), Lu(III) and Y(III) have been prepared and characterized by elemental analysis, IR spectroscopy,
thermogravimetric and magnetic studies and X-ray diffraction measurements. The complexes have colours typical of Ln3+ ions (Ho - cream, Tb, Dy, Yb, Lu, Y - white, Er - salmon). The carboxylate group in these complexes is a symmetrical, bidentate,
chelating ligand. They are crystalline compounds characterized by various symmetry. On heating in air to 1273 K the hydrated
3,4-dimethoxybenzoates decompose in two steps while those of anhydrous only in one stage. The tetrahydrates of Tb and Dy and
trihydrate of Ho 3,4-dimethoxybenzoates are firstly dehydrated to form anhydrous salts that next are decomposed to the oxides
of the respective metals. The complexes of Er, Tm, Yb, Lu and Y are directly decomposed to the oxides of the appropriate elements.
The solubility in water at 293 K for yttrium and heavy lanthanides is in the order of 10-4 -10-3 mol dm-3 . The magnetic moments of the complexes were determined over the range 77–298 K. They obey the Curie-Weiss law. The values
of μeff calculated for all compounds are close to those obtained for Ln3+ by Hund and van Vleck. The results show that there is no influence of the ligand field on 4f electrons of lanthanide ions
in these polycrystalline compounds and 4f electrons do not take part in the formation of M-O bonding.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献