Chromium-containing dendrimers

B. Chromium-, Cobalt-, and Iron Carbonyl-Containing Dendrimers.173... 

Cuadrado and co-workers have reported the synthesis of chromium-containing organosilicon dendrimers.334 These dendrimers, 282, have chromium tricarbonyl units incorporated pendent to the terminal aromatic rings.334 Synthesized via the reaction of the silane dendrimer precursor with chromium hexacarbonyl, complete complexation was not possible due to steric hindrance at higher generations. Electrochemical studies showed that the oxidation of the chromium atoms occurred reversibly in the absence of a nucleophilic species and that the chromium tricarbonyl units behaved as isolated redox centers. 

Dendrimers and star polymers containing redox active sites have been utilized in the design of new types of catalysts, sensors, bioelectronic devices, and molecular batteries. Highly branched polymers containing arenes coordinated to oiganometallic moieties have been prepared witii chromium tricarbonyl, cyclopenta-dienyliron, " and pentamethylcyclopentadienylrutheniiun moieties. Astruc and... 

Organosilicon dendrimers containing chromium tricarbonyl moieties pendent to peripheral aromatic rings (101) have been synthesized by Cuadrado. These organometallic dendrimers were isolated following reaction of a precursor silane dendrimer with chromiiun hexacarbonyl. It was not possible to effect complexation of every aromatic ring due to steric hindrance. Cyclic voltammetry of these materials indicated that oxidation of the chromium atoms occurred reversibly in the absence of nucleophilic species and that the chromium tricarbonyl imits behaved as isolated redox centers. 

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