Assembly of 3‐D Network Structures Containing Oxydiacetate and Ce III or Ce IV

Reaction of CeCl 3 ·7H 2 O with Na 2 (oda) (oda = O(CH 2 CO 2 ) 2 2— oxydiacetate) in a 2:3 ratio gives the neutral cerium(III) complex [Ce 2 (oda) 3 (H 2 O) 3 ]·9H 2 O ( 1 ). Treatment of a 1:3 mixture of CeCl 3 ·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 CeCl 3 ·7H 2 O and H 2 (oda) in a 1:3 ratio by NH 4 OH, giving (NH 4 ) 3 [Ce(oda) 3 ]·7H 2 O ( 3 ). Use of the cerium(IV) reagent (NH 4 ) 2 [Ce(NO 3 ) 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 (NO 3 ) 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 Ce 3+ 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 NH 4 + cations and water molecules. The remarkable structure of 4 consists of infinite 2‐D sheets of [Na 2 (NO 3 )] + pillared by [Ce(oda) 3 ] 2— units, the connectivity arising by multidentate nitrate and carboxylate bridging.