The kinetics of homolysis have been studied for (H2O)5Cr-CH2C6H5(2+) and derivatives with the following substituents : 4-CH3, 4-fluoro, 2,4-difluoro, 3,5-difluoro, 2-cyano, 3-cyano, and 4-cyano. The reactions have been studied in the general temperature range 20-35-degrees-C in 0.01-0.90 M HClO4 at ionic strength 1.00 M (NaClO4/HClO4). The reactions were done in the presence of several oxidizing scavengers, dioxygen, aqueous iron(III), (NH3)5CoCl2+, and (NH3)5CoBr2+. The homolysis rate is independent of the nature and concentration of the scavenger, and the rate constant (25-degrees-C) changes from 4 X 10(-3) to 0.23 X 10(-3) s-1 from the most reactive 4-methyl to the least reactive 3-cyano. This change is primarily due to a change in DELTAH* from 26 to 30 kcal mol-1, while DELTAS* is typically in the range 22-24 cal mol-1 K-1. The organic products, identified by H-1 NMR, vary considerably with the nature of the scavenger and the substituent on the benzyl ligand. With aqueous iron(III) in several systems, the products show competition between oxidation to form the alcohol and radical dimerization to give the bibenzyl derivative. From the dependence of the product distribution on the iron(III) concentration, the rate constant for oxidation of .CH2C6H5 by Fe(OH2)63+ is calculated to be 1.8 X 10(4) M-1 s-1. With (NH3)5CoBr2+, the more easily oxidized radicals give the alcohol, while others give a mixture of alcohol and bromide or exclusively bromide for the least oxidizable systems. However, (NH3)5CoCl2+ is different and gives only the bibenzyl derivative for all the systems.