| Abstract: | Reaction of CeCl3·7H2O with Na2(oda) (oda = O(CH2CO2)22— oxydiacetate) in a 2:3 ratio gives the neutral cerium(III) complex Ce2(oda)3(H2O)3]·9H2O ( 1 ). Treatment of a 1:3 mixture of CeCl3·7H2O and H2oda in water with 4 molar equivalents of NaOH also gives 1 but, with a larger excess of NaOH, the tri‐sodium salt Na3Ce(oda)3]·9H2O ( 2 ) is isolated. Formation of a tri‐ammonium analogue of 2 can be achieved by neutralisation of an aqueous solution of CeCl3·7H2O and H2(oda) in a 1:3 ratio by NH4OH, giving (NH4)3Ce(oda)3]·7H2O ( 3 ). Use of the cerium(IV) reagent (NH4)2Ce(NO3)6] with Na2(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)3Na4(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 Na2(NO3)]+ pillared by Ce(oda)3]2— units, the connectivity arising by multidentate nitrate and carboxylate bridging. |
