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.

Reactions of the Tetrahedral Clusters [MCo3(CO)12]-(M = Ru, Fe) with Functional Mono- and Diynes

“…The carbonyl C(6)O(6) is the only one to be semibridging, namely, between Ru and Co(2): Co(2)−C(6) = 1.815(7) Å, Co(2)−C(6)−O(6) = 154.5(6)°, Ru···C(6) = 2.386(7) Å. The alkyne ligand is coordinated in a classical μ 3 -η 2 fashion over the metal triangle, as observed in [RuCo 2 (CO) 9 (μ 3 -η 2 -PhC 2 Ph] 18 and [Ru 2 Ir(CO) 9 (μ 3 -η 2 - PhC 2 Ph] - . The C(10)−C(11) bond is almost parallel to the Ru−Co(1) edge [C(10)−Co(1)−Ru−C(11) = 0.1(3)°].…”

“…Interestingly, in the related [FeCo 2 (CO) 9 (μ 3 -η 2 -EtC 2 Et)] cluster, the alkyne is also bonded in a μ 3 -η 2 mode but in contrast to 6 it is parallel to the Co−Co vector . The alkyne carbon−carbon bond length of 1.372(8) Å compares with that in [RuCo 2 (CO) 9 (μ 3 -η 2 -PhC 2 Ph)] (1.370(3) Å) 18 and in [Ru 2 Ir(CO) 9 (μ 3 -η 2 -PhC 2 Ph)] - (1.363(11) Å) . Cluster 6 has the expected electron count of 48e for trinuclear clusters which obey the EAN rule.…”

Routes to Ruthenium−Cobalt Clusters and Dicobalt Complexes with New Alkoxysilyl- or Sulfur-Functionalized Alkynes. X-ray Structures of [NEt4][RuCo3(CO)10{μ4-η2-HC2(CH2)2OC(O)NH(CH2)3Si(OEt)3}] and [Co2(CO)6{μ2-η2-HC2CH2NHC(O)NH(CH2)3Si(OEt)3}]

“…Indeed, reactions of alkynes with carbonylmetal clusters afford a considerable diversity of structural types and bond activation processes, and the stability of the products is largely due to the formation of covalent metal−carbon bonds, usually involving a triangular or rectangular face of the metal polyhedron. If one considers the large family of tetrahedral metal clusters, the products generally obtained are of the butterfly type, with the organic fragment interacting with the metals in a μ 4 -η 2 -bonding mode. , Alternatively, these clusters may be viewed as having a closo structure in which the two carbon atoms originating from the alkyne are part of the skeleton. The stability of the metal−carbon σ bonds explains that subsequent reactions may occur by breaking of metal−metal bond(s) and partial cluster fragmentation rather than by splitting of the organic moiety …”