ELECTRONIC INTERACTIONS IN MULTICLUSTER ARRAYS - AN ELECTROCHEMICAL APPROACH .3.

The electrochemical reduction of triangulo-dodecacarbonyl triruthenium , Ru-3(CO)(12), is re-investigated in strictly controlled experimental conditions and corresponds to an EC mechanism. Ru-3(CO)(12) undergoes a primary one-electron reduction process followed by a set of surface chemical reactions all producing electroactive species, giving rise t o apparent stoichiometry of the overall reduction process (n(app)) bet ween 1 and 2, depending on the concentration of depolarizer. Competiti on between solvent-assisted dissociation, disproportionation and redox condensation is assumed. The mu-bridged derivative [Ru-3(CO)(11)](2)( mu-dppa), (dppa=bis(diphenylphosphino)acetylene, Ph(2)PC=CPPh(2)) is r educed in one two-electron step followed by chemical decomposition rea ction generating the 'dangling' complexes Ru-3(CO)(11)(eta(1)-dppa) an d [Ru-3(CO)(11)](2-). The electrochemical behaviour of [Ru-3(CO)(11)]( 2)(mu-dppa) indicates no electrochemically detectable interaction betw een the two Ru-3(CO)(11) redox units in the dimer, but a deeper evalua tion of the electronic communication through the dppa bridge is hinder ed by the following fast chemical complications.