Paramagnetic Organometallic Molecules. 4. Electrochemical Investigation of the Iron Group Carbonyls and Their Phosphine-Substituted Derivatives

Alan M. Bond, Peter A. Dawson, Barrie M. Peake, Brian H. Robinson, Jim Simpson

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The redox behavior of the iron carbonyl species Fe3(CO)12-nLn (n = 0-3) and Fe(CO)5-nLn (n = 0-2) (L = PPh3, P(OMe)3, P(OPh)3) has been studied in acetone and dichloromethane using the techniques of dc polarography at mercury electrodes and dc cyclic voltammetry at platinum electrodes. A chemically reversible one-electron reduction step was observed for the triiron species within the temperature range 203-293 K. The ET 1/2 values for the reduction became increasingly negative with increasing phosphine substitution which correlates well with the charge density on the iron atoms in the parent complexes. The carbonyls Ru3(CO)12 and Os3(CO)12 undergo an irreversible reduction within the temperature range of this investigation leading to rapid decomposition of the carbonyl moieties. Further reduction to the dianions Fe3(CO)12-nLn2- occurred for the iron species and caused irreversible disintegration of the cluster unit. A one-electron oxidation step was observed for Fe3(CO)9[P(OMe)3]3. The mononuclear iron derivatives gave well-defined one-electron oxidation and two-electron reduction waves at mercury electrodes. The oxidation step was found to be chemically reversible. No evidence was found for the formation of the radical anion Fe(CO)5- under the experimental conditions employed.

Original languageEnglish
Pages (from-to)2199-2206
Number of pages8
JournalInorganic Chemistry
Issue number9
Publication statusPublished - 1 Sep 1977
Externally publishedYes

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