Poly[bis(μ-2-amino-4-nitrobenzoato)di-μ-aqua-dirubidium]

Abstract

In the structure of the title salt, [Rb2(C7H5N2O4)2(H2O)2]n, the asymmetric unit comprises two independent and different seven-coordinate Rb+ cations, one forming an RbO7 polyhedron, the other a RbO6N polyhedron, each of which is considerably distorted. The RbO7 polyhedron comprises bridging O-atom donors from two water molecules, three carboxylate groups, and two nitro groups. The RbO6N polyhedron comprises the two bridging water molecules, one monodentate amine N-atom donor, one carboxyl O-atom donor and three O-atom donors from nitro groups (one from the chelate bridge). The extension of the dinuclear unit gives a three-dimensional polymeric structure which is stabilized by both intra- and intermolecular amine N—H...O and water O—H...O hydrogen bonds to carboxyl and water O-atom acceptors, as well as a number of inter-ring π–π interactions [minimum centroid–centroid separation = 3.364 (2) Å]. The title salt is isostructural with the analogous caesium salt.