Attaching Metal-Capped sp Carbon Chains to Metal Clusters: Synthesis, Structure, and Reactivity of Rhenium/Triosmium Complexes of Formula [(η5-C5Me5)Re(NO)(PPh3)(CC)nOs3(CO)y(X)z]m+, Including Carbon Geometries More Distorted than Planar Tetracoordinate

A variety of fascinating C2, C3, C4, and C6 Re/Os3 complexes can be obtained, starting from thermal reactions of alkynyl complexes [(η5-C5Me5)Re(NO)(PPh3){(C≡C)nH}] and [Os3(CO)10(NCCH3)2], or the C3OMe complex [(η5-C5Me5)Re(NO)(PPh3)(C≡CC(OMe)=Os3(CO)11] alone. Two examples of such complexes are shown; the one on the right features a carbon with a geometry even more distorted than “planar tetracoordinate”.