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

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