Poly[diaquadi-[mu]6-oxalato-[mu]5-oxalato-chromium(III)rubidium(I)]: a new supramolecular isomer

• Published in: Acta crystallographica. Section C, Crystal structure communications Crystal structure communications, 2011-04, Vol.67 (4), p.m85
• Main Authors: Kherfi, Hamza, Hamadène, Malika, Guehria-Laïdoudi, Achoura, Dahaoui, Slimane, Lecomte, Claude
• Format: Article
• Language: English
• Subjects: Atoms & subatomic particles; Chemical compounds; Crystal structure; Crystallography; Hydrogen bonds
• ISSN: 0108-2701; 1600-5759
• DOI: 10.1107/S0108270111005646

The title compound, [CrRb(C2O4)2(H2O)2]n, obtained under hydrothermal conditions and investigated structurally at 100K, is a three-dimensional supramolecular isomer of the layered structure compound studied at room temperature. This novel polymer is built up from crosslinked heterobimetallic units. The linkage of alternating edge- and vertex-shared RbO7(H2O)2 and CrO4(H2O)2 polyhedra running along three different directions gives a dense packing. The two independent ligands display two η4-chelation modes and two conventional carboxylate bridges. However, the pentadentate ligand connects the CrIII and RbI ions through one O-atom bridge, while the hexadentate ligand exhibits an additional η3-chelation and two O-atom bridges. Each coordinated water molecule forms an O-atom bridge between the two metals. Moreover, in the absence of protonated ligands, these water molecules act as donors through their four H atoms in strong-to-weak hydrogen bonds. This results in zigzag chains of alternating oxalate and aqua ligands parallel to the twofold screw axis. The six double oxalates known to date containing an alkali and CrIII all present layered two-dimensional structures. In the series, this supramolecular isomer is the first three-dimensional framework. [PUBLICATION ABSTRACT]