Assembly of 3-D network structures containing oxydiacetate and CeIII or CeIV

Reaction of CeCl3.7H(2)O with Na-2(oda) (oda = O(CH2CO2)(2)(2-) oxydiacetate) in a 2:3 ratio gives the neutral cerium(III) complex [Ce-2(oda)(3)(H2O)(3)].9H(2)O (1). Treatment of a 1:3 mixture of CeCl3.7H(2)O and H(2)oda in water with 4 molar equivalents of NaOH also gives 1 but, with a larger excess of NaOH, the tri-sodium salt Na-3[Ce(oda)(3)].9H(2)O (2) is isolated. Formation of a tri-ammonium analogue of 2 can be achieved by neutralisation of an aqueous solution of CeCl3.7H(2)O and H-2(oda) in a 1:3 ratio by NH4OH, giving (NH4)(3)[Ce(oda)(3)].7H(2)O (3). Use of the cerium(IV) reagent (NH4)(2)[Ce(NO3)(6)] with Na-2(oda) results in reduction to cerium(III) under ambient conditions and isolation of 1. However, in the absence of light this reaction yields crystals of the novel cerium(IV) heterobimetallic [Ce(oda)(3)Na-4(NO3)(2)] (4). Each of these complexes exhibit a 3-D network structure having a common nine-coordinate [Ce(oda)(3)](n-) (n = 2 or 3) subunit, irrespective of the oxidation state of cerium. In 1, six [Ce(oda)(3)](3-) anions are connected, through bridging bidentate carboxylates, to a second Ce3+ site further coordinated by three water molecules. In contrast, the ammonium salt 2, displays isolated [Ce(oda)(3)](3-) anions, devoid of further carboxylate bonding, but enmeshed within a network of hydrogen-bonded NH4+ cations and water molecules. The remarkable structure of 4 consists of infinite 2-D sheets of [Na-2(NO3)](+) pillared by [Ce(oda)(3)](2-) units, the connectivity arising by multidentate nitrate and carboxylate bridging.