Chain, network and framework formation in uranyl ion complexes with 1,1ʹ‐Biphenyl‐3,3ʹ,4,4ʹ‐tetracarboxylate
Résumé
1,1'-Biphenyl-3,3ʹ,4,4ʹ-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 ][UO 2 (bptc)(HCOO)]⋅2.5H 2 O ( 1 ) crystallizes as a monoperiodic coordination polymer in which the bptc 4– 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 [H 2 NMe 2 ] 2 [UO 2 (bptc)]⋅0.5H 2 O ( 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 H 2 NMe 2 + counterions being located between the undulating sheets. [PPh 4 ] 4 [(UO 2 ) 4 (bptc) 3 ]⋅6H 2 O ( 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 PPh 4 + 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.
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