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

Abstract

[Ru₃(CO)₁₂] reacts with 2,5-bis(2-thienyl)-1-phenyl-phosphole (btpp) in refluxing CH₂Cl₂ to afford mono-, di- and trisubstituted derivatives: [Ru₃(CO)₁₁(btpp)] (1), [Ru₃(CO)₁₀(btpp)₂] (2) and [Ru₃(CO)₉(btpp)₃] (3), as well as the unique ruthenacyclopentadiene compound [Ru₂(CO)₄(μ-CO)(btpp)(μ-η¹:η¹:η⁴-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)(η⁴-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 π-conjugated structures that might be interesting in the development of new organometallic materials. The reaction of [Os₃(CO)₁₀(CH₃CN)₂] with btpp in refluxing CH₂Cl₂ affords mono- and disubstituted clusters: [Os₃(CO)₁₁(btpp)] (6) and [Os₃(CO)₁₀(btpp)₂] (7). The trisubstituted complex [Os₃(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 [Os₃(CO)₉(btpp)₃] (8). A comparative analysis of the UV-vis spectra of [Ru₃(CO)₉(btpp)₃] (3) and [Os₃(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.