An electron transfer series of octahedral chromium complexes containing a redox non-innocent α-diimine ligand

An electron-transfer series of octahedral alpha-diimine complexes [(L-H(Cy))(3)Cr](n+)(BARF)(n) (n = 2, 1, 0) has been synthesized and crystallographically characterized. Cyclic voltammetry indicated additional formation of [(L-H(Cy))(3)Cr](3+). The molecular structures suggested that all redox processes were ligand-based. Magnetic moments were consistent with spin ground states of S = 0 for [(L3Cr)-L-H-Cr-Cy](0), S = 1/2 for [(L3Cr)-L-H-Cr-Cy](+1), and S = 1 for [(L3Cr)-L-H-Cr-Cy](+2). The experimental data is consistent with chromium maintaining the +III oxidation state throughout, while being coordinated by varying numbers of neutral diimines (L-H(Cy)) and diimine radical anions (L-H(Cy center dot-)).