Kinetics of reduction of a series of pentaaquo(pyridine)chromium(III) ions by 1-hydroxy-1-methylethyl radicals: evidence for electron transfer to pyridine

The title reaction was investigated for a series of (H/sub 2/O)/sub 5/Cr(NC/sub 5/H/sub 4/X)/sup 3 +/ ions. The rate constants are correlated by the Hammett equation. These data, in comparison to other cases in the literature, provide support for a mechanism in which a pyridyl radical, coordinated to Cr(III), is first formed. Subsequent intramolecular electron transfer to produce Cr/sup 2 +/ and pyH/sup +/ occurs more rapidly. Additional members of the series of free pyridinium ions, C/sub 5/H/sub 4/XNH/sup +/, were also investigated. 32 references, 2 figures, 4 tables.