Correlation of volumes and entropies of activation for oxidation of coordinated sulfur in bis-ethylenediaminecobalt(III) complexes by peroxodisulphate, hydrogen peroxide and periodate and for peroxodisulphate oxidation of diimine-cyanide–iron(II) complexes

Activation parameters ΔH‡, ΔS‡ and ΔV‡ and correlations between ΔS‡ and ΔV‡ are reported for peroxodisulphate oxidation of [Fe(CN)6]4−, [Fe(bipy)3]2+ (bipy = (2, 2′-bipyridyl), [Fe(phen)3]2+ (phen = 1,10-phenanthroline), cis-[Fe(bipy)2(CN)2], [Fe(bipy)(CN)4]2−, [Fe(phen)(CN)4]2−, [Co(en)2(glyS)]+ (glyS = mercaptoacetate, SCH2COO2−), [Co(en)2(cyS)]+ (cyS = cysteinate, SOCH2CH(COO)NH22−) and [Co(en)2(amS)]2+ (amS = ethanesulphenaminate, SCH2CH2NH2−) and for periodate and hydrogen peroxide oxidation of the three last-named complexes. Activation parameters are discussed in terms of electrostriction, solvation and ligand size contributions. Opposite trends for ΔS‡/ΔV‡ correlations were found for oxidations of FeII complexes in comparison with oxidations of coordinated sulphur in the CoIII complexes.