Preparation and Properties of Cyclopentadienyl Ruthenocenium Complexes with 1,2-Disubstituted Benzene Ligands: Competition between Chelate Coordination and Sandwich Coordination

The reactions of [CpRu­(NCMe)₃]⁺ and 1,2-disubstituted benzene ligands (L) bearing donor substituents were examined to investigate the consequence of competing coordination modes. 1,2-C₆H₄(OMe)₂ and 1,2-C₆H₄(SMe)­(OMe) produce [CpRu­(η⁶-L)]⁺-type sandwich complexes with a η⁶ coordination mode, whereas 1,2-C₆H₄(SMe)₂ forms the chelate complex [CpRu­(κ²-L)­(NCMe)]⁺, due to the coordination ability of the donor atoms. 1,2-C₆H₄(NMe₂)₂ and 1,2-C₆H₄(SMe)­(NMe₂) produce the sandwich complexes or the chelate complexes ([CpRu­(κ²-L)­(NCMe)_<i>n</i>]⁺; <i>n</i> = 0 or 1) depending on the reaction conditions. The chelate complexes are the kinetic products and are thermally transformed into the sandwich complexes in solution. The hexafluorophosphate (PF₆) and bis­(trifluoromethylsulfonyl)­amide (Tf₂N) salts were isolated, and their thermal properties were investigated. The Tf₂N salts of the sandwich complexes are room-temperature ionic liquids. The molecular structures were determined crystallographically