Chemical oxidations of piano-stool chromium/cobalt carbonyl complexes Cr(CO)(3)(eta(6),eta(5)-C6H3C5H4)Co(CO)(2) (1) and Cr(CO)(3)(eta(6),eta(6)-C6H5C6H5) Cr(CO)(3) (2) were investigated. Upon one-electron oxidation, 1 was transformed to a heterometalloradical species, 1(center dot+). However, either one- or two-electron oxidation of 2 afforded a decomposition product, 3. Dipping 3 into pentane led to the formation of 4 via a crystal-to-crystyal transformation with the removal of solvent molecules. Complexes 1(center dot+) and 4 were fully characterized by various spectroscopic techniques and single-crystal X-ray analysis. Cation 1(center dot+) features a weak Cr-Co bond with a Wiberg bond order of 0.278. A near-infrared absorption band around 1031 urn was observed for 1(center dot+), which is far red-shifted in comparison to previously reported dinuclear metalloradical species. Complex 4 contains a chromium(II) with a distorted pyramidal geometry and displays single-molecule magnetic properties.