Reactions of [Os3(CO)10(MeCN)2] with ethynyl thiophenes: The formation of linked clusters

The reaction of 2 equiv. of [Os3(CO)10(MeCN)2] with R–CC–L–CC–R (R = H, L = (C4H2S); R = SiMe3, L = (C4H2S–C4H2S), (C4H2S–C4H2S–C4H2S), (C4H2S)–(C14H8)–(C4H2S)) affords the series of linked clusters [{Os3(CO)10}(HCC(C4H2S)CCH){Os3(CO)10}] (1), [{Os3(CO)10}(Me3SiCC(C4H2S–C4H2S)CCSiMe3){Os3(CO)10}] (2), [{Os3(CO)10}(Me3SiCC(C4H2S–C4H2S–C4H2S)CCSiMe3){Os3(CO)10}] (4) and [{Os3(CO)10}(Me3SiCC(C4H2S)–(C14H8)–(C4H2S)CCSiMe3){Os3(CO)10}] (6) as the major products. The complexes have been characterised by a range of spectroscopic methods and, in the case of 1 and 2 by single crystal X-ray crystallography. The alkyne groups cap the osmium triangles in the expected μ3-η2-||-bonding mode and each triangle is coordinated by nine terminal and one μ2-carbonyl group. Solution UV–Vis spectra of the complexes were similar to those observed for the free ligands consistent with there being little delocalisation between the cluster units and the thiophene groups.