Diverse dimensionalities and structures in copper coordination polymers incorporating substituted aliphatic dicarboxylate ligands and 4,4′-bipyridine

Hydrothermal synthesis has afforded a series of divalent copper coordination polymers with substituted glutarate ligands and the rigid rod tether 4,4'-bipyridine (bpy): {[Cu(Hdmg)(2)(bpy)]center dot H2O}(n) (1, dmg = 3,3-dimethylglutarate), {[Cu-2(dmg)(bpy)(2)](ClO4)](n) (2), [Cu-2(emg)(2)(bpy)](n) (3, emg = 3-ethyl, 3-methylglutarate) and [Cu-2(cda)(2)(bpy)](n) (4, cda = 1,1-cyclopentanediacetate). All materials were characterized by single-crystal X-ray diffraction. Compound 1 manifests mu(2)-oxygen bridged [Cu-2(Hdmg)(4)] X-patterns connected into a ribbon motif by bpy linkers. On the other hand, 2 possesses mixed-valence [(CuCuCuII-CuI)-Cu-I-Cu-II] tetrameric clusters bridged by dmg ligands and pillared into an 8-connected body-centered cubic (bcu) cationic lattice by bpy linkers. Compounds 3 and 4 are structurally very similar, displaying chain motifs with {Cu-2(CO2)(4)} paddlewheels connected by dicarboxylates, in turn conjoined into (4,4)-grid coordination polymer layers by bpy tethers. Variable temperature magnetic data indicate the presence of very strong antiferromagnetic coupling within the {Cu-2(CO2)(4)} paddlewheels in the latter two complexes, with g = 2.30(2) and J = -352(3) cm (1) for 3 and g = 2.35(2) and J = -352(5) cm (1) for 4. Significant structural contrasts are evident when compared to previously reported divalent copper/4,4'-bipyridine coordination polymers with unsubstituted or 2-methyl substituted glutarate ligands. (C) 2009 Elsevier B. V. All rights reserved.