Kinetics and mechanism of dissociation of some chelate complexes of cobalt(III) and chromium(III)

Kinetic and Mechanistic Studies on the Oxidation of Nitrogen(III) (HNO2/$\rm{{{NO}}_2^ - }$) by the Tris(biguanide)manganese(IV) Ion in Aqueous Acidic Media

“…At lower pH, protonation on the free imino 2 ) or amino group of the metal-bound ligand exerts a pull on the bonded electrons, and the effect is relayed through the molecule that renders the MnÀN bonds weaker and facilitates the electron acceptance of Mn IV . A similar mechanism for acid-catalyzed aquation of the hexacoordinated complexes of Cr III and Co III with biguanide and substituted biguanide ligands was proposed earlier [37], and the rate was found to decrease with decreasing basicity of the biguanide ligands. Above pH 3.0, the protonation was, as found, not much effective compared to that at low pH ( Table 2), though detectably finite, as evidenced from rate lowering (albeit small) in D 2 O at pH > 3.0.…”