Revisiting the reactivity of Ru3(CO)12 with PhC≡CPh (diphenylacetylene)-new findings of a thermic effect towards higher nuclearity

Abstract

In this paper, we report tri- and tetranuclear ruthenium carbonyl compounds containing PhC≡CPh ligand showing μ₃-η², μ₃-η⁴, μ₄-η²coordination modes. A one-pot reaction between [Ru₃(CO)₁₂] and PhC≡CPh in THF (tetrahydrofuran) at 66 °C has given the new trinuclear compound [Ru₃(CO)₆(μ-CO)₂(μ₃-η⁴-C₄Ph₄)] (<strong>2</strong>) in 30% yield together with the previously reported [Ru₃(CO)₈(μ₃-η²-C₂Ph₂)₂] (<strong>1</strong>) in 25% yield. Compound <strong>1</strong> converts to <strong>2</strong> under refluxing condition in THF. A similar reaction involving [Ru₃(CO)₁₂] with PhC≡CPh in refluxing benzene (80 ^°C) afforded previously reported <em>closo</em>-tetraruthenium compounds [Ru₄(CO)₁₂(μ₄-η²-C₂Ph₂)] (<strong>3</strong>) and [Ru₄(CO)₁₀(μ-CO)(μ₄-η²-C₂Ph₂)₂] (<strong>4</strong>) in 25 and 16% yields, respectively, along with <strong>2</strong> in 20% yield. Compounds <strong>1</strong>, <strong>2</strong> and <strong>4</strong> have been characterized by single-crystal X-ray diffraction analysis in addition to IR and ¹H NMR spectroscopic methods.