Oxidation of arsenous acid and a revisit to those of P(I) and N(III) by ethylenebisbiguanidinesilver(III) ion in acid medium

The oxidation of arsenous acid by ethylenebisbiguanidinesilver(III) complex ion in perchloric acid medium is considered to involve the following mecha nism. As(OH)(3) + [Ag(enbbg)](3+)reversible arrow (Ko) [As(OH)(3)Ag(enbbg)](3+) ( i) [As(OH)(3)Ag(enbbg)](3+)--> Ag-ko(H2O)(+) + enbbg + H3AsO4 + 2H(+) (ii) [As(OH)(3)Ag(enbbg)](3+) + H+--> (kh(H2O))Ag+ + enbbg + H3AsO4 + 3H(+) (iii ) Reactions (i)-(iii) lead to the rate law (iv) with the assumption that 1 mu ch greater than K[As(OH)(3)] and k = k(o)K(o), and k(H) = khKKo and k(2) = k(obs)/[As(OH)(3)] k(2) = (k + k(H)[H+]) (iv) It is further suggested that a lone pair of electron is needed for the addu ct fonnation with d(8)Ag(III) planar complex before the electron transfer. In oxygenated compounds the lone pair is available with the oxygen atom or could be acquired through deprotonation of O-H bond. The acquired lone pair is considered more reactive and the same is discussed in the context of th e previously studied oxidations of nitrous and hypophosphorous acids. A new mechanism for the oxidation of hypophosphorous acid is also suggested.