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|Type:||Artigo de periódico|
|Title:||Enthalpy Of Metal-ligand Interactions In Some Adducts Znx2·2l (x = Cl, Br; L = Ligand With O Or N As Electron Donor Atom)|
|Abstract:||The enthalpies of dissociation of ZnY bonds, D(ZnY), in adducts of the type ZnX2·2L (X = Cl, Br; L = ligand with O or N as donor atom) were previously estimated by means of the extrathermodynamic hypothesis. The present paper confirms these previous calculations by means of: (a) using a thermochemical cycle involving the dissolution of solid and gaseous zinc chloride in the ligands, i.e. N,N-dimethylactamide (dma) and pyridine (py). For ZnCl2·2dma and ZnCl2·2py, the values of D(ZnO) found were 147 ± 15 and 156 ± 15 kJ mol-1, respectively. These values are comparable to those obtained previously: 139 ± 15 and 153 ± 15 kJ mol-1, respectively. (b) Using the theory of Sanderson and the attribution of the bonding order leading to values of 146 ± 15 and 141 ± 15 kJ mol-1 for the same adducts. For the adducts ZnCl2·2tppo and ZnBr2·2tppo (tppo = triphenylphosphineoxide), the same value of 199 ± 15 kJ mol-1 was obtained for D(ZnO), whereas for the adduct ZnCl2·2pyo (pyo = pyridine-N-oxide), the D(ZnO) value 230 ± 15 kJ mol-1 was found. The values previously reported for these tppo and pyo adducts were 184 ± 15, 169 ± 15 and 232 ± 14 kJ mol-1, respectively. By means of another thermochemical cycle the enthalpy of sublimation of the adducts was also estimated, with values close to those reported previously. © 1994.|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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