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 aqu eous K2PdCl4 and K2PtCl4 solutions, respectively, because of formation of c omplex ion pairs where K+ was coordinated with the crown ether moiety while the platinides(II)were present in the paired anionic species. Sorption sto ichiometry and binding constants determined for the interaction of PDB18C6 with K2PdCl4 and K2PtCl4 were distinctive. On the basis of spectral charact eristics (electronic absorption and IR) obtained for the immobilized comple xes, Pt(II) was assumed to be sorbed as anion [PtCl4](2-) while Pd(II) form ed multinuclear species [PdnCl2n+2](2-). Within the complex ion pairs, Pd(I I), in contrast with Pt(II), may interact with the aromatic substituents of the immobilized DB18C6.