Cobalt complexes chlorites

JCS 124, 11, 767 (1923) CA 18, 362 (1924) iPrepn and some props of several cobalt ammines, such as hexammine-cobalt (ni) chlorite [Co(NH,),] (CIO ), HjO and chloropentamminecobalt (III) chlorite [Co(NH,)5 Cl] (ClOj)a are given. These complexes are less stable then the corresponding chlorates and perchlorates (See items Co20 and Co24 in table D) 11)W. Friederich P.Vervoorst, SS21, 4S>-52,... 

The adsorption of transition metal complexes by minerals is often followed by reactions which change the coordination environment around the metal ion. Thus in the adsorption of hexaamminechromium(III) and tris(ethylenediamine) chromium(III) by chlorite, illite and kaolinite, XPS showed that hydrolysis reactions occurred, leading to the formation of aqua complexes (67). In a similar manner, dehydration of hexaaraminecobalt(III) and chloropentaamminecobalt(III) adsorbed on montmorillonite led to the formation of cobalt(II) hydroxide and ammonium ions (68), the reaction being conveniently followed by the IR absorbance of the ammonium ions. Demetallation of complexes can also occur, as in the case of dehydration of tin tetra(4-pyridyl) porphyrin adsorbed on Na hectorite (69). The reaction, which was observed using UV-visible and luminescence spectroscopy, was reversible indicating that the Sn(IV) cation and porphyrin anion remained close to one another after destruction of the complex. 

Aquation of the chlorito complex [Co(NH3)5(C102)] forms part of the overall substitution and redox reactivity pattern established for this complex. Indeed the mechanism of aquation involves an internal redox process. Rate constants and activation parameters for aquation of this chlorito complex in acidic aqueous solution are k29 = 8.0 x 10 s A// = 105 kJ mol and AS = + 13 J mol Although this complex could hardly be described as robust, the chlorite anion is considerably less fragile when coordinated to cobalt(III) than when bonded to Cobalt(III)-amine complexes of organic carbox-... 

Azo pigments group Metal complex sub-group Chlorite group Hexacyanoferrate group Metal pigments Nickel phosphate hydrate Smalt Smaltite Wad Barium titanate yellow. Cobalt green-. Nickel brown-. Nickel rutile yellow... 

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