Clusters carbonyl substitution reactions

Substitution reactions on metal-carbonyl dimers (see Dinuclear Organometallic Cluster Complexes) and clusters see Polynuclear Organometallic Cluster Complexes) occur by replacement of a CO with an entering ligand ... 

The catalytic substitution reactions of metal carbonyl clusters, including [M3(CO)i2] (M = Fe, Ru, or Os), [Ru4H4(CO)i2], [Rh6(CO)i6], and [Co3(CO)9(/it-CCl)], with isocyanides or Group V-donor ligands may be induced by either electrochemical or chemical (benzophenone ketyl) reduction. The most favorable conditions for efficient substitution include (1) the formation of a radical anion with a significant lifetime and (2) the use of a ligand which is not reduced by [Ph2CO], and which is less of a tt acid than CO (166). 

In CH2CI2 solution this cluster compound undergoes the expected (on the basis of the cited oxidation behavior of free bis(diphenylphosphino)ferrocene) irreversible one-electron oxidation of the ferrocene fragment (Ep0/-l- = 4-0.88 V), followed by the (once again expected on the basis of the multiple carbonyl substitution) one-electron oxidation of the C03 assembly ( p -I-/2-I- = -f 1.31 V). The reduction process ( p 0/— = —1.16 V) typical of the CC03 assembly is also complicated by following chemical reactions [131]. 

Clusters containing dienes or bridging acetylenes are prepared by carbonyl substitution on preformed clusters. However, particularly with clusters of first- and second-row metals, this reaction leads to the formation of larger clusters with the ligand acting as a template. Yields are low and numerous products are observed. 

Reactions of ruthenium and osmium cluster carbonyls with heteroatom-substituted and functionalized alkynes (metallocycles) 00IZV1. 

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