Effect of Cl— and SO42— on the Paramagnetic Resonance Linewidth of Mn2+ in Aqueous Solution and the Rates of Formation of the Complex Ions

The linewidth of one of the hyperfine components in solutions of Mn(ClO4)2 containing added NaCl and Na2SO4 was studied from 20°—200°C at 9000 Mc/sec. The chloride ion contributes little broadening at 0.1M below 80°C but considerable broadening is obtained above this temperature. The sulfate contributes broadening at all temperatures. The rates of formation of ``inner-sphere'' and ``outer-sphere'' complexes are discussed together with their rates of relaxation. At the lower temperatures the ``outer-sphere'' complexes primarily contribute to the broadening while at the higher temperatures the ``inner-sphere'' complexes also contribute. From the broadening above 80°C the rate of formation of the ``inner-sphere'' complexes are evaluated.