Tail-to-tail carbon-carbon bond coupling of acetylides on chalcogen-bridged Fe/W mixed-metal clusters

On thermolysis of a toluene solution containing [Fe3(CO)9(μ3-E)2] (E = S 1a, Se 16 or Te 1c) and [W(η5-C5Me5)2(CO)3(C≡CPh)]2 the new clusters [W2Fe3(η5-C5Me5)2(CO)6(μ3-E)2{μ4-CC(Ph)C(Ph)C}] (E = S 3, Se 4 or Te 5) were isolated. Compounds 3-5 were characterised by IR and 1H, 13C, 77Se and 125Te NMR spectroscopy. The crystal structure of 3 was elucidated by X-ray diffraction methods. It shows a novel tail-to-tail coupling of substituted acetylides on a sulfur-bridged mixed-metal Fe-W cluster