Variation in the Coordination Mode of Arenedisulfonates: Syntheses and Structural Characterization of Mononuclear and Dinuclear Cadmium(II) Arenedisulfonate Complexes with Two- to Zero-Dimensional Architectures

Seven cadmium(II) arenedisulfonate compounds, namely [Cd(2,2‘-bpy)2(H2O)(peds)]·4H2O (1), [Cd2(2,2‘-bpy)4(H2O)2(1,5nds)](1,5nds)·4H2O (2), [Cd(cyclam)(1,5nds)]2 (3), {[Cd(inia)2(H2O)2(2,6nds)]·4H2O}n (4), {[Cd(inia)2(H2O)2(bpds)]·4H2O}n (5), {[Cd2(inia)4(H2O)3(peds)2]·2H2O}n (6), and [Cd(1,5nds)(H2O)2]n (7), where 2,2‘-bpy = 2,2‘-bipyridyl,
cyclam = 1,4,8,11-tetraazacyclotetradecane, inia = isonicotinamide, nds = naphthalenedisulfonate, bpds = 4,4‘-biphenyldisulfonate, and peds = 4,4‘-phenyletherdisulfonate, have been obtained from aqueous solution by using
similar procedures and structurally characterized by X-ray single-crystal diffraction, IR spectroscopy, and thermal
gravimetric analysis. In 1, the peds anion coordinates as a monodentate ligand, leading to a mononuclear unit. In
2 and 3, the 1,5nds anions coordinate as μ2-bridging ligands in different modes, producing charged or neutral
dinuclear clusters. In 4 and 5, 2,6nds and bpds behave as μ2-spacers, resulting in 1-dimensional polymers. While
in 6, the peds acts both as terminal and bridging ligands with the SO3- groups being either monodentate or
μ2-bridging, creating a knotted 1-dimensional polymer with dinuclear clusters as the repeating units. In 7, 1,5nds
acts as a bridging ligand with each SO3- coordinated as a μ2-bridging group to adjacent Cd(II) centers, leading to
a 2-dimensional polymer. Together with the reported {[Cu(en)2(1,5nds)]·2H2O}n (8), all of the six possible coordination
modes adopted by organodisulfonate anions, on the assumption that each SO3- group could be monodentate or
μ2-bridging, are realized by introducing nitrogen-containing organic ligands as auxiliaries.