Preparation and thermolysis of complexes derived from some trinuclear ruthenium clusters and 1,4-diphenylbuta-1,3-diyne

Article abstract of DOI:10.1016/S0022-328X(96)06492-3

Reactions between Ru₃(μ-dppm)(CO)₁₀ and PhC≡CC≡CPh in thf, in the presence of Me₃NO, afford the complexes Ru₃(μ₃-PhC₂C≡CPh)(μ-dppm)(μ-CO)(CO)₇ (1) and Ru₃(μ-dppm){μ-C₄Ph₂(C≡CPh)₂}(CO)₆ (2). Complex 1 was also obtained from Ru₃(μ₃-PhC₂C≡CPh)(μ-CO)(CO)₉ (3) and dppm in thf on heating. Two of the complexes formed by thermolysis of 1 in xylene at 130 °C were identified crystallographically as Ru₃{μ₃-CPhCHCC(C₆H₄-2)}(μ-dppm)(CO)₈ (4) and Ru₃{μ₃-C₄H₂Ph₂}(μ-CO)(CO)₅(dppm) (5). In 4, fragmentation of the cluster and metallation of one of the diyne phenyl groups took place; the dppm ligand bridges two non-bonded Ru atoms. In 5, partial hydrogenation of the diyne has occurred to give a 2η¹:η⁴:η⁴-butadiendiyl ligand, the dppm ligand adopting a chelating mode on one of the two Ru atoms which is η⁴ attached to the hydrocarbon. In comparison, thermolysis of 3 gave Ru₄(μ₄-PhC₂C≡CPh)(CO)_n (n = 12 (6) and 14 (7)). The former has a distorted C₂Ru₄ octahedral core, while in the latter the Ru₃ cluster has fragmented to give a ruthenacyclopentadiene derivative in which the central C-C bond bridges an Ru₂(CO)₈ group.