Alkylidyne ligands, metal centers,

The chemistry of CR fragments ligating metal centers has been a topic of considerable interest since the discovery of the first alkylidyne-metal complexes in E.O. Fischer s Laboratory in 1973 (1). These ligands have been implicated in Fischer-Tropsch reactions (2) and in alkyne metathesis (5). Moreover, the isolation of stable compounds containing carbon-metal triple bonds completed the matrix of bond types represented here ... 

The generation and interconversion of hydrocarbon fragments on metal surfaces is an important aspect of transition metal catalysis. In an effort to model and understand these transformations, much attention has been focused on the synthesis and reactivity of organic species coordinated at polynuclear transition metal centers. Organodiruthenium complexes have provided a particularly rich area of study. The availability of a variety of organometallic derivatives of the bis(T) -cyclopentadienyl)diruthenium carbonyl system has allowed extensive examination of the reactivity of bridging alkylidene, alkylidyne, and ethenylidene ligands. 

The protonation of vinylidene ligands bound to electron-rich metal centers is well-known to give the corresponding alkylidyne complexes. The first kinetic study of such a process has been reported for the reaction shown in Eq. (26). The kinetic data were rationalized in terms of the overall mechanism shown in Scheme 10. For example, in the presence of excess NHEt3BPh4, reaction (26) obeys the rate law (27), which is a limiting form of the general rate law for Scheme 10. Initial... 

---