Reactions of [RuCI2(COD)], (COD=cyclo-octa-l,5-diene) with the chiral bidentate phosphine ligands 2,2'bis(diphenylphosphin0)-1,1 '-binaphthyl, BINAP, and 2,2'-bis(di-p-tolylphosphino)-l,l '-binaphthyl, p-tolyl-BINAP, give new chi ral ruthenium (11) com plexes, Ru2CJ4( BI NAP)2( N Et3) and Ru~Cl4(p-tolyI-BI NAP)2( NEt3) respectively, which serve as excellent catalysts for asymmetric hydrogenation of alkenes and some cyclic anhydrides.

Five-membered metallacyclic alkynes that have no substituents adjacent to the triple bond have been synthesized, isolated, and structurally characterized. Zirconocene dichlorides, Cp'2ZrCl2 (Cp' = C5H5, C5H4-t-Bu), reacted with 1,4-dichlorobut-2-yne in the presence of magnesium to give 1-zirconacyclopent-3-yne compounds (5 (a) Cp' = C5H5, (b) Cp' = C5H4-t-Bu) that have a -CH2CCCH2- moiety in good yields. They are stable enough to be isolated in a pure form, despite the absence of substituents. 5a reacted with an equimolar amount of Cp2Zr(but-1-ene)(PMe3) to produce a bimetallic complex in which the zirconacyclopentyne coordinates to the other zirconocene moiety as an alkyne.

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