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

Abstract

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)n]+; n = 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.