Stereochemical aspects of the conversion of cyclopentadienylruthenium alkoxycarbene to the corresponding acetylide complexes. Crystal structure of [(η-C5H5)Ru(Ph2PCHMeCHMePPh2)(CCPh)]
[(η-C5H5)RuPh2PCHRCHR′PPh2}(C(OCH3)CH2C6H5})]PF6 (where R, R′ = H or CH3) reacts with LiAlH4 in THF at −80° C to give the corresponding 2-phenylethyl complexes, which have an antiperiplanar conformation around the H2CCH2 bond in solution; the reaction takes place with retention of configuration at the ruthenium atom.