Peculiarities of K2PdCl4 and K2PtCl4 complexation with polymer-supported dibenzo-18-crown-6

Dibenzo-18-crown-6 supported on a styrene-divinylbenzene copolymer matrix (PDB18C6) was found to be an efficient sorbent of Pd(II) and Pt(II) from aqueous K2PdCl4 and K2PtCl4 solutions, respectively, because of formation of complex ion pairs where K+ was coordinated with the crown ether moiety while the platinides(II)were present in the paired anionic species. Sorption stoichiometry and binding constants determined for the interaction of PDB18C6 with K2PdCl4 and K2PtCl4 were distinctive. On the basis of spectral characteristics (electronic absorption and IR) obtained for the immobilized complexes, Pt(II) was assumed to be sorbed as anion [PtCl4](2-) while Pd(II) formed multinuclear species [PdnCl2n+2](2-). Within the complex ion pairs, Pd(II), in contrast with Pt(II), may interact with the aromatic substituents of the immobilized DB18C6.