Reactions of the cluster complex [Ru5(μ5-C2)(μ-SMe)2(μ-PPh2)2(CO)11] with terminal alkynes HCCR (R = Ph, But or SiMe3)

Abstract

Reaction of the dicarbon-containing complex [Ru5(µ5-C2)(µ-SMe)2(µ-PPh2)2(CO)11] 1 with monosubstituted alkynes HCCR (R = Ph, But or SiMe3) yielded [Ru5(µ5-CCCHCR)(µ-SMe)2(µ-PPh2)2(CO)10] (R = Ph, But or SiMe3) in which the Ru5 pentagon in 1 is retained. Coupling of the C2 and alkyne moieties forms a CCCHCR ligand which in combination with one Ru atom forms a metallacycle. The unsubstituted terminal carbon has a strong carbidic interaction with four of the Ru atoms. Carbonylation of the R = Ph and SiMe3 complexes yields [Ru5(µ5-CCCHCR)(µ-SMe)2(µ-PPh2)2(CO)11] (R = Ph or SiMe3), in which one Ru atom has been extruded from the cluster, although retained by co-ordination to bridging PPh2, SMe and hydrocarbon ligands. A minor product in each case was identified as [Ru5{µ5-CC[C(O)SMe]CHCR}(µ-SMe)(µ-PPh2)2(CO)10 (R = Ph or SiMe3). Here, the organic ligand is formed by combination of the CCCHCR ligand with CO and one of the SMe groups and is attached to an Ru5 core with an open-envelope conformation. Pyrolysis of [Ru5(µ-CCCHCR)(µ-SMe)2(µ-PPh2)2(CO)11] afforded [Ru5(µ5-CCCHCR)(µ-SMe)2(µ-PPh2)2(CO)10] and [Ru5(µ5-CCCHCR)(µ3-SMe)(µ-SMe)(µ-PPh2)2(CO)9] (R = Ph or SiMe3), in which one SMe group becomes triply bridging. The complex [Ru5{µ5-CC(CHCSiMe3)C(=CHSiMe3)CO}(µ-SMe)2(µ-PPh2)2(CO)8], in which the organic ligand, formed by combination of CO, HC2SiMe3 and CCHSiMe3 molecules, is attached to the opposite side of the open-envelope cluster from that in [Ru5{µ5-CC[C(O)SMe]CHCR}(µ-SMe)(µ-PPh2)2(CO)10], has also been isolated. The structures of five complexes were determined from single-crystal X-ray studies.