Reactivity of electron-deficient triosmium quinoline cluster [Os3(CO)9(μ3-η2-C9H6N)(μ-H)] with alkynes

Reactions of the electron-deficient triosmium cluster [Os-3(CO)(9)(mu(3)-eta(2)-C9H6N)(mu-H)](1) with various alkynes are described. Cluster 1 readily reacts with the activated alkyne dimethyl acetylenedicarboxylate (dmad) upon mild heating (65-70 degrees C) to give the adduct [Os-3(CO)(9)(mu-C9H6N)(mu(3)-MeO2CCCHCO2Me)] (2). In contrast, a similar reaction of 1 with diphenylacetylene affords previously reported compounds [Os-3(CO)(10)(mu-eta(2)-C9H6N)(mu-H)] (3), [Os-3(CO)(9)(mu-C4Ph4)] (4) and [Os-3(CO)(8){mu(3)-C(C6H4)C3Ph3}(mu-H)] (5) while with 2-butyne gives only the known compound [Os-3(CO)(7)(mu-C4Me4)(mu(3)-C2Me2)] (6). The new cluster 2 has been characterized by a combination of spectroscopic data and single crystal X-ray diffraction analysis. (C) 2011 Elsevier B.V. All rights reserved.