Trinuclear mixed-valence complexes with the linear [Rh3]4+ core

The complexes [Rh3(µ3-L)2(CO)4(PPh3)2][BF4][1+; L = 1,8-naphthyridin-2-onate (napyo) or 5,7-dimethyl-1,8-naphthyridin-2-onate (dmnapyo)] and [Rh3(µ3-L)2(CO)2(µ4-cod)2][BF4](2+; cod = cyclo-octa-1,5-diene) undergo two reversible one-electron oxidations at a platinum bead electrode in CH2Cl2. Chemical oxidation of (1+) or (2+) with [N(C6H4Br-p)3][BF4] in CH2Cl2, or electrolytic oxidation at a platinum electrode, gave the mixed-valence dications [Rh3(µ3-L)2(CO)4(PPh3)2]2+(12+; L = napyo or dmnapyo) and [Rh3(µ3-L)2(CO)2(η4-cod)2]2+(22+; L = napyo or dmnapyo), isolated as the violet bis(tetrafluoroborate) salts, and characterised by i.r., visible, and e.s.r. spectroscopy and by cyclic voltammetry.