Reaction of Polymer Amminecobalt(III) Complexes with Chromium(II)

Chromium(II) reduction of malonatotetraamminecobalt(III) and tris(malonato)cobaltate(III)

“…The product, believed to be ds-Co(NH3)4(H20)(C3H304)2+, gave Xmax 508 nm (< 65 Af-1 cm-1) and Xmax 357 nm (« 50 Af-1 cm-1) and is remarkably similar to other cis complexes containing aquo and carboxylato ligands, e.g., Co(NH3)4(H20)(02CCH3)2+: Xmax 510 nm (e 67 Af-1 cm-1), Xmax 355 nm (e 50 M-1 cm-1). 7 Further spectrophotometric changes at 516 nm were observed over a period of many days, t\/2 = 10 days, when the spectrum approached more closely that of ' -0)( 3)4( 2 )23+. The rate constant <10-6 sec-1 indicated in these experiments for the second stage of the aquation is in keeping with known behavior of, e.g., Co(NH3)5(02CCH3)2+, which aqua tes extremely slowly, rate constant 1.6 X 10~8 sec-1 at 25°.…”

Electron-transfer reaction of macromolecular cobalt(III) complex with [Ru(NH3)6]2+. Effect of microenvironment occupied by polymer backbone

“…Despite the considerable experimental and theoretical studies of electron-transfer reactions of common metal complexes, there are few data on those of synthetic macromolecule-metal complexes.1'7 Aquochromium(II) reduction of polypeptide-amminecobalt(III) complex, obtained by reaction of aquopentaamminecobalt(III) perchlorate with poly(glutamic acid), has been reported. 1,2 The results of detailed investigation suggested that there may be two parallel reactions: the faster and slower processes ascribed to the reduction of acidotetraamminecobalt(III) and (carboxylato)aquotetraamminecobalt(III), respectively. 2 The results of kinetic studies on the redox reactions of polycation-bound Co(III) complexes and anionic iron(II) complexes indicated that the most important factor governing the rate is Coulombic interaction.3"7…”

“…1,2 The results of detailed investigation suggested that there may be two parallel reactions: the faster and slower processes ascribed to the reduction of acidotetraamminecobalt(III) and (carboxylato)aquotetraamminecobalt(III), respectively. 2 The results of kinetic studies on the redox reactions of polycation-bound Co(III) complexes and anionic iron(II) complexes indicated that the most important factor governing the rate is Coulombic interaction.3"7…”