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.

Approaches 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 as PowerPoint slide