Cationic cobaltammines as anion receptors: Synthesis, characterization and X-ray structure of bis-(hexaamminecobalt(III)) tris-(hydrogenarsenate) tetrahydrate

The orange coloured single crystals of bis-(hexaamminecobalt(Ill)) tris-(hydrogenarsenate) tetrahydrate, [Co(NH3)(6)](2)(HASO(4))(3)center dot 4H(2)O, have been prepared by reacting aqueous solutions of hexaamminecobalt(III) chloride with disodium hydrogenarsenate in 1: 1 molar ratio. The title complex salt was characterized by elemental analyses and spectroscopic studies (IR, UV/visible). X-ray crystal structure determination of the title complex salt revealed the presence of discrete ions, i.e., cation [Co(NH3)(6)](3+) and anion HASO(4)(2-) and four water molecules in the solid state. A strong network of hydrogen bond interactions (N-H center dot center dot center dot O (hydrogenarsenate), N-H center dot center dot center dot O (water), O-H center dot center dot center dot O (hydrogenarsenate)) stabilize the crystal lattice. The formation of definite salt and measurement of solubility products suggest that [Co(NH3)(6)](3+) may be used as an anion receptor for hydrogenarsenate anion. (c) 2006 Elsevier B.V. All rights reserved.