Butenynyl and Vinylidene Complexes of Ruthenium

Reaction of ruthenium bis-acetylide complexes with 2,6-lutidinium tetrafluoroborate gave butenynyl complexes cis-[Ru(η3-RCCCC(H)R)(PMe3)4]BF4 in moderate to good yields. The structure of cis-[Ru(η3-tBuCCCC(H)tBu)(PMe3)4]BF4 was determined crystallographically. Attempts to prepare cis-[Ru(η3-MeCCCC(H)Me)(PMe3)4]BF4 resulted in the formation of two isomers, which differ in the stereochemistry about the double bond. The reaction of two bis-acetylide complexes with methyl triflate afforded butenynyl-type complexes cis-[Ru(η3-RCCCC(Me)R)(PMe3)4]+ (R = Me, Ph). The mixed acetylide−vinylidene complex trans-[Ru(CCSiMe3)(CCH2)(PMe3)4]PF6 was prepared by the reaction of trans-Ru(CCSiMe3)2(PMe3)4 with ammonium hexafluorophosphate. In addition, the crystal structure of trans-[Ru(CCH)(CCH2)(PMe3)4]BF4 is reported.