Structural variations in terbium(III) complexes with 1,3-adamantanedicarboxylate and diverse co-ligands

Abstract

Terbium nitrate was reacted with 1,3-adamantanedicarboxylic acid (LH2) under solvo-hydrothermal conditions with either N,N-dimethylformamide (DMF) or N,N-dimethylacetamide (DMA) as organic solvents. Hydrolysation of the latter co-solvents resulted in the formation of formate or acetate ions, which are present as co-ligands in the 1D coordination polymer [Tb(L)(HCOO)(H2O)2] (1) and the 2D assembly [Tb(L)(CH3COO)(H2O)] (2). The increase in dimensionality in the latter arises from the higher connectivity provided by acetate versus formate, the L2− ligand being bis-chelating in both cases. The complex [Tb2(L)3(H2O)5][Tb2(L)3(H2O)4]·3H2O (3), another 1D species, crystallizes alongside crystals of 2. Further addition of cucurbit[6]uril (CB6), with DMF as co-solvent, gave the two complexes [Tb2(L)2(CB6)(H2O)6](NO3)2·6H2O (4) and [H2NMe2]2[Tb(L)(HCOO)2]2·CB6·3H2O (5). Complex 4 crystallizes as a 3D framework in which Tb(L)+ chains are connected by tetradentate CB6 molecules, while 5 unites a carboxylate-bridged anionic 2D planar assembly and layers of CB6 molecules with counter-cations held at both portals.