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(CH(2))(4)](-). In the neutral Cr(2)(4+) compound the average Cr-Cr distance is 1.904[1] A, and in the cation (which is accompanied by a PF(6)(-) anion) the Cr-Cr distance is 1.9249(9) A. The cation has one unpaired electron, but the EPR spectrum is devoid of hyperfine structure and has g approximately 2.00. We proposed that the oxidation is essentially delocalized on the ligands.