Reaction of carbonyl trinuclear clusters with 2,5-bis(2-thienyl)-1-phenyl-phosphole as a ligand: a new pathway to ruthenacyclopentadiene and cyclopentadienone ruthenium complexes

[Ru-3(CO)(12)] reacts with 2,5-bis(2-thienyl)-1-phenyl-phosphole (btpp) in refluxing CH2Cl2 to afford mono-, di- and trisubstituted derivatives: [Ru-3(CO)(11)(btpp)] (1), [Ru-3(CO)(10)(btpp)(2)] (2) and [Ru-3(CO)(9)(btpp)(3)] (3), as well as the unique ruthenacyclopentadiene compound [Ru-2(CO)(4)(-CO)(btpp)(-(1):(1):(4)-C16H14S2)] (4), whose structure was confirmed by single-crystal X-ray crystallography. The photolysis of 3 in CH2Cl2 leads to the novel complex [Ru(CO)(2)(btpp)((4)-COC16H14S2)] (5), such that its single-crystal structure reveals the fragmentation of the triruthenium cluster, leading to a cyclopentadienone ruthenium complex. The synthesis of both ruthenacyclopentadiene (4) and cyclopentadienone (5) ruthenium complexes opens access to inaccessible ligand systems with -conjugated structures that might be interesting in the development of new organometallic materials. The reaction of [Os-3(CO)(10)(CH3CN)(2)] with btpp in refluxing CH2Cl2 affords mono- and disubstituted clusters: [Os-3(CO)(11)(btpp)] (6) and [Os-3(CO)(10)(btpp)(2)] (7). The trisubstituted complex [Os-3(CO)(9)(btpp)(3)] (8) is formed by reaction of compound 7 with equimolar amounts of trimethylamine oxide and btpp. In contrast to 3, no fragmentation product was detected from the triosmium carbonyl cluster [Os-3(CO)(9)(btpp)(3)] (8). A comparative analysis of the UV-vis spectra of [Ru-3(CO)(9)(btpp)(3)] (3) and [Os-3(CO)(9)(btpp)(3)] (8) suggests that their different photochemical reactivities might not only be affected by the energetics of their electronic transitions, but also by a combination of subsequent metal-ligand and metal-metal intramolecular interactions.