Synthesis and Reactivity of New Ruthenium Alkyls and Hydrides. Protonation of Cp*Ru(Me2PCH2PMe2)Me and X-ray Crystal Structure of Cp*2Ru2(μ-Ph2PCH2PPh2)(AlH5)

Abstract

Treatment of the pentamethylcyclopentadienylruthenium chloride tetramer [Cp*RuCl]4 with bis(dimethylphosphino)methane (dmpm) in tetrahydrofuran affords three ruthenium(II) phosphine complexes, Cp*Ru(dmpm)Cl, [Cp*Ru(dmpm)(η1-dmpm)]Cl, and Cp*2Ru2(μ-dmpm)2Cl2. Similar treatment of [Cp*RuCl]4 with bis(diphenylphosphino)methane (dppm) in tetrahydrofuran or diethyl ether affords the dinuclear species Cp*2Ru2(μ-dppm)(μ-Cl)2; in acetonitrile, this same reaction yields the mononuclear product Cp*Ru(dppm)Cl in high yield. The mononuclear complexes Cp*Ru(P-P)Cl (where P-P is dmpm or dppm) can be alkylated with dimethylmagnesium in diethyl ether to give the methyl complexes Cp*Ru(dmpm)Me and Cp*Ru(dppm)Me. Protonation of these Cp*Ru(P-P)Me complexes with trifluoroacetic acid results in the rapid reductive elimination of methane and formation of the trifluoroacetato complexes Cp*Ru(P-P)(η1-O2CCF3); no ruthenium(IV) hydridomethyl intermediates could be detected. Treatment of Cp*2Ru2(dppm)2Cl2 with LiAlH4 in diethyl et...