Ruthenium, alkyne-bridged clusters reactions

There are syntheses where the new metallic species enhances a different type of reactivity. This has been observed in the reactions between alkyne-substituted ruthenium clusters and compounds of mercury (145, 146). In most of the characterized products a mercury atom or an HgX2 (X = halogen) fragment serves as a bridge between two ruthenium cluster frameworks which retain the coordinated alkyne. 

The use of Me3NO to induce substitution of dppm (bis(diphenylphosphino)-methane) for CO molecules on dinuclear iron complexes led to insertion of CO into C-C bonds of alkyne-derived metallacycles. Similar behavior was observed when [PPNJCl salts were used to favor the formation of alkyne-substituted triruthenium dppm-containing clusters.I This behavior should be compared with the insertion of CO into allenylidene and phosphido-bridging ligands occurring when dppm coordinates to binuclear ruthenium complexes as shown in Fig. 3. This reaction is a nucleophilic attack of the coordinated allenylidene and phosphido groups on a coordinated CO (see Section 2.8.2.2). 

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