Electron-Transfer Reactions of Multidentate Ligand Cobalt(III) Complexes. II. The Effect of Nonbridging Ligands

Abstract
The specific rates for the Fe2+ reductions of cis-Co(en)2ACl2+ (A=methyl-, ethyl-, propyl-, butyl-, ethanol-, and propanolamine), Co(dien)(en)Cl2+ and Co(tetren)Cl2+ have been determined. The observed rates are relatively insensitive to the cis-ligand of the A. The rate constant for the cis-Co(en)2ACl2+ decreases with an increase in the size of the A ligand. In such cases as that of the aminoalcohol ligand, the rate is greater than that of the corresponding alkylamine ligand complex. The effect of chelation by nonbridging ligands has been discussed by comparing the relative effectiveness for Fe2+ reductions of CoN5Cl2+ (N5=(NH3)5, (en)2NH3, (dien)(en), and tetren) with that for Cr2+ reductions of some Co(III) complexes.

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