Termoquimica de quelatos de dialquilditiocarbamatos envolvendo fosforo, arsenio, antimonio e bismuto trivalente : alguns aspectos termoquimicos de alcoxidos e tris (dietilamido) de arsenio (III)

AUTOR(ES)
DATA DE PUBLICAÇÃO

1986

RESUMO

From the interaction of MCl (M = P, As, Sb, Bi) with dialkylammonium dialkyldithiocarbamate salts, the enthalpies of reaction in condensaded phase were determined: MCl(s,l) + 3 (R2NH2)(S2CNR2) (s) = M(S2CNR2)(s) + 3R2NH2Cl(s); DrHm (R=C2H5 ou n-C4H9) which enable in to obtain the enthalpies of formation of the chelates in the solid phase. Through differential scanning calorimetry or estimative methods, the enthalpies of sublimation were determined and consequently the enthalpies of formation of the chelates in the gaseous phase. From these data the mean enthalpy of the M-S bond were obtained by considering the homolytic as well as the heterolytic breaking, which showed that these thermochemical parameters decrease from P to Bi. The results show that the nature of the alkyl radical does not affect the parameters, which seem to be dependent on the charateristcs of the metaIs. Similar studies were made for the reactions: As(NEt2)3(l) + 3ROH(l) = As(OR)3(l) + 3HNEt2(l); DrHm e As(NEt2)3(l) + 3CS2(l) = As(S2CNEt2)3(s); DrHm to obtain the mean enthalpies of the As-0 and As-N bonds. The data show that: D(As-0) >D(As-N) >D(As-S).

ASSUNTO(S)

termodinamica termoquimica fisico-quimica

ACESSO AO ARTIGO

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