Approaches toward (η2-HX) (X = H, SiR (R = Me3 or Me2Ph), CH3) sigma-complexes of ruthenium

•Two new ruthenium(II) complexes with Tpms ligand have been synthesized.•Attempts to prepare sigma complexes of H2, HSiMe3, and CH4 were made.•Succeeded in obtaining sigma complexes of H2 and silane but not methane.•Crystal structures of some of the complexes have been determined.

Two new Ru(II)-complexes [RuH(Tpms)(PPh3)2] 1 (Tpms = (C3H3N2)3CSO3, tris-(pyrazolyl)methane sulfonate) and [Ru(OTf)(Tpms)(PPh3)2] 2 (OTf = CF3SO3) have been synthesized and characterized wherein Ru–H and Ru–OTf are the key reactive centers. Reaction of 1 with HOTf results in the [Ru(η2-H2)(Tpms)(PPh3)2][OTf] complex 3, whereas reaction of 1 with Me3SiOTf affords the dihydrogen complex 3 and complex 1 through an unobserved σ–silane intermediate. In addition, an attempt to characterize the sigma methane complex via reaction of complex 1 with CH3OTf yields complex 2 and free methane. On the other hand, reaction of [Ru(OTf)(Tpms)(PPh3)2] 2 with H2 and PhMe2SiH at low temperature resulted in σ–H2, 3 and a probable σ–silane complexes, respectively. However, no σ–methane complex was observed for the reaction of complex 2 with methane even at low temperature.

Graphical abstractApproaches toward the realization of η2-HX (X = H, SiR (R = Me3 or Me2PH), CH3) sigma complexes of ruthenium are described. Whereas complexes bearing η2-H2 and η2-SiH moieties were obtained, attempt to prepare η2-CH4 complex resulted in free methane evolution.Figure optionsDownload full-size imageDownload as PowerPoint slide