One-dimensional chain structures of hexanuclear uranium(iv) clusters bridged by formate ligands.

Three one-dimensional chain structures of uranium(iv) hexanuclear clusters have been synthesized under hydrothermal/solvothermal conditions. Crystallographic studies disclose that the structures of [U 6 O 4 (OH) 4 (HCOO) 12 (H 2 O)]·3H 2 O (1a), [U 6 O 4 (OH) 4 (HCOO) 12 (HCOOH)(H 2 O)]·3H 2 O (1b) and (H 6 C 5 N) 2 [U 6 O 4 (OH) 4 (HCOO) 14 (H 5 C 5 N)] (2) contain a U(iv) hexanulear core [U 6 ( μ 3 -OH) 4 ( μ 3 -O) 4 ] 12+ which is decorated by terminal HCOO - ligands and water (1a, 1b), HCOOH (1b) or pyridine molecules (2). These hexanuclear U(iv) clusters are further linked into zig-zag 1-D chain structures via bridging HCOO - ligands. UV-vis-NIR spectra, together with bond valence calculations, indicate that all U atoms in three compounds exist as U(iv). Magnetic susceptibility data reveal that compound 2 exhibits paramagnetic characteristics.