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|Type:||Artigo de periódico|
|Title:||Adducts Of Amides With Antimony And Bismuth Trichlorides: Synthesis, Characterization, And Thermochemistry|
|Abstract:||The adducts SbCl3·L [L = N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMA), and tetramethylurea (TMU)], MCl3·2L (M = Bi for L = DMF, DMA, and TMU; M = Sb for L = TMU), and BiCl3·3L (L = DMA and TMU) were isolated and characterized by melting points, elemental analysis, infrared spectroscopy, mass spectrometry, nuclear magnetic resonance spectroscopy, and conductometric measurements. The enthalpies of dissolution, ΔHθR, in acetone of adducts, trichlorides, and ligands at 298.15 K, for the reactions MCl3(s) + nL(l) = MCl3·nL(s,l) resulted in the following values (ΔHθR/kJ mol-1): SbCl3·DMF(l), -27.82 ± 0.15; SbCl3·DMA(l), -37.96 ± 0.16; SbCl3·TMU(s), -44.86 ± 0.27; SbCl3·2TMU(s), -76.96 ± 0.42; BiCl3·2DMF(s), -66.15 ± 0.61; BiCl3·2DMA(s), -82.36 ± 0.83; BiCl3·2TMU(s) -83.88 ± 0.83; BiCl3·3DMA(s), 93.85 ± 0.65; BiCl3·3TMU(s), -112.19 ± 0.98. From ΔHθR, the following enthalpies of formation of metal chlorides, ΔHθf(MCl3(s)) and ΔH⊖f(L(l)), were calculated for the same sequence of adducts [ΔHθf(s, 298.15 K)/kJ mol-1]: -649.2 ± 1.3, -698.3 ± 1.7, -681 ± 0.3, -967.7 ± 0.8, -924.0 ± 3.0, -1018.1 ± 3.8, -971.8 ± 1.3, -1307.9 ± 5.2, and -1254.5 ± 3.0. The standard enthalpies of reactions ΔHθM for MCl3(g) + nL(g) = MCl3·nL(s,l) and ΔHθD for MCl3·nL(s,l) = MCl3(s) + nL(g) have been calculated by means of thermochemical cycles, and the enthalpies of metal-oxygen bonds were estimated. The calorimetric data suggest that ΔHθM is the best parameter to characterize the adducts and showed the order BiCl3 > SbCl3 (acidity) and TMU > DMA > DMF (basicity). © 1981 American Chemical Society.|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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