Kinetics of Oxidation of Azide by [Ethylenebis(biguanide)]silver( III ) in Aqueous Acidic Media

In aqueous acidic media sodium azide and the orange‐yellow title complex react quantitatively generating N 2 gas along with a colourless solution of Ag + ion and the ligand, ethylenebis(biguanide). The parent complex, [Ag(H 2 L)] 3+ , and one of its conjugate bases, [Ag(HL)] 2+ , participate in the reaction with N 3 − as the kinetically reactive reductant. Ag + has no catalytic effect. At 25.0 °C, I = 1.0 M (NaNO 3 ), rate constants for the reactions [Ag(H 2 L)] 3+ + N 3 − and that for [Ag(HL)] 2+ + N 3 − are (12.3±0.5) and (3.8±0.6) M −1 ·s −1 , respectively. The high rate constants along with the very low equilibrium constant (10 −15 M −1 ) calculated for the first reaction strongly suggest inner‐sphere redox mechanism. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)