Cp*(PiPr₃)RuOTf: A Reagent for Access to Ruthenium Silylene Complexes

The ruthenium triflate complex Cp*(PiPr 3 )RuOTf ( 1 ) was generated from the reaction of Cp*(PiPr 3 )RuCl with Me 3 SiOTf in dibutyl ether. Complex 1 reacted with primary and secondary silanes to produce a family of Ru(IV) silyl dihydride complexes of the type Cp*(PiPr 3 )Ru(H) 2 (SiRR′OTf) ( 3 – 12 ). Structural analyses of complexes 8 (R = R′ = Ph) and 12 (R = R′ = fluorenyl) revealed the presence of a tetrahedral silicon center and a four-legged piano stool geometry about ruthenium. Anion abstraction from Cp*(PiPr 3 )Ru(H) 2 (SiHROTf) by [Et 3 Si·toluene][B(C 6 F 5 ) 4 ] afforded hydrogen-substituted cationic ruthenium silylene complexes [Cp*(PiPr 3 )Ru(H) 2 (═SiHR)][B(C 6 F 5 ) 4 ] (R = Mes ( 13 ), R = Si(SiMe 3 ) ( 14 )) that display a significant Ru–H···Si interaction, as indicated by relatively large 2 J SiH coupling constants ( 2 J SiH = 58.2 Hz ( 13 ), 2 J SiH = 37.1 Hz ( 14 )). The syntheses of secondary silylene complexes [Cp*(PiPr 3 )Ru(H) 2 (═SiRR′)][B(C 6 F 5 ) 4 ] (R = R′ = Ph ( 15 ); R = Ph, R′ = Me ( 16 ), R = R′ = fluorenyl ( 17 )) were also achieved by anion abstraction with [Et 3 Si·toluene][B(C 6 F 5 ) 4 ]. Complexes 15 – 17 do not display strong Ru–H···Si secondary interactions, as indicated by very small 2 J SiH coupling constant values.