Synthesis and Reactivity of Cyclopentadienyl Ruthenium(II) Complexes with Tris(alkylthio)benzenes: Transformation between Dinuclear and Sandwich-Type Complexes

To explore the structural transformation of cyclopentadienyl ruthenium (CpRu) complexes in response to external stimuli, the reaction of [RuCp­(MeCN)3]­[X] (X = PF6, (FSO2)2N [= FSA]) and tris­(alkylthio)­benzenes (1,3,5-C6H3(SR)3; L1: R = Pr, L2: R = Me) was investigated, and the crystal structures and thermal properties of the products were examined. The reaction produced the sandwich complexes [RuCpLn]­[X] or dinuclear complexes [Ru2Cp2(μ-Ln)2(CH3CN)m]­[X]2 (X = PF6, FSA) depending on the reaction conditions. The sandwich complex [RuCpL1]­[FSA] was an ionic liquid. The solids of dinuclear complexes transformed into the thermodynamically stable sandwich complexes upon heating accompanied by acetonitrile loss. This change resulted in a transformation from crystal to ionic liquid for complexes with the FSA anion. UV irradiation of the sandwich complex [RuCpL1]­[PF6] in methanol produced the dinuclear complex [Ru2Cp2(μ-L1)2L12]­[PF6]2. The complex transformed into the sandwich complex upon heating.