Oligoynediyl bridges

Just as vinylidene-type resonance forms constitute one extreme description for the oxidised forms of alkynyl complexes (Scheme 6.4), cumulenic structures may result from the oxidation of oligoynediyl-bridged dimetal complexes (Schemes 6.5 to 6.8). Interesting examples come from the work of Sato, who... 

Heterodimetallic complexes with fully conjugated oligoynediyl or diethynyl arene bridges constitute another interesting family of compounds where an assignment of individual redox sites may not be trivial. In these systems, strong... 

As we have noted in a previous section of this chapter, cumulenic resonance forms present one extreme description for dimetal complexes linked by all carbon bridges. They are frequently encountered in some oxidation state (mostly the dioxidised one) and also contribute to intermediate ones between the purely cumulenic and oligoynediyl or the cumulenic- and the alkynyl-bridged dicarbyne forms (see Schemes 6.6-6.8). Purely cumulenic wires are encountered in ot,a)-di- or -tetraferrocenyl substituted cumulenes, but no evidence other than a splitting of the ferrocenyl-based redox waves has been presented to support the presence of electronic interactions between the fer-rocenyl end groups across the cumulenic ligands. Based on the results of ex-... 

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