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

Reaction of the dicarbon-containing complex [Ru-5(mu(5)-C-2)(mu-SMe)(2)(mu-PPh2)(2)(CO)(11)] 1 with monosubstituted alkynes HC=CR (R=Ph, Bu-t or SiMe3) yielded [Ru-5(mu(5)-CCCHCR)(mu-SMe)(2)(mu-PPh2)(2)(CO)(10)] (R=Ph, Bu-t or SiMe3) in which the Ru-5 pentagon in 1 is retained. Coupling of the C-2 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 [Ru-5(mu(5)-CCCHCR)(mu-SMe)(2)(mu-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 [Ru-5{mu(5)-CC[C(O)SMe]CHCR}(mu-SMe)(mu-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 Ru-5 core with an open-envelope conformation. Pyrolysis of [Ru-5(mu-CCCHCR)(mu-SMe)(2)(mu-PPh2)(2)(CO)(11)] afforded [Ru-5(mu(5)-CCCHCR)(mu-SMe)(2)(mu-PPh2)(2)(CO)(10)] and [Ru-5(mu(5)-CCCHCR)(mu(3)-SMe)(mu-SMe)(mu-PPh2)(2)(CO)(9)] (R=Ph or SiMe3), in which one SMe group becomes triply bridging. The complex [Ru-5{mu(5)-CC(CHCSiMe3)C(=CHSiMe3)CO}(mu-SMe)(2)(mu-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 [Ru-5{mu(5)-CC[C(O)SMe]CHCR}(mu-SMe)(mu-PPh2)(2)(CO)(10)], has also been isolated. The structures of five complexes were determined from single-crystal X-ray studies.