Anion binding through second sphere coordination: Synthesis, characterization and X-ray structures of cationic carbonato bis(1,10-phenanthroline)cobalt(III) complex with sulphur oxoanions

In an effort to utilize the cationic cobalt(III) complex, [carbonato bis(1,10-phenanthroline)cobalt(III)](+) as an binding agent (anion receptor) for the sulphur oxcianions (S2O32-, S4O62-, S2O82-), three complex salts of composition [Co(phen)(2)CO3] [Co(phen)(2)(S2O3)]center dot 5-5H(2)O (1), [Co(phen)(2)CO3](2)S4O6 center dot 7H(2)O (2) and [Co(phen)(2)CO3](2) S2O8 center dot 4H(2)O (3) were synthesized and characterized by UV/Visible, IR, NMR and conductance measurements. The molecular structure of complex salts 1-3 were determined by single crystal Xray crystallography which revealed the presence of discrete ions and lattice water molecules in the solid state. A strong network of hydrogen bond interactions through the weak second sphere interactions (CH center dot center dot center dot O) and strong interactions of type O-H center dot center dot center dot O (water) besides the electrostatic interactions play a very important role in stabilizing the crystal lattice. The solubility product measurements, X-ray structure analyses and formation of these salts suggest that cation, [Co(phen)(2)CO3](+) present in [Co(phen)(2)-CO3]Cl center dot 5H(2)O may be used as an anion receptor for the sulphur oxoanions S2O32-, S4O62- and S2O82- ions. (C) 2009 Elsevier B.V. All rights reserved.