From copper(II) carboxylate to copper(II) 4-pyridylsulfonate coordination polymers as a consequence of the copper(II)-assisted oxidative cleavage of the 4,4′-dipyridyldisulfide ligand

Five coordination polymers 1 {[Cu-4(HCO2)(6)(OH)(2)(4dpdS)(2)]center dot 2CH(2)Cl(2)}(n), 2 {[Cu-4(CH3CO2)(6)(OH)(2)(4dpds)(2)]}(n), 3 {[Cu(4dpds)(2)(H2O)(2)](4pySO(3))(2)center dot 2H(2)O}(n), 4 {[Cu(4pySO(3))(2)(4dpds)(2)]center dot 2H(2)O}(n) and 5 {[Cu(4pySO(3))(2)(dmso)(2)]center dot 2H(2)O)(n) (where 4dpds = 4,4'-dipyridyldisulfide, 4pySO(3) = 4-pyridyisulfonate) have been obtained during a study into the reactivity of basic copper(II) salts (formate and acetate) with 4,4'-dipyridyldisuffide (4dpds). The coordination polymers 1 and 2 consist of a repeated rhomboid structure in which analogous Cu-4(RCO2)(6)(OH)(2) cores are joined by two 4,4'-dipyridyldisuffide bridging ligands to generate two different chain topologies: planar ribbon in 1 and ruffled ribbon in 2. 4-Pyridylsulfonate ions appear as ligands or counterions in the coordination polymers 3, 4 and 5 due to oxidative cleavage of the 4,4'-dipyridyldisuffide under mild conditions. The coordination polymer 3 has been isolated repeatedly in several direct reactions of the copper(II) carboxylates with 4,4'-dipyridyldisulfide. However, the coordination polymers 4 and 5 have been obtained from I and 2, respectively, by recrystallization from DMF and DMSO. In compound 4, as in 3, the 4,4'-dipyridyidisulfide has only been partially oxidized to 4-pyridylsulfonate and a proportion of these units remain in the structure as disulfide. However, in 5 the oxidation is complete. The structural analysis of these coordination polymers reveals that, in all cases, weak interactions such as classical and non-classical hydrogen bonds, as well as CH center dot center dot center dot pi, S center dot center dot center dot pi and S center dot center dot center dot O interactions, join the polymeric chains to generate three-dimensional networks.