Reactivity of metal acetylides with chalcogen-bridged metal carbonyl cluster in presence of free alkyne molecule: synthesis and characterisation of [(η5-C5Me5)MFe3(μ3-S){(μ3-C(H)C(R)S}(CO)6(μ3-CCPh)] (R=Ph, n-Bu and M=W, Mo) and [(η5-C5Me5)MFe3(μ3-S){(μ3

Photolysis of benzene solution of [Fe3(CO)9(μ3-S)2] (1), [(η5-C5Me5)M(CO)3(C≡CPh)] (2a: M=W, 2b: M=Mo) and HC≡CR (3a: R=Ph, 3b: R=n-Bu, 3c: R={(η5-C5H5)(η5-C5H4)Fe}(Fc) yields two types of clusters: [(η5-C5Me5)MFe3(μ3-S){(μ3-C(H)C(R)S}(CO)6(μ3-CCPh)] (4: M=W, R=Ph; 5: M=Mo, R=Ph: 6: M=W, R=n -Bu; 7: M=Mo, R=n-Bu) and [(η5-C5Me5)MFe3(μ3-S){(μ3-C(Fc)C(H)S}(CO)7(μ3-CCPh)] (8: M=W; 9: M=Mo) featuring new C–S bond formation. The formation of 8 and 9 involve an unusual head to tail flip of the coordinated acetylide group. All compounds have been characterised by IR and 1H- and 13C-NMR spectroscopy. The structures of 5 and 8 have been established by X-ray crystallography.