We have previously reported the reactions of the activated cluster compound, [Ru 3 (CO) 10 (dppm)] (1), with ethyne-1,2-diyl compounds, [{Ru(CO) 2 (η-C 5 H 4 R)} 2 (μ-CC)], (2a, R=H; 2b, R=CH 3 ), which gave the new complexes [Ru 5 (μ 5 -CC)(η-C 5 H 4 R) 2 (dppm)(μ 2 -CO) 2 (CO) 7 ], (3a, R=H; 3b, R=CH 3 ). Our desire to extend the chemistry of these complexes required larger quantities of starting materials and in these syntheses we found that an additional complex, [Ru 5 (μ 4 -CC)(η-C 5 H 5 ) 2 (dppm)(μ-CO)(CO) 9 ] (4a), was formed. This apparently results from the reaction of 1 with 2, and is related to [Ru 5 (μ 5 -CC)(η-C 5 H 5 ) 2 (dppm)(μ 2 -CO) 2 (CO) 7 ] (3a) by the addition of a single carbonyl ligand. The reaction of complex 3b with CO was investigated and resulted in the isolation of [Ru 4 (μ 4 -CC)(η-C 5 H 4 Me) 2 (dppm)(CO) 9 ] (5b) and the isolation of complex 4b, which was identified by comparison of its spectroscopic properties with that of 4a, in addition the 13 CO labelling of complexes 3 resulted in the unequivocal assignment of the carbide resonances in their 13 C-NMR spectra