Synthesis, electronic structure and redox properties of the diruthenium sandwich complexes [Cp*Ru(μ-CH)RuCp*] (x = 0, 1+; Cp* = CMe; CH = naphthalene).

The dinuclear ruthenium complex [CpRu(μ-C10H8)RuCp] (1; Cp* = η5-C5Me5) was prepared by reduction of the cationic precursor [CpRu(η6-C10H8)]PF6 with KC8. Diamagnetic 1 has a symmetric molecular structure with an anti-facial configuration of the CpRu moieties coordinating to naphthalene. Density Functional Theory (DFT) studies showed an electronic structure similar to that of the analogous diiron complex [CpFe(μ-C10H8)FeCp]. Cyclic voltammetry and UV-vis spectroelectrochemistry showed that 1 can be reversibly oxidized to 1+ and 12+. Chemical oxidation with [Cp2Fe]BArF4 afforded the paramagnetic compound [1]BArF4, which was investigated by EPR, single-crystal X-ray diffractometry and DFT calculations. Reaction of 1 with Brookhart's acid gave the hydride complex [3]BArF4, which was characterized spectroscopically and crystallographically. Cyclic voltammetry showed that [3]+ is converted back to 1 upon reduction and oxidation.