The first oxidation of a Cr24+ paddlewheel complex to an isostructural stable product

The first cation containing a Cr-2 core surrounded by a paddlewheel arrangement of four bridging ligands has been prepared and characterized. The bridging ligands are the guanidinate anions [(PhN)(2)CN(CH2)(4)](-). In the neutral Cr-2(4+) compound the average Cr-Cr distance is 1-904[1] Angstrom, and in the cation (which is accompanied by a PF6-anion) the Cr-Cr distance is 1.9249(9) Angstrom. The cation has one unpaired electron, but the EPR spectrum is devoid of hyperfine structure and has g approximate to 2.00. We proposed that the oxidation is essentially delocalized on the ligands.