Rhodium(III) aqua ion salts of ambivalent self assembled superanion capsules

The self assembled superanionic capsule [{Na(+)subset of(18-crown-6)(OH2)(2 )}subset of{(p-sulfonatocalix[4]arene(4-))(2)}](7-) (X7-) forms a 1:1 cryst alline complex with dinuclear [Rh-2(mu-OH)(2)(H2O)(8)](4+) when the cation is treated with sodium p-sulfonatocalix[4]arene and 18-crown-6 at pH 2. The overall composition of the crystalline solid is [Rh-2(mu-OH)(2)(H2O)(8)][X + 3 H+]. 11.5H(2)O. Treatment of a complex mixture of polynuclear rhodium( III) aqua ions in perchloric acid with excess sodium p-sulfonatocalix[4]are ne and 18-crown-6 at pH 2, results in selective retrieval of the tri- and t etranuclear rhodium(III) species in a single 1:1 co-crystallised phase, iso lated as the hydrate salt with overall composition [Rh-3(mu-OH)(4)(H2O)(10) ][Rh-4(mu-OH)(6)(H2O)(12)][2 X + 3H(+)] [Na(H2O)(ClO4)](2). 27H(2)O. The tr i- and tetranuclear Rh cations both have a cyclic structure with mu-hydroxi de and terminal water ligands. Despite the differences in cation charge and size both complexes show the same arrangement of polynuclear cations and s uperanions although the trimer/tetramer complex shows additional coordinati on of a. second Na centre by the calixarenes. At pH 0.35 the reaction leads to the selective retrieval of the tetranuclear cation in the complex [Rh-4 (mu-OH)(6)(H2O)(12)][X + {X - 2 H2O} + 8 H+]. 33H(2)O, where a second type of dehydrated superanion is found, where the two sodium bound water molecul es have been replaced by O-centres of calixarene sulfonate groups, illustra ting the versatile nature of the superanion chemistry.