Studies on Coördination Compounds. XV. Formation Constants for Chloride and Acetylacetonate Complexes of Palladium(II)

Abstract

The stepwise formation constants for the chloride complexes of palladium(II) have been determined from spectrophotometric measurements made at 21, 29.5 and 38°. The reaction between palladium(II) chloride and acetylacetone in aqueous solution has also been investigated, but from pH measurements at 20, 30 and 40°. The logarithm of the over-all formation constant for PdCU-2, estimated to be 15.8 at 25°, is observed to be of the same order of magnitude as that for PtCU-2 and HgCl,-2. The thermodynamic stability of bis-(acetylacetonato)-palladium(II) is greater than would be anticipated from considerations of the electronegativity and the second ionization potential of palladium.

Instrumental effects on in situ electrochemical STM studies: An investigation of a current surge induced Pd deposit on HOPG

“…This capacitance, one order of magnitude higher than that of the clean HOPG surface, is a combined contribution from the majority uncovered HOPG area and the small area covered by the surge deposit. This again indicates the adsorption of polar species such as Cl--rich chlorocomplexes of Pd2+ (Droll et al, 1957) on the surge-induced Pd deposit.…”

Selective Solvent Extraction of Various Metal Ions with Tris(2,6-dimethoxyphenyl)phosphine from Hydrochloric Acid Solutions

“…In a hydrochloric acid solution, these two metal ions have been found to exist as a mixture of di-, tri-and tetra-chloro metal complexes, the distribution of which depends on its concentration: the distribution of tetrachloro species increases with increasing the concentration of hydrochloric acid. 10 In extractions of palladium(II) and platinum(II) from a diluted hydrochloric acid, the present extractant …”

Palladium(II) chloride complexation: Spectrophotometric investigation in aqueous solutions from 5 to 125°C and theoretical insight into Pd-Cl and Pd-OH2 interactions

“…A number of sets of low temperature complexation constants for the monomeric PdCl r (H 2 O) 4-r 2-r species (r ϭ [0,4]) have already been proposed, mainly from potentiometric, solubility, and spectrophotometric studies (Sundaram and Sandell, 1955;Droll et al, 1957;Schukarev et al, 1961;Jørgensen, 1962;Burger and Dyrssen, 1963;Grinberg et al, 1963;Biryukov and Shlenskaya, 1964a;Biryukov and Shlenskaya, 1964b;Burger, 1964a;Burger, 1964b;Shlenskaya and Biryukov, 1964;Weed, 1964;Fasman et al, 1965;Levanda, 1968;Gel'fman and Kiseleva, 1969;Rittner et al, 1970;Kravtsov and Martynova, 1971;Elding, 1972b;Gulko and Schmuckler, 1973;Hsu et al, 1991;Tait et al, 1991;van Middlesworth and Wood, 1999). Spectrophotometric studies have, however, provided the most insight into palladium chloride complexation (e.g., Elding 1972a;Elding 1972b;Elding, 1973;Elding, 1975), given the possibility of detecting and quantifying the presence of different complexes by virtue of their different ligand-to-metal charge transfer spectra (Sundaram and Sandell, 1955;Droll et al, 1957;Schukarev et al, 1961;Jörgensen, 1962;Burger and Dyrssen, 1963;Biryukov and Shlenskaya, 1964a;Biryukov and Shlenskaya, 1964b;Burger, 1964a;Shlenskaya and Biryukov, 1964;Levanda, 1968;…”

“…Spectrophotometric studies have, however, provided the most insight into palladium chloride complexation (e.g., Elding 1972a;Elding 1972b;Elding, 1973;Elding, 1975), given the possibility of detecting and quantifying the presence of different complexes by virtue of their different ligand-to-metal charge transfer spectra (Sundaram and Sandell, 1955;Droll et al, 1957;Schukarev et al, 1961;Jörgensen, 1962;Burger and Dyrssen, 1963;Biryukov and Shlenskaya, 1964a;Biryukov and Shlenskaya, 1964b;Burger, 1964a;Shlenskaya and Biryukov, 1964;Levanda, 1968;Rittner et al, 1970;Elding, 1972b;Tait et al, 1991). Spectrophotometric measurements of the homogeneous hydrolysis of aqueous palladium(II) (Byrne and Yao, 2000;Boily and Seward 2002) have, for instance, clearly shown the formation constant of PdCl 3 OH 2-to be several orders of magnitude different than a value proposed by solubility measurements (van Middlesworth and Wood, 1999).…”

“…Some of these values have also served as a basis for extrapolations to high temperatures using isocoulombic approaches (Mountain and Wood, 1988;Ruaya, 1988;Wood et al, 1992) as well as the HKF equations of state (Helgeson et al, 1981;Sassani and Shock, 1990;Sassani and Shock, 1998). The only available experimental values above room temperature include those of the spectrophotometric studies of Droll et al (1957) (K 1-4 to 38°C), Shlenskaya and Biryukov (1964a) (K 4 to 45°C) and Tait et al (1991) (equivalence points to 90°C), as well as the solubility studies of Gammons (1995) (K 3 to 300°C) and van Middlesworth and Wood (1999) (␤ 4 , cumulative constant, up to 90°C). All of these studies show considerable scatter amongst themselves and with the aforementioned isocoulombic and HKF predictions.…”