80719-06-8Relevant academic research and scientific papers
Anodic reaction of CO(η5-C5H5)(CO) (PPh3): An oxidatively induced ligand exchange involving a 17 e -/18 e- redox pair
Nafady, Ayman,Geiger, William E.
, p. 4276 - 4281 (2010/12/20)
Unlike a number of other monocarbonyl-substituted complexes CoCp(CO)L (Cp = (η5-C5H5)), chemical oxidation of the L = triphenylphosphine derivative CoCp(CO)(PPh3), 1, is known to give, in the absence of added PPh3, the disubstituted phosphine complex [CoCp(PPh3)2]+ rather than the simple 17-electron radical cation 1+. Electrochemistry of 1 in CH 2Cl2/[NBu4][B(C6F5) 4] (E1/2(1/1+) = -0.38 V vs ferrocene) shows that the favored anodic products depend on the concentration of 1. At low concentrations (e.g., 10-4 M) and on the cyclic voltammetry time scale, the radical cation 1+ dominates, but at higher concentrations and longer reaction times, a quantitative mixture of CoCp(CO)2 and [CoCp(PPh3)2]+ is produced in an overall half-electron process. On the basis of cyclic voltammetry, chronoamperometry, bulk electrolysis, and IR spectroelectrochemistry, a radical-substrate mechanism is proposed involving the reaction of 1+ with 1 to give transient [Co2Cp2(CO) 2(PPh3)2]+. This putative dimer radical cation intermediate may be viewed as an odd-electron analogue of the intermediates that have previously been invoked by Kochi, Atwood, and others to explain ligand-transfer reactions between cation/anion pairs of organometallic complexes.
