Reactions of a Trinuclear Ruthenium Complex Derived from 3-(2-Pyridyl)indene with Diphenylacetylene and Phenylacetylene: Insertion of Alkynes into the Ru−C bond

Abstract

Thermal treatment of the trinuclear ruthenium complex {μ2-η5:η1-(C5H4N)(C9H5)}Ru3(CO)9 (1) with 1 equiv of diphenylacetylene gave the trinuclear complex {μ3-η1:η2:η5-(C5H4N)(C9H5)(PhC═CPh)}Ru3(CO)7 (2) via the insertion of an alkyne into the Ru−C(η1) bond of 1. Complex 2 could be transformed into the dinuclear and trinuclear complexes {μ2-η1:η5-(C5H4N)(C9H5)(PhC═CPh)}Ru2(CO)2(μ2-η2:η4-CPh═CPhCPh═CPh) (3), {μ3-η2:η3:η5-(C5H4N)(C9H5)(CPhCPh═CPhCPh)}Ru3(CO)6 (4), and {μ2-η1:η5-(C5H4N)(C9H5)(PhC═CPh)}Ru3(CO)4(μ3-η2-PhC═CPh)2 (5) in the presence of excess diphenylacetylene. Similarly, reaction of 1 with 1 equiv of phenylacetylene gave the alkyne-inserted product {μ3-η1:η2:η5-(C5H4N)(C9H5)(HC═CPh)}Ru3(CO)7 (6), which could also react with excess phenylacetylene to give the complexes {μ3-η2:η4:η5-(C5H4N)(C9H5)(C═CPhCH═CPh)}(μ2-H)Ru3(CO)6 (7) and {μ2-η2:η4-(C5H4N)(C9H6)(C═CPhCH═CPh)}Ru2(CO)4(μ2-CO) (8). Complex 7 could be transformed slowly into 8 in refluxing toluene. The reactions of 3-(2-pyridyl)indene with internal alkynes catalyzed by Ru3(CO)12 and 1 were also tested, obtaining several C−H/alkyne coupling products, while the reaction with phenylacetylene did not work under the same conditions. The molecular structures of 2−8 were determined by X-ray diffraction.