Polymeric Structures in The Metal Complexes of 5-Sulfosalicylic Acid: The Rubidium(I), Caesium(I) and Lead(II) Analogues

The complexes of 3-carboxy-4-hydroxybenzenesulfonic acid (5-sulfosalicylic acid, H3SSSA) with rubidium(I), caesium(I) and lead(II) have been synthesized and characterized using single crystal X-ray methods at 130 K. The rubidium(I) complex 1, [Rb3(H2SSA)(HSSA)(H2O)4]n, is an unstable hydrate variant of a previously described complex [Rb(H2SSA)(H2O]n, and comprises three independent and different seven-coordinate metal polyhedra interlinked through oxygen donors of the sulfonate, carboxylate and phenolate groups of the 5-sulfosalicylate ligands (one of which is dianionic, the other monoanionic), and one bridging water, giving a three-dimensional hydrogen-bonded framework polymer structure. The anhydrous caesium(I) complex 2 [Cs(H2SSA)]n, which has breen previously described in a room-temperature determination, has a three-dimensional framework polymer structure based on an irregular Cs-O9 repeating unit. Complex 3 with lead(II), [Pb(H2SSA)2(H2O)]n, forms helical step-polymer ribbon sub-structures having an irregular Pb-O7 coordination centre comprising a single monodentate water and six sulfonate-O donors bridging three separate metals. The carboxylic acid and phenol substituent groups of the 5-sulfosalicylate ligand link the ribbons peripherally through hydrogen bonds, giving a three-dimensional layered polymer structure.