Chain, Network and Framework Formation in Uranyl Ion Complexes with 1,1′‐Biphenyl‐3,3′,4,4′‐Tetracarboxylate

Abstract

Abstract1,1′‐Biphenyl‐3,3′,4,4′‐tetracarboxylic acid dianhydride has been reacted with uranyl nitrate under solvo‐hydrothermal conditions and in the presence of different counterions to give three complexes of varying periodicity. [Co(en)3]‐ [UO2(bptc)(HCOO)] ⋅ 2.5H2O (1) crystallizes as a monoperiodic coordination polymer in which the bptc4− ligand is exclusively bound through formation of two 7‐membered chelate rings. The [Co(en)3]3+ counterion is essentially a hydrogen bond donor, forming 15 hydrogen bonds with carboxylate and water oxygen atoms. In [H2NMe2]2[UO2(bptc)] ⋅ 0.5H2O (2), half the ligand forms a 7‐membered chelate ring, and the other half bridges two uranium atoms, resulting in the formation of a diperiodic network with hcb topology, the H2NMe2+ counterions being located between the undulating sheets. [PPh4]4[(UO2)4(bptc)3] ⋅ 6H2O (3) contains a mixture of ligands forming either four 4‐membered or two 7‐membered chelate rings, the latter with further bridging, which gives a triperiodic framework displaying large channels, each of which contains two rows of PPh4+ counterions. These results are compared to those of previous studies with this ligand, and of similar studies of phthalate complexes of uranyl ion, in particular in relation to 7‐membered chelate ring formation.