Tubelike Uranyl–Phenylenediacetate Assemblies from Screening of Ligand Isomers and Structure-Directing Counterions

Reaction of 1,2-, 1,3-, or 1,4-phenylenediacetic acids (1,2-, 1,3-, or 1,4-H2PDA) with uranyl ions under solvo-hydrothermal conditions and in the presence of [M(L)n]q+ cations, in which M = transition metal cation, L = 2,2′-bipyridine (bipy) or 1,10-phenanthroline (phen), n = 2 or 3, and q = 1 or 2, gave 10 complexes which have been crystallographically characterized. The diacetate ligands are bis-chelating and the uranyl cations are tris-chelated in all cases. [UO2(1,2-PDA)2Zn(phen)2]·2H2O (1) and [UO2(1,4-PDA)2Mn(bipy)2]·H2O (2) are heterometallic, neutral one-dimensional (1D) coordination polymers in which the carboxylate-coordinated 3d block metal cation is either decorating only (1) or participates in polymer building (2). [Zn(phen)3][(UO2)2(1,3-PDA)3] (3) and [Ni(phen)3][(UO2)2(1,4-PDA)3]·H2O (4), with separate counterions, crystallize as anionic two-dimensional (2D) networks, as does [Cu(bipy)2][H2NMe2][(UO2)2(1,4-PDA)3] (5), which displays parallel 2D interpenetration. The complex [Zn(phen)3][(UO2)2(1,2-PDA)3]·7H2O (6) crystallizes as a ladderlike, slightly inflated ribbon. The same topology is found in [Zn(bipy)3][(UO2)2(1,3-PDA)3] (7), but the larger separation between coordination sites and the coexistence of curved and divergent ligand conformations produce a tubelike assembly. An analogous but more regular and spacious tubular geometry is found in [M(bipy)3][(UO2)2(1,4-PDA)3], with M = Co (8) or Ni (9), and {Λ-[Ru(bipy)3]}[(UO2)2(1,4-PDA)3] (10). The disordered counterions in 8 and 9 are replaced by well-ordered, enantiomerically pure chiral counterions in 10. The tubular assemblies formed in 7–10 are characterized by an oblong section and the presence of gaps in the walls, which enable the inclusion of two rows of counterions in the cavity.