Tri- and Tetranuclear Mixed-Metal Clusters Containing Alkyne Ligands: Synthesis and Structure of [Ru3Ir(CO)11(RCCR′)], [Ru2Ir(CO)9(RCCR′)], and [HRu2Ir(CO)9(RCCR′)

Abstract

The tetrahedral cluster anion [Ru3Ir(CO)13]– (1) reacts with internal alkynes RC≡CR′ to afford the alkyne derivatives [Ru3Ir(CO)11(RCCR′)]–(2: R = R′ = Ph; 3: R = R′ = Et; 4: R = Ph; R′ = Me; 5: R = R′ = Me) which have a butterfly arrangement of the Ru3Ir skeleton in which the alkyne is coordinated in a μ4-η2 fashion. Under CO pressure they undergo fragmentation to give the trinuclear cluster anions [Ru2Ir(CO)9(RCCR′)]– (6: R = R′ = Ph; 7: R = R′ = Et; 8: R = Ph; R′ = Me; 9: R = R′ = Me), in which the alkyne ligand is coordinated in a μ3-η2 parallel fashion. Protonation of these trinuclear anions leads to the formation of the corresponding neutral hydrido clusters [HRu2Ir(CO)9(RC≡CR′)] (10: R = R′ = Ph; 11: R = R′ = Et; 12: R = Ph; R′ = Me; 13: R = R′ = Me). The protonation of the butterfly anions 2 and 3, however, gives rise to the formation of the neutral tetrahedral clusters [HRu3Ir(CO)11(RCCR′)] (14: R = R′ = Ph and 15: R = R′ = Et), respectively. The analogous clusters [HRu3Ir(CO)11(PhCCCH3)] (16) and [HRu3Ir(CO)11(CH3CCCH3)] (17) are only accessible from the reaction of the neutral cluster [HRu3Ir(CO)13] with the corresponding alkynes. The complexes 2, 4, 5, 6, 10, 12 and 15 are characterised by X-ray structure analysis.