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.