Synthesis, Reactivity, and Structure of [H(13)O(6)][PtCl(5)(H(4)O(2))].2(18-cr-6): A Crown Ether Complex of a Pentachloroaquaplatinic Acid with an [H(13)O(6)](+) Cation in a Cage of Three Crown Ether Molecules.

An aqueous solution of H(2)[PtCl(6)].6 H(2)O reacts with crown ether 18-crown-6 to give [H(13)O(6)][PtCl(5)(H(4)O(2))]. 2(18-cr-6)(1) (1) and (H(3)O)(2)[PtCl(6)].2(18-cr-6) (2a). In the presence of HCl, only 2a is formed; in an analogous manner, (H(3)O)(2)[PtCl(6)].2(15-cr-5).2 H(2)O (2b) and (H(3)O)(2)[PtCl(6)].2(DCH-18-cr-6)(1) (2c) were obtained. 1 is gradually decomposed in water to give [PtCl(4)(H(2)O)(2)].(18-cr-6).2H(2)O (3). 1-3 were characterized by microanalysis and IR and NMR spectroscopy ((1)H, (13)C, (195)Pt). The X-ray structure analysis of 1 (orange needles; space group P2(1)2(1)2(1), a = 7.938(1) Å, b = 15.691(2) Å, c = 34.861(4) Å; Z = 4) shows an anionic entity [PtCl(5)(H(4)O(2))](-) and a cationic entity [H(13)O(6)](+) which are separated by a crown ether molecule 18-cr-6. The [H(13)O(6)](+) cations exhibit the structure [H(3)O(H(4)O(2))(2)(H(2)O)](+) and are also separated by crown ether molecules in such a way that the crystal is threaded by chains built up of 18-cr-6/[H(13)O(6)](+) units at which the 18-cr-6/[PtCl(5)(H(4)O(2))](-) moieties are fixed as lateral branches. Thus, the cations [H(13)O(6)](+) are embedded in three crown ether molecules. All terminal hydrogens are involved in hydrogen bridges to oxygen atoms of the crown ether molecules. The O(w).O(cr) distances are distinctly longer in the mean than the O(w).O(w) distances within the [H(13)O(6)](+) moiety.