Preparation and Reactivity of Stannyl Complexes of Ruthenium(II) Stabilized by an Indenyl Ligand

Trichlorostannyl complexes Ru­(SnCl3)­(η5-C9H7)­(PPh3)­L (1; L = P­(OMe)3, P­(OEt)3) were prepared by allowing chloro compounds RuCl­(η5-C9H7)­(PPh3)­L to react with SnCl2·2H2O in ethanol. Treatment of compounds 1 with NaBH4 in ethanol yielded the tin trihydride derivatives Ru­(SnH3)­(η5-C9H7)­(PPh3)­L (2). The reaction of trichlorostannyl complexes 1 with MgBrMe in diethyl ether afforded the chlorodimethylstannyl derivatives Ru­(SnClMe2)­(η5-C9H7)­(PPh3)­L (3), whereas reaction with Li+CCPh in THF yielded the trialkynylstannyl compounds Ru­[Sn­(CCPh)3]­(η5-C9H7)­(PPh3)­L (4). Treatment of the trihydridostannyl complexes 2 with the alkyl propiolate HCCCOOR led to the trivinylstannyl derivatives Ru­[Sn­{C­(COOR)CH2}3]­(η5-C9H7)­(PPh3)­L (5, 6; R = Me, Et). However, the reaction of [Ru]–SnH3 (2) with the propargylic alcohol HCCCPh2OH yielded the alkene H2CC­(H)­CPh2OH and the hydride RuH­(η5-C9H7)­(PPh3)­L (7). Treatment of tin trihydride complexes 2 with H2O led to the trihydroxostannyl derivatives Ru­[Sn­(OH)3]­(η5-C9H7)­(PPh3)­L (8). Protonation of [Ru]–SnH3 (2) with triflic acid (HOTf) produced the very unstable dihydridostannyl compound Ru­[SnH2(OTf)]­(η5-C9H7)­(PPh3)­L (9). Stabilization of SnH2 species was achieved by protonation with HOTf at −30 °C of the cyclopentadienyl compound Ru­(SnH3)­(η5-C5H5)­(PPh3)­[P­(OMe)3], which yielded the complex Ru­[SnH2(OTf)]­(η5-C5H5)­(PPh3)­[P­(OMe)3] (10a). The complexes were characterized by spectroscopy (IR and 1H, 31P, 13C, and 119Sn NMR data) and by X-ray crystal structure determinations of Ru­[Sn­(CCPh)3]­(η5-C9H7)­(PPh3)­[P­(OEt)3] (4b) and Ru­[Sn­(OH)3]­(η5-C9H7)­(PPh3)­[P­(OEt)3] (8b).