Reaction of Acetylenes with Edge Double-Bridged Triruthenium Complexes

Abstract

The complex Ru 3 {u-H,u-O=C(NMe 2)}(C0) 10, in, [1], reacts with aryl acetylenes at 25 °C (Ar = Ph, p-CH 3 C 6 H 4, or p-(CH 3 O)C 6 H 4) giving only dinuclear products Ru 2 {μ-O=CNMe2,μ-σ,n-C(Ar)=CH(Ar)} (CO) 6, [5a,b,c] in 50-80% yield, and Ru 2 {μ-n 2,n 4 -C(Ar)=C(Ar)-C(Ar)=C(Ar)}(C0) 6, [6a,b,c], in 20-25% yield. Crystal and molecular structures have been determined for [5b] and for Ru 2 {μ-O=CNMe 2, μ-σ,n-C(Ph)=CH(Ph)} (CO)5 (PPh3), [9], both existing exclusively as the vic isomers in the solid state. At -50 °C, 1 H or 13 C NMR spectra of these complexes indicate two isomers in solution (vic and gem) which are rapidly interconverting. Through complexes of Ph 2 13 C 2, it is possible to assign the predominant species in solution as the gem isomer in both cases. □Reaction of phenylacetylene with [1] gives an unstable product which can be isolated only as the PPh3 substituted complex RU 2 {μ-O=CNMe 2,μ-σ,n-C(Ph)CH 2 } (CO) 5 (PPh 3), [10]. Only the Markcwnikoff adduct is seen, and no NMR signal averaging occurs between the vic and gem isomers at 23 °C. Crystal and molecular structure reveal exclusively the gem isomer in the solid state. □Reaction of [1] with hexafluorobut-2-yne gives the dinuclear adduct, Ru 2 {μ-H,μ-O=CNMe 2,μ-C(CF 3)=C(CF3)) (CO) 6, [11], in 56% yield, with no evidence of a μ-σ,n-isomer. □Complex [5b] reacts with propyne at 23 °C to give the all-cis-l-butadienyl complex Ru 2 {μ-O= CNMe2,μ-σ,n-CMe=C(H)R}(CO) 6, R= cis-C(p-tol)=CH(p-tol), [12], 48% yield; crystal and molecular structure show the gem isomer in the solid state. © 1988 IUPAC