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

Abstract

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 Ru3μ3-CPhCHCC(C6H4-2)(μ-dppm)(CO)8 (4) and Ru3μ3-C4H2Ph2(μCO)(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.