Compostos de adição entre iodetos de itrio e lantanídeos(III) e a N,N,N\ ,N\ - tetrametilmalonamida / N, N, N\ , N\ - tetramethylmalonamide adducts of lanthanide iodides

AUTOR(ES)

LilianRothschild Franco de Carvalho

FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

22/02/1979

RESUMO

Addition compounds of formula Lni3.xTMMA (x = 5 for Ln = La, Ce and x = 4 for Ln = Pr - Lu, Y) were prepared by reaction of N,N.N\ ,N\ -tetramethylmalonamide (TMMA) and lanthanide iodides in acetone. The crystalline adducts present the same, but fainter colors of the corresponding lanthanide ions; they are in general practically not hygroscopic and melt with decomposition between 200-250°. They are soluble in water, nitromethane, acetonitrile, slightly soluble in methanol, ethanol, nitrobenzene, acetone and practically insoluble in benzene, carbon tetrachloride and chloroform. The compounds were characterized by elemental analysis, infrared spectra, X-ray powder patterns, electrolytic molar conductance, visible spectra of neodymium, holmium and erbium in acetonitrile, absorption spectrum of the solid neodymium compound at different temperatures and emission spectrum of the solid europium compound at liquid nitrogen temperature. lnfrared spectra indicate that coordination of the ligand occurs through the carbonyl oxygens. X-ray patterns show four types of structures: the first contains the lanthanum and cerium compounds; the second the adducts for praseodymium to dysprosium, the third the holmium compound and the fourth type the adducts from erbium to lutecium and yttrium. Conductance data indicate a behaviour of 1:3 electrolytes in acetonitrile and nitromethane, and 1:2 electrolytes in methanol. The visible spectra of neodymium, holmium and erbium adducts in acetonitrile are not essentially modified at different concentrations. The nephelauxetic parameter, β, the covalency factor, b1/2 and the SINHA\ s parameter, δ, were determined from the neodymium spectrum. The values obtained show that the interaction between Nd3+ and the ligand is essentially electrostatic. The oscillator strenght was calculated from the neodymium spectrum in nitromethane solution and the value was compared with those obtained for other neodymium adducts. The number of bands and shape of the emission spectrum of the europium compound may suggest the D2d symmetry for the adducts of the same isomorphous series. A comparative study concerning absorption and emission spectra of the perchlorate, hexafluorphosphate, nitrate, isothiocyanate and chloride neodymium and europium adducts with TMMA was realized. The parameters, β, b1/2 and δ and the oscillator strenghts. P, were determined for the neodymium adducts. The emission spectra of the corresponding europium compounds were also determined. Suggestions concerning symmetry and geometry of the adducts are given.

ASSUNTO(S)

complexes complexos compostos de adição iodetos iodides Ítrio lantanídeos lanthanide n; n ; n - tetramethylmalonamide n;n ;n - tetrametilmalonamida síntese inorgânica

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