text: Synthetic routes to cumulenic carbido complexes can be efficient and lead to rapid, near quantitative product formation with simple purifications. This dimerization involves the formation of a vinylidene from an alkyne. Mechanistically, there are various proposed pathways, starting with oxidative addition of the alkyne to the metal core, followed by either intramolecular 1,2-H shifts or intermolecular 1,3-H shifts. For Ruthenium coordination complexes, bridging Ru-Cl bond lengths have been observed to lie in the range of 1.76-1.8 Å. Ru-C bonds can vary significantly as a result of trans effect phenomena which is caused by the respective ethylene and vinylidene ligands.