Bridged species metal alkynyls

If the metals M and M are competitive in their affinities towards the alkynyl ligands RC=C, or if steric factors prevent the formation of type B tweezer complexes, then structural type C or D species are formed. In these molecules, the ligands RC C are more evenly shared, either with both metals, p-bridged by both alkynyl ligands (type C) or with each metal a-bonded by one alkynyl unit and rr-coordinated to the other (type D) [14]. 

They may be readily transformed to r] -aUcynyl and vinylidene complexes. The coupling of two ) -alkynyl ligands results in platinacyclopentadiene species." A platinum(II) disilyl( -alkyne) undergoes insertion (see Insertion) and reductive elimination (see Reductive Elimination) to disilacyclohexene (Scheme 31)." Metal-diaUcynyls can also play jr-donors to form the coordination complexes of various configurations, as shown in (10-13) and so on." Such a,tt-bridging modes may have interconversion. Multi- aUcynyl complexes can even constitute clusters or higher-order stractures. ... 

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