Syntheses,crystal structures and electron paramagnetic resonance studies of Co- and Mn-coordination polymers with the twisted ligand di(4-pyridyl)disulfide in double bridge fashion

Four coordination polymers, {Co₂(4-DPSS)₄(DMF)₄](ClO₄)₄}_n (1), {Mn₂(4-DPSS)₄(DMF)₄](ClO₄)₄}_n (2), {Co(4-DPSS)₂(H₂O)(NO₃)]NO₃·3H₂O}_n (3) and Co(4-DPSS)₂(NCS)₂]_n (4) have been synthesized to study the reactivity of cobalt(II) and manganese(II) salts (perchlorate, thiocyanate and nitrate) with the flexible ligand di(4-pyridyl)disulfide (4-DPSS). These compounds have repeated rhomboidal structures in which the di(4-pyridyl)disulfide ligands coordinate the metal centers in a double bridged fashion. Each double chain and the metallocycle cavities are chiral and contain either the M- or the P-enantiomeric forms of 4-DPSS and are independent on recrystallization solvents or the metallic precursors. The crystal packing of these coordination polymers reveals that, in all cases, weak interactions such as classical and non-classical hydrogen bonds, as well as S?S interactions, connect the polymeric chains to increase the dimensionality of the network. Low temperature electron paramagnetic resonance (EPR) measurements on powdered samples show that the transition-metal ions, Co (II) and Mn (II) ions, are in the high spin states S = 3/2 and 5/2, respectively, and adopt octahedral geometry in case of compounds 1, 2 and 3, and rhombic environment in case of 4.