Reactions of co-ordinated nucleophiles. Preparation, characterization, and crystal structure of penta-ammine(phenylthiocarbamato-S)cobalt-(III) perchlorate monohydrate

Abstract

The title complex [Co(NH₃)₅(SCONHPh)][ClO₄]₂ has been prepared by the addition of [Co(NH₃)₅(OH₂)]-[ ClO₄]₃ to phenyl isothiocyanate in dimethylformamide. A mechanism for formation of the complex is proposed whereby an O-bonded complex is initially formed and then isomerizes rapidly to the stable S-bonded species. The stable complex has been characterized by spectroscopic methods and by X-ray crystallography. Crystals are orthorhombic, space group Pnam, with eight molecules of the hydrate, [Co(NH₃)₅(SCONHC₆H₅)][ClO₄]2·H₂O, in a unit cell of dimensions a = 9.573(5), b= 11.300(5), and c= 37.40(2)Å. The structure was refined by full-matrix least-squares calculations to a final R value of 0.096 for 660 ‘ observed ’ reflections. The Co atom is octahedrally co-ordinated [Co–N 1.98–2.02(3), Co–S 2.264(9)Å]. An extensive network of hydrogen bonds links the cations, anions, and water molecules.