Thermodynamics for complex formation between palladium(II) and oxalate
| Authors | |
|---|---|
| Year of publication | 2014 |
| Type | Article in Periodical |
| Magazine / Source | Dalton Transactions |
| MU Faculty or unit | |
| Citation | |
| Web | http://pubs.rsc.org/en/content/articlelanding/2014/dt/c4dt01062k |
| Doi | http://dx.doi.org/10.1039/c4dt01062k |
| Field | Inorganic chemistry |
| Keywords | palladium(II) ion; oxalate; metal complex formation; thermodynamics |
| Description | Complex formation between [Pd(H2O)4]2+ and oxalate (ox = C2O42-) has been studied spectrophoto-metrically in aqueous solution at variable temperature, ionic strength and pH. Thermodynamic parameters at 298.2 K and 1.00 M HClO4 ionic medium for the reaction [Pd(H2O)4]2+ + H2ox <-> [Pd(H2O)2(ox)] + H3O+ with equilibrium constant K1,H (in mol.dm-3) are log10K1,H = 3.38 ± 0.08, delta H0 = -33 +/- 3 kJ.mol-1, and deltaS0 = -48 +/- 11 J.K-1.mol-1, as determined from spectrophotometric equilibrium titrations at 15.0, 20.0, 25.0 and 31.0 degrees of Celsius. Thermodynamic overall stability constants Beta_n_0 (in (mol.dm-3)n) for [Pd(H2O)2(ox)] and [Pd(ox)2]2- at zero ionic strength and 298.2 K, defined as the equilibrium constants for the reaction Pd2+ + n ox2- <-> [Pd(ox)n]2-2n (water molecules omitted) are log10Beta_1 = 9.04 ± 0.06 and log10Beta_ = 13.1 +/- 0.3, respectively, calculated by use of Specific Ion Interaction Theory from spectrophotometric titrations with initial hydrogen ion concentrations of 1.00, 0.100 and 0.0100 mol.dm-3 and ionic strengths of 1.00, 2.00 or 3.00 mol.dm-3. The palladium complexes are significantly more stable than oxalato complexes of other divalent metals with higher co-ordination numbers as a result of the chelate effect. |
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