آلية إنتقال الأكترون لأكسدة الكروميوم الثلاثى باستخدام الجاوسن والأسبرتات الثنائى

The oxidation of the ternary complex, [Cr(III)(Gu)(Asp)(H2O)2]2+ (Gu = guanosine and Asp = DL-aspartic acid) by periodate in aqueous solution to chromium(VI) has been studied spectrophotometrically over the 25–45o with respect to both [IO4–] and [Cr(III)], and increases with pH over the 2.38–3.68 range. The experimental rate law is consistent with the derived mechanism and the reaction follows the rate law: d[Cr(III)]/dt = (k1K5 + k2K6K1/[H+])[IO4–][Cr(III)]T/{1 + K1/[H+] + (K5 + K1K6/[H+])[IO4–]}, where K1, K5 and K6 are the deprotonation of [Cr(III)(Gu)(Asp)(H2O)2]2+ and pre-equilibrium formation constants for [Cr(III)(Gu)(Asp)(H2O)(OIO3)]+ and [Cr(III)(Gu)(Asp)(OH)OIO3] precursor complexes, respectively. The reaction may follow a 2-step inner-sphere electron transfer mechanism via coordination of IO4– to chromium(III). Thermodynamic activation parameters have been calculated.