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|Type:||Artigo de periódico|
|Title:||Heterocyclic Nitrogen-containing Electron-pair Donor Ligands: A Thermochemical Study Of Adducts With Zinc, Cadmium, And Mercury Chlorides|
|Abstract:||The standard enthalpies (ΔHR ⊖/kJ mol-1) of the reactions MCl2(s) + nL(s,l) → MCl2·nL(s) for ligands pyridine (py), 2,2′-bipyridine (bipy), and 1,10-phenanthroline (phen) were measured calorimetrically at 298.15 K, giving: ZnCl2·2py, -116.1 ± 1.0; CdCl2·py, -46.8 ± 0.5; HgCl2·py, -43.4 ± 0.4; ZnCl2·bipy, -82.9 ± 0.5; CdCl2·bipy, -53.9 ± 1.6; HgCl2·bipy, -37.7 ± 0.9; ZnCl2·phen, -83.5 ± 1.5; CdCl2·phen, -61.7 ± 1.7; and HgCl2·phen, -60.0 ± 1.6. The standard enthalpy of formation of bipy (216.4 ± 7.4 kJ mol-1) was derived by combustion calorimetry, while that for phen (354 kJ mol-1) was obtained by an estimative calculation method. The standard enthalpies of formation of the adducts were calculated, showing a decrease from zinc to mercury, and for each metal chloride the decrease py > bipy > phen was observed. The standard enthalpies of sublimation of the ligands bipy and phen were calculated, giving 67 and 65 kJ mol-1, respectively. The standard enthalpy of the metal-nitrogen bond, D̄ (M-N), was calculated by assuming the equivalence of each bond in a bidentate ligand. Values of D̄(M-N) for adducts of bidentate ligands were lower than the corresponding ones of pyridine.|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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