Structure of polynuclear palladium(ii) hydroxocomplexes formed upon alkaline hydrolysis of palladium(ii) chloride complexes

The hydrolysis and precipitation of Pd(II) in 0.6molkg−1 NaCl: A potentiometric, spectrophotometric, and EXAFS study

“…The Pd-Cl distance in the Pd(OH) 1.73 Cl 0.27 solid of 2.185 Å is 0.2-0.3 Å shorter than those of monomeric Pd(II)-chloride species measured in aqueous solutions (Valle and Ettorre, 1994;Hellquist et al, 1996;Caminiti et al, 1996Caminiti et al, , 1998 and calculated in the gas phase (Table 2; Bray et al, 1996;Deeth and Elding, 1996;Boily and Seward, 2005). It is however close to the EXAFS-derived value of 2.25 Å obtained by Troitskii et al (1995) on a similar material and most likely arises from the bridged coordination of chloride between two palladium atoms (Wyatt, 1966;Dressick et al, 1994), as illustrated in Fig. 6a.…”

“…Previous TEM, NMR and SAXS work by Troitskii et al (1993Troitskii et al ( , 1995Troitskii et al ( , 1996 in fact provided strong evidence for the formation of nano-size (15-40 Å ) hydrolysed palladium particles in aqueous solutions, as it will be discussed further in the following sections.…”

“…This is attributed to an axial O in the solid which is somehow suppressed in the presence of chloride. It could be possible that chloride affects the coiling pattern of the [Pd(OH) 1.72 Cl 0.28 ] n chains previously described by Troitskii et al (1993), Troitskii et al (1995Troitskii et al ( , 1996, an issue that warrants further investigation. The Pd-Cl distance in the Pd(OH) 1.73 Cl 0.27 solid of 2.185 Å is 0.2-0.3 Å shorter than those of monomeric Pd(II)-chloride species measured in aqueous solutions (Valle and Ettorre, 1994;Hellquist et al, 1996;Caminiti et al, 1996Caminiti et al, , 1998 and calculated in the gas phase (Table 2; Bray et al, 1996;Deeth and Elding, 1996;Boily and Seward, 2005).…”

“…Palladium(II) is one of the most hydrolysable metal ions (Baes and Mesmer, 1976) and its hydrolysis products have consequently been studied under a variety of conditions (Wyatt, 1966;Izatt et al, 1967;Kazakova and Ptitsyn, 1967;Nabivanets and Kalabina, 1970;Rund, 1970;Milić and Bugarčić, 1984;Mountain and Wood, 1988;Kump and Byrne, 1989;Wood et al, 1989Wood et al, , 1992Wood, 1991;Byrne and Kump, 1993;Tait and Janecky, 1993;Tait et al, 1991;Troitskii et al, 1993Troitskii et al, , 1995Troitskii et al, , 1996Dressick et al, 1994;Didillon et al, 1998;van Middlesworth and Wood, 1999;Byrne and Yao, 2000;Cosden and Byrne, 2003). Partially hydrolyzed Pd(II) species can crosslink and form larger polymeric/polynuclear units that are stable as coiled [Pd(OH) 2 ] n chains of about 20 Å in diameter (Troitskii et al, 1993(Troitskii et al, , 1995(Troitskii et al, , 1996.…”

“…Partially hydrolyzed Pd(II) species can crosslink and form larger polymeric/polynuclear units that are stable as coiled [Pd(OH) 2 ] n chains of about 20 Å in diameter (Troitskii et al, 1993(Troitskii et al, , 1995(Troitskii et al, , 1996. Evidence for such particles was provided by Transmission Electron 0016-7037/$ -see front matter Published by Elsevier Ltd.…”