Abstract
A series of yttrium and terbium benzoate complexes have been prepared and structurally characterised as DMF or DMSO solvates, often also hydrated. The structures of these complexes vary considerably as a function of the steric bulk of the ligands and the degree of solvation. The smaller rare-earth elements, yttrium and terbium, are of comparable size and are observed to behave in a similar manner with several isomorphous complexes being formed and with the majority being dimeric. Six (μ-η1∶η1)2 bridged dimeric complexes of the form [Ln(O2CR)6(solv)2(H2O)2] (O2CR = benzoate, 3- and 4-methylbenzoate or 4-methoxybenzoate, solv = DMF or DMSO) have similar structures, despite a change in the ligand or the solvent of crystallisation. A different dimeric product containing four, rather than two, bridging ligands between the two metal atoms has been obtained with 4-nitrobenzoate, [Tb(4-NO2BA)3(DMF)(H2O)]2·4DMF, 9. A variety of polymeric products were synthesised that differ significantly from each other with a variety of benzoate binding modes and interesting intra- and inter-molecular hydrogen bonding motifs involving solvent molecules. Of particular interest are the solvent-free polymer [Y(2-MeBA)3]∞3, the yttrium polymer of 3-nitrobenzoate [{Y(3-NO2BA)3(DMSO)}{Y(3-NO2BA)3(H2O)2}] 8, containing two unique metal atoms in the repeating unit, and two polymers (8 and 10, {[Ln(4-NO2BA)3(DMSO)(H2O)2]·DMSO}∞ (Ln = Tb (10b), Y (10a))) that incorporate η1 benzoate ligands.