Alkylammonium Hexachlorometalates. 5.(1) Bis(1,6-diammoniohexane) Tetraaquahydrogen(1+) Hexachlororhodate(III) Dichloride, [H(3)N(CH(2))(6)NH(3)](2)[H(9)O(4)][RhCl(6)]Cl(2): Chain-like [H(9)O(4)](+) Ions Enclosed in the Cavities of a Complex Organic-Inorganic Framework.

[H3N(CH2)6NH3]2[H9O4][RhCl6]Cl2, obtained from 1,6-diaminohexane and rhodium trichloride in 12 M hydrochloric acid, has been shown by X-ray crystallography to contain chain-like [H9O4]+ ions in the cavities of a complex organic−inorganic framework built up by 1,6-diammoniohexane, hexachlororhodate(3−), and chloride ions. In view of crystal engineering the diammoniohexane ions act as “intelligent” building blocks, because their conformational flexibility enables them to take part in the formation of cavities with exactly the right lengths for the inclusion of the [H9O4]+.