In dimethylformamide containing tetramethylammonium tetrafluoroborate and deliberately added water, stoichiometric quantities of 1-bromooctane and electrogenerated cobalt(I) salen react to give octylcobalt(III) salen. When a solution of octylcobalt (III) salen is irradiated with ultraviolet-visible light, the cobalt-carbon bond is broken to form an octyl radical and cobalt (II) salen within a solvent cage. Introduction of dioxygen causes an insertion reaction that leads to an octylperoxocobalt (III) salen intermediate, which subsequently decomposes to produce 1-octanal in up to 47% yield. Under similar experimental conditions, a two-to-one molar ratio of electrogenerated cobalt (I) salen and alpha,alpha'-dibromo-m-xylene gives rise to mu-(1,3-xylenyl)-bis[(salen)cobalt(III)] which can photodecompose, followed by insertion of dioxygen, to afford mu-(1,3-xylenyl)-bis[dioxo(salen)cobalt(III)]. Then the latter intermediate undergoes decomposition to form m-phthaldialdehyde in up to 61% yield. In contrast, the ortho and para isomers of alpha,alpha'-dibromoxylene react with electrogenerated cobalt (I) salen, eventually to give a dialdehyde in small quantities (3 - 10%). (c) 2005 The Electrochemical Society.